Climate-Driven Water Scarcity and Its Public Health Implications: A Multi-Regional Assessment Across Vulnerable Socio-Ecological Systems

Abstract

Climate change is reshaping global hydrological cycles, intensifying scarcity and heightening health risks in vulnerable regions. This study examines the health impacts of climate-driven water scarcity across the Middle East, South Asia, and Sub-Saharan Africa using data on water availability, climate variability, and health outcomes. The study uses a multi-regional mixed methods approach that brings together climate, hydrology, governance, and health data to explore how climate-driven water scarcity affects public health in South Asia, Sub-Saharan Africa, and the MENA region. It combines quantitative climate and health indicators with qualitative evaluations of water system vulnerability to compare exposure pathways and health outcomes across regions. Findings show that rising temperatures, altered rainfall, declining groundwater, and recurrent droughts undermine water security, leading to increased disease burdens through four pathways: (1) waterborne illnesses from unsafe or insufficient supplies; (2) reduced hygiene due to limited access; (3) food insecurity from crop failures; and (4) mental health stress, conflict, and displacement from water competition. Women, children, and low-income households face disproportionate impacts. Current adaptation measures are fragmented, highlighting the need for integrated water governance to build climate resilience. Recommended strategies include community-based water safety planning, digital water monitoring, and embedding health metrics in climate–water policies. This cross-regional analysis supports equitable, climate-resilient health systems and informs interventions to mitigate water scarcity under accelerating climate change. This study directly supports global policy agendas by providing evidence that advances the objectives of the Sustainable Development Goals and international frameworks on climate resilience, water security, and food and health protection.

1. Introduction

Climate change is transforming global hydrological systems by altering the spatial and temporal distribution of water resources. Rising temperatures heighten atmospheric water demand, accelerate evaporation, and disrupt precipitation patterns, leading to shorter wet seasons, delayed monsoons, and more frequent extremes such as floods and droughts [1,2,3]. Large-scale climate oscillations, including the Indian Ocean Dipole and El Niño–Southern Oscillation (ENSO), further amplify hydroclimatic variability. In low- and middle-income countries, rapid population growth, urbanization, and inadequate infrastructure intensify supply–demand imbalances [4,5]. Climate-driven hydrological shifts also degrade water quality: higher temperatures foster pathogen growth and algal blooms, while extreme rainfall increases sedimentation and contamination [6]. Conversely, prolonged droughts concentrate pollutants and salinity by reducing river flows and groundwater recharge, while sea-level rise accelerates saline intrusion into coastal aquifers. These processes threaten water security for agriculture, domestic use, sanitation, and ecosystems, underscoring the need for climate-resilient governance and public health strategies [7]. Water scarcity poses complex public health challenges, influencing disease exposure, nutrition, hygiene, and healthcare delivery. Limited access to safe water forces reliance on untreated sources, increasing waterborne diseases such as cholera, diarrhea, typhoid, and hepatitis A, particularly among children and informal settlement residents [8,9]. Insufficient supply undermines hygiene practices, including handwashing and menstrual hygiene, weakening interventions during droughts or intermittent service [10]. Indirect effects include food insecurity, rising costs, and malnutrition driven by reduced agricultural productivity and livestock health, with seasonal water stress linked to stunting and undernutrition. Women and girls bear disproportionate burdens through water collection, facing physical strain, psychological stress, heightened violence risk, and reduced educational and economic opportunities. Health systems are similarly strained as shortages compromise infection control, safe childbirth, and routine care. These interconnected pathways highlight the need to embed water security within health resilience frameworks to address escalating climate-related risks [11,12].

In the context of chronic or intermittent water scarcity, households frequently depend on unsafe sources such as untreated surface water, shallow wells, or contaminated storage, increasing the burden of diarrheal and parasitic diseases. Children, older adults, and immuno-compromised individuals are disproportionately affected due to lower physiological resilience [12,13]. During health emergencies, including cholera outbreaks or pandemics, limited water access undermines sanitation, restricts handwashing, and weakens infection control. Impacts extend beyond infectious disease to include nutritional deficiencies, psychosocial stress, and pressure on healthcare systems. Reduced water availability also limits agricultural production and dietary diversity, increasing risks of undernutrition, micronutrient deficiency, and adverse long-term developmental outcomes in children, with seasonal peaks in stunting reported in rain-fed farming regions. Health facilities are similarly constrained, as water scarcity compromises hygiene, sterilization, infection prevention, and safe maternal care. Together, these processes frame water scarcity as a multidimensional public health challenge that interacts with social, economic, and infrastructural vulnerability, intensifying health inequities in climate-stressed regions [11,14,15].

A multi-regional comparative assessment is essential for understanding climate-driven water scarcity across diverse socio-ecological systems and for identifying both shared and context specific health determinants. Although South Asia, Sub-Saharan Africa, and the Middle East differ in climate and hydrology, they share vulnerabilities including rapid population growth, dependence on climate-sensitive water resources, and governance constraints. Comparative analysis enables evaluation of how institutions, cultural norms, water management, and infrastructure shape links between climatic stressors and health outcomes. It highlights common trends such as rising waterborne disease and food insecurity, while revealing regional differences that inform targeted adaptation strategies [16,17]. This perspective emphasizes the systemic and transboundary nature of climate-induced water scarcity, reflected in increasing drought, groundwater depletion, salinization, and conflict, and supports the need for coordinated resilience planning. Framing water scarcity as a global public health issue strengthens the case for integrated international action rather than isolated responses [18,19].

Figure 1 summarizes five major health impacts of prolonged drought: psychological stress linked to economic losses; shifts in disease profiles, including increased mosquito-borne and fungal infections such as Valley Fever; intensified wildfires and dust storms worsening cardiopulmonary conditions; more frequent heatwaves driving heat-related illness; and growing strain on water systems affecting households and healthcare facilities [19,20]. Concurrently, the GEOGLAM global crop-status map (July 2025) shows widespread agroclimatic stress relative to the five-year average (Figure 2), with “Watch,” “Poor,” and “Failure” classifications signaling heightened risks of yield loss and global food insecurity [21]. Together, these patterns illustrate the interconnectedness of environmental change, public health risks, and food system vulnerability, reinforcing the need for integrated, cross-sectoral adaptation strategies.

This study seeks to identify systemic factors moderating the effects of climate-driven water scarcity on public health across vulnerable socio-ecological regions. It pursues three objectives: (1) compare climate exposure and hydrological change in South Asia, Sub-Saharan Africa, and the Middle East; (2) assess water scarcity impacts on disease burden, hygiene, nutrition, mental health, and healthcare delivery; and (3) examine governance, infrastructure, and socioeconomic conditions that exacerbate or mitigate health risks. Accordingly, the research addresses four questions: How do climate-induced hydrological changes differ across regions? What are the direct and indirect health effects of water scarcity? Which behavioral, institutional, and infrastructural factors shape resilience or vulnerability? What cross-regional insights can inform integrated water, health, and climate strategies? Collectively, these inquiries provide a coherent framework for understanding the complex pathways through which climate-driven water scarcity influences public health at local and global scales. This study contributes to global policy priorities by generating evidence that directly supports international frameworks focused on climate resilience, water security, and food system stability, including the Sustainable Development Goals and related UN climate adaptation agendas. By linking climate-driven water scarcity to public health outcomes across vulnerable regions, the research strengthens the knowledge base needed for global initiatives aimed at safeguarding health, reducing environmental risk, and promoting sustainable resource governance. The study brings together a wide range of global climatic, hydrological, socioecological and public health datasets to examine climate-driven water scarcity and its related health effects. Climate variables such as temperature, rainfall and drought indicators are obtained from the NASA Earth Observing System and the NOAA Global Historical Climatology Network. Information on water availability, groundwater pressure and patterns of water use is drawn from the FAO AQUASTAT database, the WRI Aqueduct Water Risk Atlas and GRACE satellite observations. Measures of socioecological vulnerability, including population distribution, land use and poverty levels, come from UNEP and SEDAC. Data on health outcomes linked to water scarcity are sourced from the WHO Global Health Observatory and the IHME Global Burden of Disease dataset. Together, these datasets support a strong multi-regional assessment that connects climate-related water stress with public health risks across sensitive socioecological settings.

2. Conceptual Framework

This study applies a Climate Water Health framework that links hydrological and socio-environmental pathways to explain how climate variability and change affect public health. The model shows how climatic drivers such as rising temperatures, altered precipitation, and extreme events influence water availability, quality, and access, shaping outcomes like infectious disease, malnutrition, and mental health stress. Hydrological stressors including temperature rise, precipitation shifts, drought, and evapotranspiration define exposure, while socio-environmental factors such as infrastructure, governance, and demographics shape vulnerability and resilience (Figure 3). Health impacts occur through multiple routes, including pathogen exposure, poor sanitation, nutritional deficits, and psychosocial stress, with intersectional factors like gender, age, and socioeconomic status amplifying disparities. Grounded in risk governance and systems thinking, the framework supports the integrated multi-scale assessment of climate-driven water scarcity and health implications. It guides empirical design, informing site selection, indicator development, and analytical methods for coherence between theory and application.

3. Methods

3.1. Study Design and Comparative Logic

The study uses a multi-regional, comparative methodology, guided by the conceptual framework, to capture both universal and context-specific pathways connecting climate-driven water scarcity to public health consequences. The examination of causal linkages was organized and environmental, social, and health indicators were identified using the Climate–Water–Health Pathway Model. A systems-level understanding of the issue is made possible by a mixed-methods approach that integrates qualitative evaluations of governance, infrastructure, and socioeconomic mediators with quantitative hydrological and epidemiological data.

3.2. Selection of Regions

The regions were chosen to capture diverse hydro-political, socio-economic, and climatic contexts, as well as varying degrees of sensitivity to water scarcity. South Asia, Sub-Saharan Africa, and the Middle East & North Africa (MENA) exemplify high population density, drought-prone landscapes, and water systems affected by conflict, respectively (Figure 4). Guided by the conceptual framework, these locations were chosen to ensure representation of multiple socio-ecological settings while maintaining focus on exposure pathways, mediating factors, and health outcomes.

3.3. Data Sources and Inclusion Criteria

The components of the framework were operationalized through the selection of data sources. Hydrological stresses were reflected in climate and hydrological metrics derived from satellite observations, meteorological stations, and river flow datasets. Infrastructure coverage, dependability indices, and governance indicators were used to evaluate the vulnerability of the water system. WHO and UNICEF statistics, illness monitoring systems, and national health surveys were used to determine public health outcomes. To guarantee compatibility with the conceptual model, inclusion criteria were created to capture similar temporal and geographical scales across areas. To maintain consistency across all parts of the conceptual model, data sources were selected only when they met a set of clear inclusion criteria. Datasets had to align in time by covering similar reference periods, usually within the same five-year span, so that trends could be interpreted reliably. They also needed to provide national or subnational estimates at comparable administrative levels to ensure that geographical coverage was uniform across sources. In addition, all variables were required to follow widely accepted indicator definitions, such as those used by the WHO, UNICEF, or the IPCC, to allow the different datasets to be examined together. Preference was given to data sources that demonstrated strong quality assurance measures, including validated surveys, calibrated satellite observations, and official reporting systems. These conditions ensured that information on hydrology, infrastructure, governance, and public health could be integrated and evaluated consistently within the conceptual framework.

Table 1. Summary of datasets, sources, temporal and spatial resolutions, and roles in the analytical framework.

Data Category	Dataset/Indicator Type	Data Sources	Temporal Resolution	Spatial Resolution	Role in the Model/Framework
Climate and Environmental Data	Mean temperature, precipitation, evapotranspiration	ERA5 reanalysis (ECMWF), CRU TS, national meteorological agencies [23]	Monthly to annual	~0.25–0.5° gridded	Quantify climate exposure and long-term climatic trends affecting hydrological stress.
	Drought indices (SPI, SPEI, PDSI)	Global Drought Monitor, CRU, NASA datasets [24]	Monthly	~0.5° gridded	Assess frequency and intensity of drought events influencing water scarcity.
	Surface and groundwater levels	GRACE/GRACE-FO satellite data, national hydrological agencies [25]	Monthly	Basin-scale to ~1° gridded	Evaluate hydrological depletion and freshwater availability dynamics.
Hydrological and Water System Data	River discharge and runoff	Global Runoff Data Centre (GRDC), national river gauge stations [26]	Daily to monthly	River basin/station level	Represent surface water availability and hydrological variability.
	Water infrastructure coverage (piped water, boreholes)	WHO/UNICEF JMP, national water agencies [27]	Annual	National to sub-national	Assess water system capacity and population access to improved water sources.
	Water quality indicators (e.g., salinity, microbial contamination)	National water quality monitoring programs, WHO databases [28]	Annual or irregular	National to sub-national	Evaluate environmental mediators influencing disease risk pathways.
Governance and Socio-Economic Indicators	Governance and institutional capacity indices	World Bank Worldwide Governance Indicators, OECD datasets [29]	Annual	National	Represent mediating institutional and policy factors affecting vulnerability.
	Equity and distribution metrics (urban–rural access, gender disparities)	DHS, MICS, national statistics offices [30]	3–5 yearly	Sub-national	Capture socio-ecological vulnerability and differential exposure pathways.
Public Health Indicators	Waterborne disease prevalence (diarrhoea, cholera, typhoid)	WHO Global Health Observatory, national surveillance systems [31,32]	Annual to monthly	National to sub-national	Quantify health outcomes linked to water scarcity and WASH disruptions
	Nutrition indicators (stunting, wasting, anaemia)	DHS, UNICEF, FAO databases [30]	3–5 yearly	Sub-national	Assess indirect health impacts mediated through food and water scarcity.
	Mental health and psychosocial stress proxies	National health surveys, WHO mental health datasets [33]	Annual or survey-based	National to sub-national	Capture psychosocial consequences of chronic water scarcity.
Demographic and Vulnerability Data	Age- and gender-disaggregated population data	UN DESA, national census data [34]	Annual	National to sub-national	Enable intersectional vulnerability assessment and stratified health impact analysis

summarizes the primary datasets used to operationalize the conceptual framework, including climate, hydrological, governance, and public health indicators. Temporal and spatial resolutions were harmonized where possible to ensure cross-regional comparability. These datasets collectively informed the exposure, vulnerability, and health outcome components of the analytical model.

A structured search strategy was carried out across major academic databases and organizational repositories using keywords related to climate stressors, water systems, and public health. The keywords used in the structured search strategy were climate change, drought, water scarcity, groundwater depletion, waterborne diseases, and public health outcomes. Records were reviewed through a two-stage process that involved an initial screening of titles and abstracts, followed by a full-text assessment based on established inclusion criteria, such as relevance to climate, water, and health linkages, coverage of at least one of the study regions, and the availability of empirical or rigorously developed model indicators. Studies were excluded if they were not written in English, lacked empirical grounding, or did not present transparent methods. The quality of the evidence was evaluated by examining the study design, strength of data sources, validity of reported indicators, and alignment with the conceptual model. This approach ensured that the synthesis was informed only by evidence that was both methodologically sound and conceptually appropriate.

3.4. Climate Indicators and Environmental Data Metrics

Mean temperature, rainfall variability, drought indices, evapotranspiration rates, and surface and groundwater levels were among the indicators. By matching the framework’s hydrological stressors, these metrics allow for the quantitative evaluation of environmental exposure and establish a connection between climatic variability, water availability, and public health hazards.

3.5. Water System Vulnerability Metrics

Measures of infrastructure coverage, supply dependability, water quality, and sanitation access were used to evaluate the vulnerability of the water system. Regulation, equality of distribution, and institutional capability are examples of governance and management indicators that incorporated socio-environmental mediators in the framework, enabling assessment of their impact on the distribution and severity of health consequences.

3.6. Public Health Indicators and Surveillance Data

The prevalence of diarrheal illnesses, cholera, typhoid, nutritional markers (stunting, wasting, anemia), and mental health proxies like stress and psychosocial strain were among the health outcomes chosen to operationalize the model’s pathways. To represent intersectional vulnerabilities, age-specific and gender-disaggregated data were given priority. Public health indicators were derived from nationally reported surveillance systems, demographic and health surveys, WHO/UNICEF databases, and peer-reviewed epidemiological studies. These sources provide standardized, population-level data collected using validated protocols, which enhances their comparability and reliability. However, variations in reporting quality, timeliness, and subnational coverage introduce some uncertainty. To mitigate this, priority was given to datasets with established methodological rigor and age- and gender-disaggregated estimates to strengthen the accuracy of modeled intersectional vulnerabilities.

3.7. Analytical Approach and Cross-Regional Comparison Strategy

Climate and water variables were linked to health outcomes by quantitative studies such as regression, correlation, and geographical mapping. The interpretation of causal pathways was guided by the conceptual framework, and regional comparisons revealed both context-specific differences and universal trends. System-level insights were made easier by triangulating qualitative governance and infrastructure data.

3.8. Ethical Considerations and Study Limitations

Ethical approval was not applicable for this study because it relied exclusively on secondary, publicly available datasets and did not involve the collection of new human participant data. The framework prioritized equity and intersectionality, focusing ethical considerations on vulnerable populations. Despite a robust comparative approach, limitations remain. Regional data variability (such as differences in measurement standards, temporal resolution, and monitoring capacity) complicates comparisons. Incomplete long-term records, especially in Sub-Saharan Africa, affect temporal modelling accuracy. Socioeconomic overlaps, policy contexts, and infrastructure disparities make it difficult to isolate health impacts from climate-driven water scarcity. Dependence on secondary data further restricts independent validation. Heterogeneity and incomplete reporting in the secondary datasets constrained rigorous model calibration and validation, and thus the regression and correlation analyses are intended primarily for analysis rather than predictive performance. These challenges were addressed through transparent reporting, sensitivity checks, and triangulation across multiple sources.

The study workflow begins with the collection and preprocessing of climate, hydrological, socioeconomic, and health datasets, followed by the application of regression and correlation models to analyze key relationships across the selected regions (Figure 5). The validated models are then used to assess health impacts associated with climate-driven water scarcity, leading to the final interpretation and reporting of region-specific findings.

4. Results

4.1. Regional Climate Exposure and Water Scarcity Dynamics

4.1.1. South Asia

• Climate Trends

Driven by climate change and shifting atmospheric dynamics, South Asia has experienced a clear warming trend over recent decades alongside growing variability in precipitation patterns. Regional assessments indicate rising mean annual temperatures across the subcontinent, with high-emission scenarios projecting an additional 0.44–0.69 °C by the 2030s and up to 1.3–2.0 °C by mid-century. This warming has intensified extreme heat events, exemplified by the 2025 India–Pakistan heatwave, which recorded unprecedented daily maxima [35,36,37]. Precipitation regimes have become increasingly erratic, marked by delayed onset, uneven spatial distribution, and abrupt shifts between heavy rainfall and prolonged dry spells. The classical monsoon system (historically responsible for most annual rainfall) is now less predictable, undermining water supply reliability for drinking, sanitation, and agriculture. Rising temperatures combined with irregular rainfall alter not only long-term climatic norms but also the timing and quality of water flows, with significant implications for agricultural cycles, groundwater recharge, and seasonal water security for millions across the subcontinent [38,39,40,41].

2.

Hydrological Pressures

Surface and groundwater systems in South Asia are under mounting hydrological stress due to documented climatic trends. Recent studies show marked declines in seasonal precipitation and wet days across major river basins such as the Ganga, particularly during pre-monsoon and monsoon periods, alongside rising evapotranspiration (ET) rates. These shifts strain seasonal streams and perennial rivers, intensifying hydrological and meteorological droughts through prolonged dry spells and reduced surface water availability. Accelerated glacier retreat further destabilizes river flow in snow-fed basins, undermining meltwater reliability [42,43,44]. Groundwater, traditionally a buffer against surface water variability, is also under severe pressure. Extraction has surged as surface water becomes less predictable and demand rises from urbanization, agricultural intensification, and population growth, while recharge declines due to reduced rainfall and higher evaporation. Local studies report falling well yields and worsening scarcity as perceived by farmers and communities. Over-extraction without adequate recharge is depleting aquifers, eroding long-term water security and resilience. Combined stresses (diminishing river flows, erratic monsoon recharge, and declining aquifers) heighten water scarcity risks in both rural and urban areas [45,46,47,48].

3.

Urban–Rural Water Scarcity Patterns

In South Asia, climate-driven hydrological stress manifests differently across rural and urban areas, though both face severe water scarcity risks. In rural regions, erratic monsoon rains disrupt crops and livestock production, threaten livelihoods, and reduce household water availability for domestic use, sanitation, and hygiene (especially where agriculture is rain-fed and infrastructure is limited) [48,49,50]. Families often depend on wells or streams; declining groundwater and reduced flows lead to intermittent supply, affecting both agricultural output and basic needs such as drinking and cooking. Over-extraction and a lack of alternative sources further exacerbate rural water scarcity [51,52]. Urban areas face distinct pressures. Rapid population growth and unplanned urbanization drive rising water demand amid increasingly unreliable supply. Infrastructure often fails to meet demand, resulting in rationing, periodic shortages, or reliance on costly and unsafe sources. Expansion into recharge zones and floodplains impairs natural replenishment. Poor communities are most vulnerable, lacking secure connections or storage capacity, particularly during droughts or dry seasons. These contrasting rural and urban patterns underscore the need for climate-resilient strategies and context-specific water management tailored to settlement type and resource stress [53,54,55].

4.1.2. Sub-Saharan Africa

1.

Temperature and Rainfall Variability

Sub-Saharan Africa is experiencing marked shifts in temperature and rainfall variability, reshaping hydrological baselines and stressing water resources. Rising surface temperatures increase potential evapotranspiration, reducing net water availability, especially in semi-arid and dry zones. Rainfall patterns have grown less predictable in timing and intensity, with altered onset, uneven spatial distribution, and greater interannual variability. This combination of warming and erratic rainfall undermines traditional water renewal and storage systems. Surface water bodies and soils struggle to maintain stable supplies due to higher evaporation and fewer recharge events, heightening scarcity risks [56,57,58]. Slow-onset climatic changes and rainfall unpredictability create complex risk dynamics. Water stress may rise even where rainfall remains near historical averages because temperature-driven evaporation offsets gains, making precipitation totals an unreliable indicator of water security. This decoupling complicates resource planning and risk assessment. Studies confirm that increased evapotranspiration and irregular rainfall reduce effective water availability (the usable water after losses), altering long-term hydrological regimes across catchments. These fluctuations severely compromise water reliability for drinking, sanitation, agriculture, and ecosystems, particularly for vulnerable communities reliant on surface water and rain-fed cycles [59,60,61,62].

2.

Drought Cycles and Surface Water Decline

Sub-Saharan Africa is witnessing marked changes in the frequency, severity, and spatial variability of hydrological droughts across multiple basins. A continental-scale analysis of streamflow records from 1466 gauging stations (1951–2018) indicates a significant shift beginning in the 1980s, with droughts becoming more frequent, prolonged, and severe in several central and eastern regions [63,64]. Surface water systems (rivers, streams, and wetlands), once reliable sources, now exhibit reduced flows or seasonal dry-outs during extended droughts. This trend threatens water security in rural and peri-urban areas dependent on surface water for domestic, agricultural, and livestock needs [65,66]. Natural storage systems such as aquifers, shallow wells, and wetlands are similarly compromised by low-flow periods and reduced precipitation recharge. Recurrent droughts diminish water volume, degrade quality, and accelerate salinization and eutrophication, further limiting usable resources, as confirmed by remote sensing and climate modelling studies. These pressures drive long-term scarcity, intensify competition for remaining water, and force reliance on unsafe or distant sources. Frequent drought cycles weaken resilience and slow recovery, deepening water scarcity across vulnerable communities [67,68,69].

3.

Seasonal Water Stress and Resource Conflicts

Many regions of Sub-Saharan Africa face acute seasonal water stress, where demand exceeds supply during dry seasons and drought years. This stress stems from climatic variability, recurrent droughts, and declining surface water availability, affecting rural agricultural zones as well as peri-urban and urban areas with limited infrastructure. Seasonal shortages disrupt livelihoods, food security, and public health by restricting water access for rain-fed agriculture, domestic use, sanitation, and livestock, often worsening food insecurity, malnutrition, and waterborne or hygiene-related diseases [66,70,71]. Water scarcity also heightens competition among urban users, pastoralists, and farmers, frequently triggering conflict or displacement. These pressures are compounded by weak governance, institutional gaps, and inadequate water management and infrastructure. Population growth, economic marginalization, and climate stress further drive inequitable access, disproportionately affecting vulnerable groups and eroding public health resilience [71,72,73,74].

Water scarcity in Sub-Saharan Africa represents a structural, climate-driven crisis shaped by temperature and rainfall variability, recurrent droughts, and surface water depletion. These hydrological changes threaten the reliability of surface and groundwater resources, while socioeconomic and governance constraints limit adaptive capacity. From a public health perspective, risks linked to waterborne disease, inadequate hygiene, malnutrition, and social instability are likely to intensify under ongoing climate stress [66,69,74]. Addressing these challenges requires integrated, climate-resilient water governance, improved monitoring, targeted infrastructure investment, and conflict-sensitive resource allocation, with emphasis on vulnerable populations and institutional capacity-building. Overall, this synthesis illustrates how climate-driven hydrological stress translates into tangible public health risks across Sub-Saharan Africa [66,75].

4.1.3. MENA

1.

Long-Term Precipitation Declines

The MENA region has experienced long-term declines in precipitation, altering its hydrological and ecological baseline. Multi-decade reductions in annual rainfall have been documented in countries such as Morocco, Algeria, Tunisia, Jordan, and Syria, compounded by increasing variability in seasonal distribution. Winter rainfall (critical for replenishing rivers, aquifers, and agricultural soils) has become shorter and more irregular, accelerating rangeland degradation, reducing soil moisture, and increasing reliance on groundwater. Consequently, renewable freshwater resources that once sustained rural and peri-urban livelihoods are steadily diminishing [18,76,77]. Climate projections under medium- and high-emission scenarios indicate further precipitation declines across MENA, with the Mediterranean basin and Arabian Peninsula among the most affected globally. Rising temperatures amplify these trends by increasing evaporation and reducing rainfall effectiveness, pushing hydrological systems toward chronic deficits where annual precipitation cannot sustain recharge or ecological function. This structural scarcity heightens vulnerability to drought, water stress, and associated public health risks, as natural regeneration fails to meet growing socioeconomic demand [18,78,79].

2.

Groundwater Depletion Trend

Groundwater depletion has emerged as one of the most critical water challenges in the MENA region, with reported declines in groundwater levels typically ranging from 0.5 to 3.0 m per year and exceeding 5 m per year in intensively irrigated aquifers (e.g., parts of Saudi Arabia, Iran, and North Africa). These declines are primarily driven by agricultural over-extraction, reduced recharge due to climate variability, and increasing domestic and industrial water demand [80,81]. Reduced precipitation and altered flow patterns have curtailed aquifer recharge, while reliance on extraction has grown. In countries such as Saudi Arabia, Iran, Yemen, and Libya, deep fossil aquifers (formed under ancient climatic conditions) are being exploited at rates far exceeding natural replenishment. Although this has enabled short-term agricultural expansion, it has produced unsustainable trends, with water tables in some basins falling by several meters annually [80,82,83].

Declining groundwater levels lead to deteriorating water quality, rising salinity, higher pumping costs, and the drying of shallow wells that once served as local safety nets. Coastal aquifers, particularly in North Africa and the eastern Mediterranean, face increased seawater intrusion, further compromising potable water supplies. These depletion patterns threaten agricultural productivity and household water security, especially in rural and peri-urban areas with limited infrastructure. Structural scarcity is compounded as falling precipitation reduces surface water while escalating withdrawals (driven by food security pressures and population growth) exceed sustainable aquifer capacity. This trajectory raises the risk of irreversible groundwater collapse in some sub-regions, with profound implications for water governance and public health resilience [84,85,86].

3.

Agricultural and Domestic Water Demand Pressures

Agriculture accounts for 80–90% of freshwater withdrawals in many MENA countries, making it the dominant driver of water demand. Population growth and dietary shifts have intensified pressure on agricultural systems, prompting governments to expand irrigation or boost crop yields in water-scarce regions. Despite limited resources and inefficient irrigation networks, water-intensive crops such as wheat, lucerne, and dates remain widely cultivated. This mismatch deepens water deficits: high evaporation, flood irrigation, and outdated canals cause major losses, reducing water availability for domestic and ecological needs. Agricultural expansion also disrupts groundwater recharge zones, accelerating soil degradation and aquifer depletion [81,87,88,89]. Urban water demand is rising due to rapid urbanization, higher living standards, and population growth. Cities such as Cairo, Amman, Casablanca, and Riyadh face mounting supply challenges from aging infrastructure, leakage, and intermittent delivery. Utilities struggle to balance provision between informal settlements (where access is unreliable or dependent on costly private vendors) and affluent neighborhoods with secure connections. During droughts or seasonal shortages, authorities prioritize drinking water over irrigation, intensifying rural–urban competition and disrupting food production, often triggering economic shocks. These pressures exacerbate structural water scarcity and underscore the urgent need for integrated water management and climate-resilient policies [45,89,90,91].

4.1.4. Concluding Synthesis Across South Asia, Sub-Saharan Africa, and MENA

Across South Asia, Sub-Saharan Africa, and MENA, long-standing structural vulnerabilities are being amplified by climate-driven hydrological stress, creating complex water scarcity that increasingly threatens socioeconomic stability and public health. While each region exhibits distinct climatic features (South Asia’s monsoon volatility, Sub-Saharan Africa’s rainfall variability and recurrent droughts, and MENA’s chronic precipitation decline and extreme aridity), their water systems share convergent trends: intensifying seasonal stress, accelerated groundwater depletion, and declining surface water reliability [92,93]. Rapid population growth, agricultural dependence, inadequate infrastructure, and governance constraints compound these pressures, driving household and agricultural deficits, increasing exposure to waterborne diseases, and worsening nutrition and hygiene-related health risks. Socio-political dimensions of scarcity appear in rural–urban inequities in South Asia, pastoralist–farmer conflicts in Sub-Saharan Africa, and agricultural–domestic trade-offs in MENA. Collectively, these patterns show that, despite regional differences, climate-related water scarcity is systemic and interconnected, requiring integrated, climate-resilient water governance, robust public health systems, and cross-regional knowledge sharing to protect vulnerable populations [45,88,94]. Distinct indicators of water and climate stress differ across regions. South Asia experiences a moderate reduction in rainfall along with pronounced monsoon variability, Sub-Saharan Africa faces rising drought frequency and considerable rainfall fluctuation, and the MENA region shows a continued decline in precipitation together with some of the most severe groundwater loss recorded worldwide (Table 2).

Table 2. Comparative hydroclimatic stress indicators across regions.

Region	% Decline in Mean Annual Rainfall	% Increase in Drought Frequency/Intensity	Groundwater Table Decline (m yr−1)	Key References
South Asia	5–15% decline in some basins; increased variability	10–30% increase in drought frequency and severity (1981–2022)	0.2–1.0 (localized hotspots > 1.5)	[95,96,97,98]
Sub-Saharan Africa	5–10% decline in southern Africa by mid-century	2.5–3 additional drought events per decade since 1961	0.1–0.5 (hotspots up to 1.0)	[99,100,101]
Middle East & North Africa (MENA)	5–20% projected decline by 2050	20–40% increase in drought frequency and severity	0.5–3.0 (intensive aquifers > 5.0)	[102,103,104]

Table 2. Comparative hydroclimatic stress indicators across regions.

Region	% Decline in Mean Annual Rainfall	% Increase in Drought Frequency/Intensity	Groundwater Table Decline (m yr−1)	Key References
South Asia	5–15% decline in some basins; increased variability	10–30% increase in drought frequency and severity (1981–2022)	0.2–1.0 (localized hotspots > 1.5)	[95,96,97,98]
Sub-Saharan Africa	5–10% decline in southern Africa by mid-century	2.5–3 additional drought events per decade since 1961	0.1–0.5 (hotspots up to 1.0)	[99,100,101]
Middle East & North Africa (MENA)	5–20% projected decline by 2050	20–40% increase in drought frequency and severity	0.5–3.0 (intensive aquifers > 5.0)	[102,103,104]

4.1.5. Cross-Regional Comparison

The comparison matrix offers a clear and verifiable overview of how South Asia, Sub-Saharan Africa, and the MENA region differ and overlap across major climate exposures, water system pressures, social vulnerabilities, and public health outcomes (Table 3). It brings together evidence showing that all three regions are warming faster than the global average, although each displays distinct climate patterns, such as monsoon instability in South Asia, recurring drought in Sub Saharan Africa, and persistent aridity across MENA. Table 3 also reveals shared challenges, including falling groundwater levels, reduced reliability of surface water, and growing risks to water quality, alongside structural vulnerabilities related to governance constraints, poverty, conflict, and social inequality. By linking these regional stressors with documented health outcomes such as diarrhea, cholera, malnutrition, heat stress, and psychological strain, the table strengthens the comparison and provides a more complete understanding of how climate pressures influence water security and public health across different regions.

1.

Common Climate Stressors.

Multiple climatic stressors converge in South Asia, Sub-Saharan Africa, and the MENA region, with warming rates exceeding the global mean. Recent assessments indicate temperature increases of approximately 0.2–0.4 °C per decade in South Asia, 0.3–0.5 °C per decade in Sub-Saharan Africa, and 0.4–0.6 °C per decade in the MENA region, compared to a global average of ~0.2 °C per decade. This accelerated warming is associated with 5–20% increases in potential evapotranspiration, 5–30% reductions in streamflow in vulnerable basins, and significant declines in soil moisture, thereby exacerbating water scarcity and related public health risks [104,105]. These warming trends combine with rainfall variability (irregular monsoons in South Asia, unpredictable wet and dry season shifts in Sub-Saharan Africa, and long-term precipitation decline in MENA), driving hydrological extremes such as droughts and flash floods. These conditions undermine water storage and disrupt sanitation systems, creating cascading effects on vector ecology, food security, and waterborne disease exposure [106,107]. Prolonged drought cycles degrade ecosystems and weaken surface and groundwater resilience. In South Asia, drought compounds shortages linked to dense populations and irrigation-intensive farming; in Sub-Saharan Africa, it interacts with rain-fed agriculture and poor infrastructure; and in MENA, it worsens chronic aridity and over-abstraction. These stressors push vulnerable systems toward chronic scarcity. This convergence highlights the need for cross-regional adaptation strategies emphasizing resilience-based water governance, diversified supply systems, and advanced hydrological risk forecasting [44,108,109].

2.

Divergence in Hydro-Political Contexts

Although South Asia, Sub-Saharan Africa, and MENA share similar climate stresses, their hydro-political contexts differ markedly, shaping water scarcity trajectories and population impacts. In South Asia, disputes focus on transboundary rivers such as the Ganges–Brahmaputra–Meghna and Indus basins, where competing domestic, hydroelectric, and agricultural demands fuel interstate tensions. Fragmented local governance combined with strong national water agencies produces uneven adaptation and inconsistent health outcomes. Sub-Saharan Africa, by contrast, depends heavily on shared rivers like the Niger, Nile, and Zambezi but faces limited institutional capacity and weak basin-level coordination. Inadequate cooperation frameworks hinder integrated drought management, equitable allocation, and long-term planning, increasing vulnerability to climate variability [110,111,112,113]. MENA presents a third scenario, marked by severe geopolitical tensions, reliance on shared aquifers, and some of the world’s highest transboundary water dependence. In countries such as Jordan, Israel, Palestine, Iraq, and Syria, water scarcity intersects with political instability, migration pressures, and governance deficits, elevating its status as both an environmental and security challenge. While MENA has advanced desalination and water-transfer technologies compared to Sub-Saharan Africa, systemic fragility persists due to governance failures, protracted conflicts, and limited groundwater renewability. These contrasting hydro-political settings illustrate how similar climatic stresses produce divergent patterns of scarcity and public health risk [88,111,114].

3.

Regional Exposure Overlaps

Despite institutional and ecological differences, South Asia, Sub-Saharan Africa, and MENA exhibit overlapping exposure patterns that reveal common vulnerability pathways. Rising temperatures, declining per capita water availability, and growing dependence on groundwater due to unreliable surface water systems increase risks of diarrheal disease, malnutrition, and heat-related illness. Shared challenges include aquifer over-extraction, land subsidence, and contamination of shrinking water bodies. Rural communities are disproportionately affected by inadequate infrastructure, poor sanitation coverage, and limited access to adaptive technologies such as drip irrigation, water purification, and climate-smart agricultural inputs [108,115,116]. Urban areas, from Delhi to Lagos to Cairo, face similar pressures from rapid population growth, rising water demand, and reliance on informal water vendors. These dynamics heighten vulnerability among low-income groups and exacerbate socioeconomic disparities in water access. Inadequate wastewater treatment further increases pathogen exposure, disrupts service delivery during heatwaves, and contaminates supply networks in informal settlements. Collectively, these overlaps demonstrate that, despite diverse hydro-political and ecological contexts, the three regions share converging climate-driven pathways that produce comparable water scarcity and public health risk profiles [117,118].

Table 3. Cross-regional comparison matrix.

Category	South Asia	Sub-Saharan Africa (SSA)	Middle East & North Africa (MENA)
Core Climate Exposures	Increasing temperatures across Asia faster than the global average; intensified heatwaves and droughts; monsoon circulation weakening and increasing variability [119]	Surface temperatures in Africa rising more rapidly than the global average; increasing hot extremes and hydrological droughts [120]	MENA warming two to three times faster than the global average in several areas; predicted summer temperature increases up to 4 °C by 2071–2100; persistent aridity [121]
Water-System Responses	Increased evapotranspiration pressures and declining water availability; strong regional variation due to irrigation effects [122]	River flow reduction, groundwater stress, and regionwide hydrological droughts; widespread WASH service gaps heighten water-quality risks [120]	Severe groundwater depletion, extremely low renewable surface water, salinisation and reduction in water quality in arid zones [104]
Key Vulnerabilities	High climate-related health risks linked to extreme heat, floods, and storms; rapid population exposure to climate hazards [119]	High vulnerability to drought, poverty, conflict, and food insecurity; climate impacts exacerbating displacement and livelihood loss [120,123]	Water scarcity among the most severe globally; governance stress, political fragility, and exposure to extreme heat and drought [124]
Major Health Outcomes	Heat-related stress, increased risk of waterborne disease outbreaks, and widespread disaster-related health impacts [119]	High incidence of diarrheal disease, malnutrition in drought-affected regions, and heat-related illnesses [124]	Rising heat-related illness, waterborne disease risks from declining water quality, and worsening mental-health strain due to chronic water scarcity [125,126].

Table 3. Cross-regional comparison matrix.

Category	South Asia	Sub-Saharan Africa (SSA)	Middle East & North Africa (MENA)
Core Climate Exposures	Increasing temperatures across Asia faster than the global average; intensified heatwaves and droughts; monsoon circulation weakening and increasing variability [119]	Surface temperatures in Africa rising more rapidly than the global average; increasing hot extremes and hydrological droughts [120]	MENA warming two to three times faster than the global average in several areas; predicted summer temperature increases up to 4 °C by 2071–2100; persistent aridity [121]
Water-System Responses	Increased evapotranspiration pressures and declining water availability; strong regional variation due to irrigation effects [122]	River flow reduction, groundwater stress, and regionwide hydrological droughts; widespread WASH service gaps heighten water-quality risks [120]	Severe groundwater depletion, extremely low renewable surface water, salinisation and reduction in water quality in arid zones [104]
Key Vulnerabilities	High climate-related health risks linked to extreme heat, floods, and storms; rapid population exposure to climate hazards [119]	High vulnerability to drought, poverty, conflict, and food insecurity; climate impacts exacerbating displacement and livelihood loss [120,123]	Water scarcity among the most severe globally; governance stress, political fragility, and exposure to extreme heat and drought [124]
Major Health Outcomes	Heat-related stress, increased risk of waterborne disease outbreaks, and widespread disaster-related health impacts [119]	High incidence of diarrheal disease, malnutrition in drought-affected regions, and heat-related illnesses [124]	Rising heat-related illness, waterborne disease risks from declining water quality, and worsening mental-health strain due to chronic water scarcity [125,126].

4.2. Implications for Water Systems and Access

4.2.1. Declining Surface Water Resources

Long-term drought cycles, rising temperatures, and declining river inflows have significantly reduced perennial streams and reservoir storage, driving a sustained decline in surface water resources across MENA. Major basins such as the Jordan and Euphrates–Tigris have experienced multi-decadal flow reductions due to upstream withdrawals and climate change, limiting agricultural allocations, hydropower generation, and the buffering capacity of dams during heat extremes. As reservoir volumes shrink, communities increasingly depend on intermittent surface water deliveries, heightening vulnerability to supply shocks during peak irrigation seasons [89,118,127]. Ecological impacts include wetland degradation, riparian vegetation loss, and declining waterbird populations, weakening natural purification processes and watershed resilience. Continued upstream flow reductions place additional stress on urban centers reliant on surface transfers (such as Amman and Damascus), forcing rationing and alternative sourcing. The diminishing availability of renewable surface water accelerates reliance on desalination and groundwater abstraction, increasing dependence on costly, energy-intensive alternative [128,129].

4.2.2. Groundwater Stress and Over-Extraction

Groundwater in the MENA region faces severe stress from over-extraction that consistently exceeds natural recharge rates. Aquifer depletion has accelerated in countries such as Saudi Arabia, Yemen, Jordan, and Iran due to rising withdrawals for agriculture, industry, and urban expansion. Many aquifers (particularly fossil groundwater systems) are essentially non-renewable on human timescales, making current extraction practices equivalent to long-term resource liquidation. Falling water tables have reduced productivity, increased pumping costs, and necessitated deeper boreholes, further straining energy and financial resources [80,83]. Water quality deteriorates as depletion triggers salinity increases, brine intrusion, and mobilization of geogenic contaminants such as arsenic and fluoride. Rural communities relying on shallow communal wells are most affected, as declining water tables render these sources ineffective for basic household needs. Overuse of groundwater has also intensified social conflicts in parts of Yemen and Libya, where agricultural users, tribes, and local authorities compete for dwindling reserves. The cumulative impact of excessive extraction threatens groundwater’s role as a drought buffer, undermining long-term water security and resilience [83,89].

4.2.3. Water Quality Degradation and Contamination Pathways

Water quality degradation has become a major challenge across MENA, driven by industrial discharge, untreated urban wastewater, agricultural runoff, and salinization. Rivers and canals (particularly in Iraq, Egypt, and Iran) show high concentrations of nutrients, pathogens, and heavy metals, compromising both drinking water safety and agricultural suitability. Reduced natural flow diminishes dilution capacity, while high evaporation concentrates pollutants, increasing toxicity and rendering many water bodies unfit for use. Heatwaves further exacerbate this through frequent algal blooms, complicating treatment for urban utilities [130,131]. Groundwater contamination is also rising, especially where over-extraction induces saline intrusion or draws untreated effluent from leaking sewage systems. In informal settlements, septic pits often pollute shallow wells, heightening risks of diarrhea and other health issues. Severe salinity and nitrate contamination in coastal aquifers (such as Gaza, Tunisia, and Oman) threaten long-term water security for millions. Combined effects of pollution and scarcity increase treatment costs and technological complexity, deepening inequalities in access to safe drinking water [132,133].

4.2.4. Urban Water Supply Intermittency

Urban water supply in MENA is increasingly marked by intermittent distribution due to resource scarcity, population growth, and aging infrastructure. In cities such as Amman, Sana’a, Cairo, and Baghdad, piped water is delivered on rotational schedules ranging from every few days to biweekly. This intermittency forces households to depend on rooftop tanks, private vendors, or bottled water—often at significantly higher cost. Irregular flow also raises contamination risks, as negative pressure in pipes enables infiltration of polluted groundwater or wastewater into networks [89,134]. Intermittent supply imposes cascading socio-economic burdens, particularly on low-income households lacking adequate storage or purification systems. Disruptions affect schools, healthcare facilities, and food processing, compromising hygiene and operational reliability. Utilities incur financial losses from pipe corrosion, water loss, and inefficiencies. Without major investment in infrastructure resilience, leakage control, and alternative supply systems, urban intermittency is expected to worsen under accelerating climate change and population growth [91,135].

4.2.5. Water Infrastructure Gaps in Rural Settings

Persistent infrastructural deficiencies significantly limit fair access to clean drinking water in rural areas throughout the Middle East and North Africa. Many communities rely on manually dug wells, tinkered supplies, or seasonal streams that are extremely susceptible to climate-induced fluctuation because they lack effective piped networks. Low investment in rural water systems causes frequent service disruptions, inadequate treatment capacity, and high system failure rates in nations like Yemen, Sudan, and Morocco. By forcing households to rely on risky sources that expose them to microbial contamination and waterborne illnesses, this infrastructure deficit compromises public health [136,137]. Rural farmers have decreased climatic resilience, and agricultural inefficiencies are also caused by the lack of dependable irrigation infrastructure. Rural households cannot protect themselves from drought cycles or adjust to changing rainfall patterns without access to controlled canal systems, drip irrigation, or contemporary storage facilities. Additionally, even recently built infrastructure deteriorates rapidly due to poor local government and poor upkeep. As rural populations migrate to cities in pursuit of more dependable water availability, these disparities exacerbate rural–urban inequality and increase migratory pressures [138,139].

4.2.6. Water Allocation Inequality and Governance Failures

Inadequate governance, institutional fragmentation, and unfair distribution methods frequently influence how water is allocated in the MENA regions. Even when efficiency is poor, agricultural sectors receive disproportionately large allocations in many nations, underserving urban and environmental requirements. Unmonitored pumping, illicit well drilling, and informal extraction are all made possible by lax regulatory enforcement, which speeds up the depletion of resources. In weak and conflict-affected governments like Yemen, Syria, and Libya, where institutional breakdown threatens coordinated water planning and equal distribution across communities, governance failures are especially severe [114,140,141]. Particularly in areas where political or tribal groups control access to irrigation channels or wells, these structural flaws increase the likelihood of conflict and worsen socioeconomic injustices. Allocation choices are made more difficult by political disputes over transboundary waters, such as the Euphrates, Nile, and Jordan systems, which frequently prioritize national security concerns above fair family access. Inadequate data systems, a lack of openness, and corruption in the acquisition of water infrastructure are more examples of governance weakness. In the end, these mistakes exacerbate stressors brought on by climate change and obstruct the creation of robust, inclusive water management systems [70,142].

4.2.7. Emerging Digital Water Monitoring Innovations

Despite structural challenges, the MENA region is increasingly adopting digital water monitoring solutions to improve resource management. Countries such as the United Arab Emirates, Israel, Jordan, and Saudi Arabia are deploying smart meters, IoT sensor networks, and satellite-based evapotranspiration monitoring to detect leakage, optimize demand, and enhance irrigation scheduling. These technologies strengthen situational awareness under climatic variability and assist utilities in managing scarce resources [138,143]. Advances in automated well monitoring, real-time aquifer modelling, and remote sensing further support groundwater management by providing accurate extraction and recharge data, enabling early detection of unsustainable pumping. Precision irrigation tools and soil-moisture sensors help farmers conserve water while sustaining yields. However, access remains uneven, particularly in rural and low-income areas [144,145]. MENA’s water security landscape remains complex, shaped by declining surface water, groundwater over-extraction, deteriorating quality, intermittent urban supply, governance gaps, and emerging digital innovations. Climate-driven hydrological stress exacerbates structural weaknesses, widening disparities between urban and rural populations and across socioeconomic groups. While digital monitoring and precision management offer efficiency gains, they cannot offset accelerating depletion of renewable and fossil water sources without parallel reforms in allocation policies, infrastructure investment, and regulatory enforcement. Ultimately, converging political, socioeconomic, and climatic pressures demand coordinated, multi-scale strategies to stabilize supply, safeguard public health, and build resilience amid growing uncertainty [146,147].

4.3. Public Health Implications of Climate-Driven Water Scarcity

4.3.1. Waterborne Diseases

1.

Diarrheal Disease Burden

Due to decreased availability of clean drinking water, worsening water quality, and decreased hygiene habits during times of severe shortage, climate-driven water scarcity greatly increases the burden of diarrheal illnesses across fragile socio-ecological systems. Communities, especially those in rural and informal settlements, are depending increasingly on unimproved or polluted water sources as surface water supplies decrease and groundwater tables drop. Inadequate sanitation systems, which frequently malfunction under drought circumstances due to effluent becoming concentrated and inadequately diluted, exacerbate this vulnerability. Children under five are disproportionately affected by the ensuing increase in microbial contamination, which includes E. coli, Giardia, and Cryptosporidium. These recurrent diarrheal diseases cause stunting, malnutrition, and higher mortality [81,148]. Households are also less able to maintain basic hygienic practices like food cleaning, hand washing, and disposing of sanitary waste when there is a shortage of water. Many communities prioritize water for cooking and drinking during protracted droughts, which results in inadequate hygiene practices that increase the risks of disease transmission. The environmental persistence of enteric pathogens and microbial growth rates increase with warmth, increasing exposure even in the presence of water. The cyclical and frequent seasonal pattern of diarrheal illness prevalence is eventually reinforced by climatic factors that deteriorate both water quantity and quality, as shown by these dynamics [149,150].

2.

Cholera, Typhoid, and Dysentery Trends

Persistent water scarcity, combined with overcrowding, poor sanitation, and reliance on contaminated sources, creates ideal conditions for outbreaks of cholera, typhoid fever, and dysentery. Vibrio cholerae often concentrates in stagnant or slow-flowing waters during reduced river flows, closely linked to cholera epidemics. In South Asia and Sub-Saharan Africa, degraded pipe networks and intermittent supply facilitate cross-contamination between drinking water and sewage lines [151,152]. Typhoid and dysentery also rise as households depend on shallow wells, irrigation canals, or riverbank filtration, which are highly vulnerable to fecal contamination, especially during heatwaves or drought-induced low flows. Scarcity-driven migration, such as urban influx after crop failure, increases population density in settlements with inadequate sanitation and health services, amplifying transmission. Epidemics frequently follow water system collapse or reduced humanitarian supply in refugee and internally displaced communities across MENA and East Africa. These risks are compounded by growing antibiotic resistance in Shigella and Salmonella typhi, prolonging illness and sustaining environmental contamination. Combined effects of pathogen evolution, infrastructure failure, and climate stress accelerate the geographic spread and seasonal resurgence of waterborne enteric infections [9,11,153,154,155].

3.

Disease Seasonality and Outbreak Dynamics

As climate change modifies rainfall patterns, lengthens dry periods, and increases wet-season floods, disease seasonality in aquatic illnesses is becoming increasingly noticeable. Reduced water supply during dry spells pushes people to rely on contaminated sources, which raises the prevalence of diarrheal illnesses and causes occasional outbreaks. Acute surges in disease incidence are caused by high runoff that eventually brings sewage, germs, and accumulated waste into rivers and shallow aquifers. These two peaks, one caused by abrupt hydrological flushing and the other by shortages, result in a prolonged transmission window that overwhelms regional health systems and makes outbreak prediction more difficult [9,11]. Outbreak dynamics are further affected by increasing temperatures, which accelerate microbial reproduction and boost pathogen survivability in both water distribution systems and open habitats. Heatwaves increase evaporation and concentrate pollutants in remaining water bodies, creating conditions for explosive cholera, typhoid, and dysentery outbreaks when there is little rainfall or supply interruptions. Since stored domestic water provides a reservoir for bacterial growth and pressure variations allow pathogen entry into networks, urban areas with intermittent water supplies see particularly acute outbreak cycles. The necessity for integrated water-health surveillance systems that can predict disease risks under changing hydrological regimes is highlighted by these climate-modulated seasonal dynamics [11,156,157].

4.3.2. Hygiene and Sanitation Challenges

1.

Handwashing and Household Hygiene Constraints

Climate-driven water scarcity directly undermines household hygiene practices, particularly handwashing frequency and effectiveness. When water becomes limited or costly, households prioritize drinking and cooking, leaving insufficient water for routine hygiene. This shift heightens exposure to fecal–oral infections, especially in low-income or densely populated areas where shared sanitation facilities already pose contamination risks. Sporadic piped supply and reliance on stored water (often inadequate or contaminated) further exacerbate the problem during droughts or urban supply disruptions. Even when soap and hygiene products are available, their effectiveness is severely compromised without sufficient water [69,81,150]. Water scarcity also impedes cleaning of utensils, food preparation areas, and personal items, increasing diarrhea and enteric disease transmission. Women and children, typically responsible for water collection, bear disproportionate burdens as longer trips reduce time and water for hygiene. In desert settings, coping strategies such as limiting washing, recycling wastewater, or substituting conventional cleaning methods often elevate microbial exposure. These constraints illustrate how climate-amplified scarcity erodes even the most basic preventive health practices [158,159,160].

2.

Sanitation Infrastructure Stress

Water scarcity places severe strain on sanitation systems, reducing infrastructure resilience and functionality. Water-dependent systems (such as sewage networks and flush toilets) are particularly affected, as inadequate supply causes blockages, backflow, and stagnation, creating contamination hotspots and fostering pathogen growth. Loss of hydraulic pressure in areas with intermittent supply enables wastewater infiltration into drinking water networks, heightening public health risks. During droughts, poorly maintained or unlined pit latrines become hazardous as dryness causes cracks and leaks that contaminate shallow wells [161,162]. Similar challenges affect rural sanitation, where households rely on on-site solutions like pit latrines or septic tanks. Reduced groundwater recharge and falling water tables impair natural filtration, while high temperatures accelerate decomposition, producing odors and discouraging use. Extreme events (such as flash floods following prolonged drought) further compromise systems, causing sewage discharge into water bodies and latrine overflow. These failures underscore the vulnerability of sanitation infrastructure to climate variability and its role in spreading waterborne diseases during severe scarcity or hydrological instability [137,162,163].

3.

Healthcare Facility Water Gaps

Inadequate water availability is a major challenge for healthcare facilities in low-resource settings, worsened by climate-related shortages. Many clinics and hospitals struggle to maintain reliable water for essential functions such as sterilization, safe deliveries, and infection prevention and control. During droughts or supply disruptions, facilities often ration water for sanitation, patient cleansing, and hand hygiene. These shortages, especially in remote facilities with limited infrastructure, compromise safety and increase risks of healthcare-associated infections, newborn sepsis, and adverse obstetric outcomes [31,164]. Facilities relying on tanker deliveries or private wells face added risks from poor water quality, as scarcity forces use of untreated sources. Power outages during heatwaves further disrupt pumps, storage, and treatment systems. In conflict-affected regions of MENA and Sub-Saharan Africa, some clinics have halted operations or depend on humanitarian agencies for emergency supply. These gaps weaken health system resilience and limit outbreak response. Strengthening water reliability in healthcare settings is a critical adaptation priority for climate-resilient public health systems [150,151,165].

4.3.3. Nutrition and Food Security

1.

Agricultural Decline and Crop Yield Reductions

Climate-driven water scarcity has sharply reduced agricultural output in fragile socio-ecological systems where smallholder and rain-fed farming remain central to food supply. Prolonged droughts and erratic monsoon rainfall have lowered yields of water-sensitive staples such as rice, wheat, and legumes in South Asia. Similarly, sorghum, maize, and millet production in Sub-Saharan Africa has declined due to reduced soil moisture, shorter growing seasons, and frequent droughts. In MENA’s arid zones, chronic water scarcity constrains irrigation, limiting cultivation of fruits, vegetables, and fodder crops essential for nutrition and livestock sustainability. Heat stress, declining river flows, and falling groundwater tables drive land abandonment, threatening local food sovereignty [166,167,168]. Scarcity also undermines traditional irrigation systems, increasing crop failures during unpredictable seasons. Reduced water availability for livestock worsens protein shortages by limiting milk and meat production. Smallholder farmers (especially women-led farms) face heightened vulnerability due to limited access to adaptation technologies such as drip irrigation, drought-resistant crops, and climate-smart agronomy. Ultimately, these constraints lower household food consumption, raise hunger risks, and increase reliance on imports or humanitarian aid, particularly in conflict-prone or economically fragile regions [70,81].

2.

Food Price Inflation and Dietary Shifts

Low-income households are highly vulnerable to food price inflation driven by water scarcity that reduces agricultural output. Staples such as rice, wheat, corn, and cooking oils become costlier due to lower yields and rising energy expenses for irrigation and groundwater pumping. Food prices are strongly linked to seasonal water availability in metropolitan areas of South Asia, Sub-Saharan Africa, and the MENA, peaking during droughts or irrigation shortfalls. These fluctuations strain household budgets, often forcing families to reduce meal frequency, prioritize cheaper calorie-dense foods, or eliminate nutrient-rich options like fruits, vegetables, meat, and dairy [89,168]. This shift accelerates a nutritional transition toward low-nutrient processed foods that are shelf-stable but less health-promoting. The quadruple burden of malnutrition, micronutrient deficiencies, and rising overweight and obesity intensifies. Price shocks also lower protein intake, hinder dietary diversity, and increase risks of anemia and stunting in children. Food insecurity linked to inflation contributes to family debt, migration, and market conflicts in fragile states, deepening climate-related stress [138,162,168].

3.

Impacts on Children and Pregnant Women

Due to their higher physiological demands and increased vulnerability to illness, children are particularly sensitive to the nutritional effects of water scarcity. Stunting, wasting, delayed cognitive development, and compromised immunological function are all consequences of ongoing food instability and recurrent exposure to waterborne illnesses. Diarrheal episodes become more frequent and severe in areas where water scarcity causes poor hygiene, which further restricts nutritional absorption and exacerbates malnutrition. These risks are exacerbated by seasonal hunger episodes, which frequently coincide with droughts or unsuccessful harvests. This leads to recurrent patterns of undernutrition that impact growth trajectories and long-term health effects. When clean water is unavailable, infants who rely on formula feeding are more vulnerable to tainted preparations [169,170]. Women who are pregnant or nursing face similar risks because food instability brought on by water scarcity restricts access to vital nutrients needed for both maternal and fetal health. Pregnant women are subjected to additional physiological strain due to decreased nutritional diversity and increasing water-collecting responsibilities, which increases the risk of low birthweight, stillbirth, anemia, and obstetric problems. In many low-resource environments, women may prioritize male family members or children above their own food intake during times of scarcity, which exacerbates health disparities. These combined pressures show how gendered and age-related inequities are reinforced by climate-driven water scarcity, endangering the development and health of future generations [169,170].

4.3.4. Mental Health and Psychosocial Impacts

1.

Stress and Anxiety from Water Scarcity

Climate-driven water scarcity imposes pervasive stress and anxiety on affected populations, stemming from uncertainty about reliable access to safe water for drinking, cooking, and sanitation. Households in South Asia, Sub-Saharan Africa, and the Middle East and North Africa frequently deal with sporadic supplies, lengthy collecting trips, and reliance on expensive or dangerous substitute sources, which can lead to long-term psychological stress. Sleep difficulties, irritability, and generalized anxiety can be made worse by people’s increased concern about fulfilling daily water demands, the safety of stored water, and possible pathogen exposure. In highly crowded metropolitan areas and refugee camps, where competition for limited resources exacerbates both individual and group stress, these mental health consequences are intensified [111,171]. In addition to causing anxiety at the family level, water scarcity erodes community perceptions of safety and social cohesiveness. Feelings of powerlessness and loss of agency are exacerbated by disagreements over water access, diminished community support systems, and uncertainty about seasonal supply. Research has shown that the psychological effects of water scarcity are frequently cumulative: recurrent exposure to droughts or supply disruptions strengthens chronic stress pathways, making people more susceptible to anxiety and depression. Water scarcity is a physiological and psychosocial risk due to the interaction between environmental stress and mental health [111,172].

2.

Farmer Suicides and Psychosocial Strain

Water scarcity in agricultural settings has been associated with greater psychological stress and, sadly, higher instances of farmer suicides in areas where crop failures occur often. Smallholder farmers in South Asia are at risk of experiencing significant psychological anguish due to cycles of debt, crop loss, and financial instability brought on by decreased monsoon predictability and groundwater depletion. Similarly, failing crops brought on by protracted droughts weaken livelihood security in Sub-Saharan Africa, leading to social marginalization, depression, and despair. Acute psychosocial pressure that can lead to self-harm is exacerbated by societal obligations to support extended families, cultural stigmas associated with requesting help, and restricted access to mental health care [173,174]. Persistent water-related agricultural stress causes rural people to experience chronic worry, exhaustion, and diminished coping skills in addition to suicide. Risky coping mechanisms that prolong financial and emotional stress include selling productive assets, moving under pressure, or taking out high-interest loans. Communities are affected by this emotional load, which weakens social cohesiveness and erodes confidence in regional organizations in charge of water management. The cumulative effect demonstrates a crucial feedback loop wherein water scarcity brought on by climate change exacerbates social vulnerability, mental health issues, and livelihood insecurity [174,175].

3.

Gendered Emotional Burdens

Culturally prescribed roles in household management, childcare, and water collection make women disproportionately vulnerable to the psychological impacts of climate-related water scarcity. In rural and peri-urban areas of South Asia, Sub-Saharan Africa, and the Middle East and North Africa, women often spend hours daily securing water, exposing them to physical strain, harassment, and heightened anxiety over family welfare. These responsibilities contribute to chronic stress, fatigue, and increased susceptibility to depression, particularly when compounded by food insecurity, childcare, and agricultural labor. Pregnant and nursing women face amplified risks due to combined physiological and emotional demands [176,177]. Gendered inequities further intensify emotional costs, as women and girls frequently manage inadequate supplies in households where men control water or financial resources. This imbalance not only causes daily stress but also limits education, social mobility, and empowerment, as time spent collecting water reduces opportunities for schooling and income generation. Collectively, these gender-specific mental health effects underscore the need for infrastructural and policy interventions alongside climate adaptation strategies that address the psychological dimensions of water scarcity [178,179].

4.3.5. Conflict, Displacement, and Social Instability

1.

Water-Based Conflict Hotspots

Climate-induced water scarcity has become a significant driver of both localized and transboundary conflicts, particularly in regions where resources are limited or shared across borders. Disputes over the Euphrates, Tigris, and Jordan basins in the Middle East and North Africa (MENA) illustrate how scarcity heightens competition between upstream and downstream states, often aggravating existing geopolitical tensions. In Sub-Saharan Africa, reduced river flows and shrinking reservoirs intensify clashes between pastoralist and agricultural groups over access to dwindling supplies. These conflicts carry psychosocial consequences, including heightened anxiety, stress, and trauma, especially when violence disrupts livelihoods [180,181]. At the local level, competition for seasonal rivers, irrigation canals, and communal wells can escalate into violence during prolonged droughts. Vulnerable populations, particularly children, face risks of displacement, restricted mobility, and social fragmentation, while households in conflict-prone areas experience chronic uncertainty. This interplay between conflict and water scarcity creates a feedback loop in which environmental stress amplifies social unrest, further limiting access to essential resources and worsening public and mental health vulnerabilities [182,183].

2.

Rural–Urban Migration and Public Health Strain

Water scarcity drives significant rural–urban migration as households seeks alternative livelihoods and more reliable water sources when local access or agricultural production becomes untenable. Growing numbers of climate migrants are moving to cities in South Asia, Sub-Saharan Africa, and MENA, placing heavy strain on urban water systems, sanitation facilities, and healthcare services. Rapid population influx often results in overcrowded informal settlements with poor access to clean water, inadequate hygiene, and heightened infectious disease risks, creating serious public health challenges [12,183]. Migrants also face increased psychological stress due to substandard living conditions, loss of social support networks, and economic insecurity. Overcrowding and insufficient water supplies make children and the elderly particularly vulnerable to waterborne illnesses, malnutrition, and mental health strain. This dynamic creates a dual burden: urban institutions struggle to maintain service quality, while migrants face elevated health risks. These trends underscore the urgent need for water resource management and climate-sensitive urban planning that account for migration patterns driven by water scarcity [9,33].

3.

Implications for Humanitarian Health Systems

Humanitarian health systems face mounting challenges in addressing interconnected crises of water scarcity, disease outbreaks, and displacement in regions affected by severe shortages. Organizations operating in drought-prone areas of South Asia, MENA, and Sub-Saharan Africa contend with unreliable water supplies, complicating emergency care, immunization campaigns, and hygiene promotion. Inadequate access to clean water in camps and informal settlements not only fosters vector-borne and diarrheal diseases but also heightens psychological stress among displaced populations and aid workers in resource-limited settings [11,137]. These pressures underscore the need for adaptive strategies integrating public health interventions with water resource management. During droughts and heatwaves, climate-resilient infrastructure, decentralized sanitation, and portable treatment systems are critical for sustaining essential services. Psychosocial support programs for displaced individuals, caregivers, and frontline personnel are equally vital to mitigate mental health burdens linked to prolonged scarcity and uncertainty. Collectively, these measures highlight the interdependence of water security, humanitarian resilience, and public health under climate-driven stress [184,185].

4.4. Gender and Equity Dimensions

4.4.1. Disproportionate Impact on Women and Girls

Entrenched social norms and gendered roles in household water management make women and girls disproportionately affected by climate-driven water scarcity. In South Asia, Sub-Saharan Africa, and MENA, women typically secure water for drinking, cooking, hygiene, and livestock. During shortages, these tasks become more time-consuming, physically demanding, and psychologically stressful, limiting opportunities for education, income generation, and social participation. Girls are often withdrawn from school to assist with collection, while persistent water scarcity heightens stress, fatigue, and vulnerability to mental health disorders [14,15,92]. Health impacts are significant: reliance on scarce water compromises childcare, sanitation, food preparation, and menstrual hygiene, increasing pathogen exposure. Pregnant and nursing women face added nutritional and hydration challenges, as scarcity restricts food preparation and fluid intake essential for maternal and fetal health. These dynamics underscore gendered vulnerabilities sustained by water scarcity and highlight the urgent need for targeted interventions to reduce disparities in access and health outcomes [92].

4.4.2. Gender Roles in Water Collection and Household Management

Cultural norms and family structures that assign women and girls primary responsibility for water collection, storage, and household management reinforce inequities in exposure to climate-driven shortages. In many rural and peri-urban areas, this role requires daily trips to distant sources (often several kilometers) while carrying heavy loads, imposing significant physical strain. These obligations restrict women’s participation in formal employment, education, and community decision-making, perpetuating cycles of socioeconomic disadvantage. Water scarcity further intensifies these burdens by increasing collection frequency, extending wait times at public taps, and heightening competition for limited supplies [9,92]. As women oversee childcare, food safety, and sanitation, the gendered division of labor directly influences household health outcomes. Scarcity forces prioritization of needs, often compromising hygiene or limiting water for vulnerable family members. In contexts where men dominate water governance, women frequently lack authority to implement conservation or allocation strategies, exacerbating risks. These systemic inequities underscore the need to integrate gender perspectives into water governance and climate adaptation policies [12,15].

4.4.3. Exposure to Violence and Safety Risks

Women and girls face heightened vulnerability to gender-based violence and physical harm during water scarcity, particularly when collection requires long-distance travel. Extended journeys increase exposure to theft, harassment, and assault, especially in remote or conflict-affected areas. Evidence from surveys and qualitative studies links drought-related competition for limited water resources to elevated risks of violence in regions such as Sub-Saharan Africa and South Asia [71,186,187]. These safety threats compound the psychological impacts of scarcity, contributing to chronic anxiety, fear, and social withdrawal. Beyond physical harm, water scarcity restricts women’s mobility and public participation. To reduce perceived risks, women often limit market or employment activities, while households may curtail girls’ movement, increasing school absenteeism and dropout. Such constraints undermine social and economic mobility and reinforce gender inequality, deepening vulnerability within water-stressed socio-ecological systems. Addressing these challenges requires integrated interventions combining improved water infrastructure, reliable access to safe drinking water, and community-based prevention strategies [188].

4.4.4. Equity Gaps in Water Access and Health Outcomes

Water scarcity disproportionately impacts marginalized populations (particularly women, girls, and low-income households), intensifying existing inequities in access and health outcomes. In urban informal settlements, irregular supply, inadequate sanitation, and poor storage compel reliance on unsafe sources, heightening exposure to vector-borne and diarrheal diseases. In rural areas, unequal distribution of residential and irrigation water privileges wealthier or male-headed households, leaving women and poorer families with insufficient and often contaminated supplies. These disparities directly influence disease burden, nutritional status, and resilience to climate stressors [189]. Health consequences reflect the compounded effects of scarcity and socioeconomic inequality: maternal–child health issues, malnutrition, and gastrointestinal disorders are prevalent among households lacking clean water. Children in such settings experience stunting and developmental delays, while women (disproportionately responsible for water collection and caregiving) face elevated risks of dehydration, fatigue, and waterborne illness. The intersection of gender, socioeconomic status, and climate vulnerability underscores the need for inclusive, equity-focused water and health interventions [92,190].

4.4.5. Social Justice and Rights-Based Approaches

Rights-based and social justice approaches emphasizing accountability, transparency, and inclusive participation in water governance are essential to address gendered disparities in access. Recognizing clean and sufficient water as a human right provides a framework for policies and infrastructure that ensure women and marginalized groups are not excluded. Rights-based strategies promote women’s involvement in planning, monitoring, and decision-making, fostering equitable distribution and ownership of climate adaptation initiatives [191,192]. Social justice frameworks further prioritize fair resource allocation and dismantling structural barriers that heighten vulnerability. Interventions such as gender-sensitive distribution policies, community-led management, safe collection points, and financial support for affected households can reduce physical and psychological burdens. Embedding equity, justice, and rights within climate-driven water management strengthens resilience, protects health, and ensures adaptation strategies target the most vulnerable rather than reinforcing existing inequalities [9,190].

4.5. Regional Case Studies

The case studies were selected because they represent diverse climate–water–health stress profiles across South Asia, Sub-Saharan Africa, and the MENA region, and because each country or subregion exemplifies a distinct pathway within the conceptual framework. India illustrates the pathway linking monsoon variability, groundwater depletion, and waterborne disease risk. Bangladesh highlights the interaction between riverine flooding, water contamination, and diarrheal disease outcomes. Ethiopia demonstrates the drought–food insecurity–malnutrition pathway. The Sahel region represents the compounded effects of chronic aridity, conflict-driven vulnerability, and health stress. Yemen exemplifies the governance–insecurity–water system collapse pathway leading to severe cholera outbreaks. Together, these cases were chosen to reflect the major climate–water–health pathways outlined in the conceptual framework and to provide regionally grounded illustrations of how these pathways operate in practice.

4.5.1. India: Intermittent Urban Water Supply and Public Health

Urban water scarcity in India constitutes a major public health concern, particularly in rapidly growing metropolitan areas such as Delhi, Mumbai, and Bangalore, where piped supply is increasingly intermittent. Municipal systems often function on rotational schedules, delivering water for only a few hours every few days. In India, recent serological and epidemiological analyses show that 11.7% of the sampled population carried elevated cholera vibriocidal antibodies, indicating significant transmission risk, with 29,400 reported cases between 2015 and 2019 [193]. This irregularity forces households to store water in rooftop tanks and containers, which frequently serve as breeding sites for pathogens and vectors like Aedes aegypti, thereby increasing risks of diarrheal and vector-borne diseases. In informal settlements, limited access to safe water further aggravates hygiene deficiencies and susceptibility to cholera, typhoid, and other enteric infections [9,193,194]. Beyond infectious disease, intermittent supply imposes significant social burdens: women and girls often spend extended periods collecting water, leading to physical strain, psychological stress, and reduced educational and economic opportunities. Children in water-stressed households face heightened risks of malnutrition and stunting due to poor hygiene and water quality. Persistent structural constraints (including weak institutional capacity, ineffective governance, and rapid urbanization) continue to hinder equitable access, although municipal measures such as leak reduction, improved storage, and decentralized treatment remain critical for mitigating health risks [195,196,197].

4.5.2. Ethiopia: Drought Cycles and Child Malnutrition

Recurrent droughts driven by climatic variability in Ethiopia have severe implications for public health and child nutrition, particularly in the Rift Valley and lowlands. In Ethiopia, the humanitarian situation includes 4.5 million people displaced as of 2023 due to drought, conflict, and flooding, conditions that contribute directly to increased disease vulnerability and malnutrition [198]. Water scarcity reduces agricultural yields and livestock production, undermining food security and increasing dependence on emergency aid. Prolonged dry spills, erratic rainfall, and high evapotranspiration exacerbate chronic malnutrition among children under five, leading to higher rates of stunting, wasting, and micronutrient deficiencies. Reliance on unprotected rivers, ponds, and shallow wells during droughts also elevates waterborne disease prevalence [199,200,201]. Health outcomes worsen as water scarcity disrupts sanitation services, limits access to clean water, and compromises hygiene in healthcare facilities. Malnourished children are particularly susceptible to infections, creating a cycle of illness and undernutrition. Adaptive strategies (such as rainwater harvesting, drought-tolerant crops, and integrated nutrition–water–hygiene programs) are critical to reducing child vulnerability and strengthening resilience against climate-driven water scarcity [201,202].

4.5.3. Yemen: Conflict, Water Collapse, and Cholera Epidemics

Yemen is a prime example of how long-term war and water scarcity combine to produce serious public health emergencies. Millions of people now lack consistent access to clean drinking water due to the collapse of water infrastructure, which is made worse by drought and excessive groundwater exploitation. In Yemen, the WHO reports that the country now bears the highest cholera burden globally, with 250,000 suspected cases and 861 deaths recorded by December 2024, accounting for 35% of global cases and 18% of global cholera deaths that year [203]. Yemen has one of the worst continuing cholera epidemics in the world due to contaminated water sources and inadequate sanitation and hygiene measures. Exposure risks are increased by the large density of displaced people in conflict-affected areas, and prompt diagnosis, treatment, and immunization are limited by the interruption of healthcare services [204,205]. The effects on society and psychology are likewise significant. Communities face ongoing stress, food shortages, and dislocation, all of which exacerbate mental health issues. Due to their higher exposure to polluted sources and the burden of water collection, women and children are disproportionately impacted. To reduce immediate dangers, humanitarian initiatives like emergency water trucking, drinking water purification, and cholera vaccine programs are crucial. However, systemic breakdown and continuous violence impede long-term water security and lasting gains in public health [83,89].

4.5.4. Bangladesh: Climate-Driven Salinity and Maternal Health

Rising sea levels, storm surges, and tidal intrusion have increased salinity in surface and groundwater across coastal Bangladesh, with serious implications for maternal health, drinking water safety, and agriculture. In Bangladesh, cholera remains endemic, with the country consistently listed among those with the highest annual cholera burden globally, with an estimated annual Vibrio cholerae O1 infection incidence rate of 535 per 1000 population [206]. Communities relying on shallow tube wells face elevated salt intake, contributing to hypertension, preeclampsia, and other pregnancy-related complications. Salinity intrusion further limits freshwater for irrigation and domestic use, forcing dependence on brackish or unsafe sources. Women, primarily responsible for water collection, experience physical and psychological stress, negatively affecting prenatal care and child health [207,208]. Salinity-driven scarcity also reduces crop yields, restricts nutrient access, and increases reliance on processed foods lacking micronutrients, heightening risks of anemia and malnutrition among pregnant and lactating women. While adaptation measures (such as rainwater harvesting, small-scale desalination, and salt-tolerant crops) are being piloted, implementation remains limited, underscoring the complex interplay between environmental change, gendered vulnerability, and public health [208].

4.5.5. Sahel Region: Water Conflict and Displacement

The Sahel region of Sub-Saharan Africa illustrates how sociopolitical conflict and climate-induced water scarcity converge to shape public health outcomes. In the Sahel, the scale of drought-driven food insecurity is severe, with 45,000 people experiencing catastrophic hunger in 2023, including 42,000 in Burkina Faso and 2500 in Mali. Humanitarian assessments also report that nearly 33 million people across the broader Sahel (Burkina Faso, Cameroon’s Far North, Mali, Niger, northeastern Nigeria, and Chad) require assistance, with 5.7 million internally displaced and 2 million refugees as of late 2024. These conditions heighten vulnerability to infectious diseases, reflected in the fact that the WHO African Region—which includes the Sahel—reported 17 countries affected by cholera outbreaks in 2023, contributing significantly to the 684 outbreaks recorded in the region between 2000 and 2023 [23,209]. Recurrent droughts and declining water availability intensify competition between pastoralist and agricultural groups, triggering localized disputes over rivers, wells, and irrigation systems. These conflicts frequently displace communities to informal settlements or refugee camps with inadequate water, sanitation, and healthcare infrastructure. In such settings, women and children face heightened risks of psychological stress, hunger, and waterborne diseases [11]. Displacement further strains local health systems, which struggle to provide immunization, nutrition, and hygiene for temporary populations. High population density and limited access to safe drinking water accelerate the spread of diarrheal and other infectious diseases. Mitigating these compounded risks requires integrated humanitarian strategies combining public health interventions, conflict resolution, and water resource management. This case underscores how socio-political and environmental dynamics intersect with climate-driven water scarcity to produce severe public health challenges [12,151].

5. Discussion

5.1. Synthesis of Cross-Regional Patterns

A multi-regional analysis reveals common patterns in the public health impacts of climate-driven water scarcity across South Asia, Sub-Saharan Africa, and MENA. Declining surface and groundwater resources and deteriorating water quality consistently contribute to malnutrition, psychological stress, and waterborne disease transmission. Urban areas face heightened vulnerability due to dense populations and intermittent supply, while rural communities experience compounded risks from agricultural dependence and limited access. Women and girls bear disproportionate burdens related to household hygiene and water collection, increasing physical, emotional, and social stress [150,151,154]. Regional variations reflect hydroclimatic and sociopolitical contexts: Bangladesh struggles with chronic saltwater intrusion affecting maternal health, Yemen and the Sahel endure conflict-driven scarcity with elevated disease and displacement risks, and informal settlements in South Asia face intensified exposure from groundwater depletion and unreliable municipal supply. These findings highlight universal mechanisms alongside context-specific stressors, underscoring the need for broad resilience strategies complemented by targeted interventions [4,204,208,210].

5.2. Multipathway Public Health Risk Model

Water scarcity affects public health through several interconnected channels, such as direct consumption of tainted water, poor sanitation and hygiene, dietary deficiencies, and psychological stress. Beyond the impact of individual processes, the convergence of these channels produces cumulative and frequently synergistic effects that increase the risk of illness. For example, not having enough water to wash your hands increases the spread of pathogens, which exacerbate diarrheal disease morbidity and mortality when combined with hunger from lower agricultural output. Stress, worry, and sadness are among the mental health consequences that result from the physical strain of collecting water as well as from the general socioeconomic instability associated with shortage [9,61]. The temporal dynamics of risk are further highlighted by this multipath view, where chronic shortages lead to long-term health deficiencies including stunting, anemia, and mental health issues, while acute scarcity events cause sudden disease epidemics. The identification of high-priority interventions, such as focused water supply improvements, hygiene promotion, nutrition support, and psychological care, is made easier by integrating these pathways into a coherent risk model. Policymakers may create comprehensive plans that reduce cascading public health consequences among vulnerable communities by acknowledging the interdependencies among water, nutrition, illness, and mental health [174,184].

5.3. Governance as a Determinant of Water and Health Outcomes

Governance quality is a critical determinant of public health outcomes under climate-driven water scarcity. Regions such as Israel and parts of the United Arab Emirates exhibit resilience to drought and supply disruptions through robust regulatory frameworks, transparent allocation policies, and effective infrastructure maintenance. Conversely, weak governance in Yemen, Sudan, and parts of South Asia (characterized by fragmented institutions and corruption) exacerbates shortages, resulting in inequitable distribution, infrastructure deterioration, and public health crises. These failures disproportionately affect marginalized populations, including low-income households, women, and children [89]. Effective governance requires disaster preparedness, intersectoral coordination, and adaptive planning that integrates climate forecasts into water management. Cross-border water conflicts, lax enforcement of extraction limits, and limited community engagement create systemic vulnerabilities to infectious and chronic health risks. Strengthening institutional capacity, promoting participatory governance, and aligning policies with climate adaptation frameworks are essential to ensure equitable access to safe water and mitigate health burdens [174,181].

5.4. Intersections of Climate, Water Security, and Socio-Economic Inequality

Socio-economic inequality intensifies the health impacts of climate-driven water scarcity by shaping exposure, sensitivity, and adaptive capacity. Wealthier households can offset scarcity through storage, alternative sources, or purchasing safe water, while low-income and marginalized groups remain vulnerable to unsafe or insufficient supplies. Droughts and erratic rainfall disproportionately affect those with limited financial, social, or political capital, worsening disease burden, malnutrition, and psychological stress [89]. Gender and age further compound these disparities, as women, girls, and children face heightened vulnerability due to culturally assigned roles in caregiving and water collection. Intersectional research confirms that water scarcity is not a uniform stressor; its health effects vary by social, economic, and demographic factors. Adaptation strategies must therefore address structural barriers, gendered responsibilities, and household-level vulnerabilities [91,138].

5.5. The Role of Technology and Innovation

Technological innovations play a critical role in mitigating public health risks associated with water scarcity. Tools such as smart water metering, satellite monitoring, IoT sensors, and precision irrigation enable efficient allocation, real-time water quality tracking, and early detection of shortages or contamination. In agriculture, drought-tolerant crops and optimized irrigation schedules reduce food insecurity and related health impacts. Decentralized treatment systems and leak detection improve supply reliability and lower exposure to waterborne diseases in urban areas [11,45]. However, technology alone cannot overcome social and structural barriers. Access remains unequal, with rural and low-income communities benefiting least from advanced systems. To ensure equitable health outcomes, technological solutions must be complemented by policies that integrate community participation, education, and governance reforms. Combining innovation with adaptive management and inclusive frameworks strengthens resilience to both short-term shortages and long-term health challenges driven by climate change [89].

5.6. Unanswered Questions and Research Gaps

Despite growing evidence of climate-driven water scarcity and its health impacts, significant knowledge gaps remain. Limited longitudinal data constrains understanding of chronic outcomes such as stunting, mental health effects, and intergenerational repercussions. Similarly, linkages between water scarcity, food security, and emerging infectious diseases beyond traditional waterborne pathogens are poorly documented. Regional disparities in data availability (especially in remote or conflict-affected areas) further hinder risk prediction and context-specific interventions. Future research must address multi-scalar dynamics by integrating hydroclimatic forecasts with socioeconomic, governance, and health data. Evaluating the effectiveness of technical, regulatory, and behavioral adaptation strategies is also critical. Studies focusing on age- and gender-specific vulnerabilities, equity considerations, and psychological dimensions of scarcity will enable more targeted solutions. Closing these gaps is essential for evidence-based policies that mitigate the complex health consequences of climate-related water scarcity.

5.7. Policy and Practice Recommendations

Figure 6 visually organizes all nine policy domains around the central Integrated Policy Framework, and they are all described in this section.

5.7.1. Strengthening Water Governance and Regulatory Systems

Effective and equitable water management under climate-driven scarcity requires robust governance and regulatory frameworks. Policies that establish clear allocation priorities, limit extraction, and enforce water quality standards can mitigate both acute and chronic public health risks. In contexts complicated by informal settlements, agricultural competition, and transboundary disputes, strengthening institutional capacity, accountability, and transparency is critical. Adaptive management approaches enable governments to adjust distribution and enforcement in response to evolving climate conditions and community needs [9,94]. Multi-level coordination among local, national, and regional authorities, coupled with civil society and community participation, promotes equitable resource distribution, trust, and compliance. Ensuring representation of vulnerable groups (such as women, children, and low-income households) in decision-making processes safeguards access to clean water and associated health outcomes. Governance reforms that integrate institutional strength with participatory approaches are essential to reducing the public health burden of water scarcity [147,188].

5.7.2. Climate-Resilient WASH Infrastructure Investment

Investment in climate-resilient water, sanitation, and hygiene (WASH) infrastructure is imperative for safeguarding public health under conditions of increasing water scarcity. Infrastructure upgrades (such as expanded piped networks, reinforced storage systems, and drought- and flood-resistant treatment facilities) enhance reliability during extreme climatic events. Incorporating redundancy and modularity within WASH systems ensures service continuity under stress, thereby reducing disease outbreaks and hygiene-related health risks [9,10]. Infrastructure deficits are most pronounced in rural and peri-urban areas, necessitating targeted interventions including well rehabilitation, improved access to potable water, and upgraded sanitation facilities to mitigate urban–rural health disparities. Long-term sustainability requires coupling physical improvements with capacity building for local maintenance. Furthermore, these investments reduce time and labor burdens associated with water collection (particularly for women and children) while promoting socioeconomic stability and public health outcomes [12,14].

5.7.3. Integrated Climate–Water–Health Surveillance Systems

Integrated monitoring systems that link hydrological, climatic, and public health data can significantly improve early warning and response to water-related health risks. Real-time tracking of temperature, rainfall, river flow, groundwater levels, and water quality (combined with disease incidence) enables prediction of cholera, diarrheal diseases, and other waterborne outbreaks. Such systems support proactive measures like targeted vaccination, emergency water supply, and hygiene campaigns, rather than reactive responses after illness peaks [107,115]. Integration also strengthens evidence-based policy and resource allocation by identifying vulnerable areas. Combining digital monitoring with community reporting enhances data granularity, particularly in remote or informal settlements. Ultimately, integrated surveillance improves adaptive capacity, reduces health impacts, and optimizes resource use in water-stressed regions by providing actionable insights on emerging threats [9,113].

5.7.4. Community-Based Water Safety Planning

Community-based water safety planning fosters resilience and public health by enabling local communities to address hazards related to water scarcity and pollution. Local actors take charge of water safety by integrating homes, schools, and community organizations in risk assessment, water quality monitoring, and mitigation strategies. This strategy improves compliance, raises understanding of sanitation and hygiene practices, and lowers exposure to pathogens, especially in situations with informal water systems or poor centralized control [9,116]. Additionally, these strategies promote adaptive management that takes into consideration climate extremes and seasonal variations. Rainwater collection, home filtration, and safe storage techniques are examples of community-led initiatives that can protect homes from sporadic supply or transient contamination. A multi-layered approach that safeguards health and increases local ability to address current and future water scarcity issues is created when community water safety planning is linked with municipal or regional authorities. This ensures alignment with larger infrastructure and policy projects [152,156].

5.7.5. Gender-Responsive Adaptation Strategies

Gender-responsive adaptation is essential to address the disproportionate impact of water scarcity on women and girls and to strengthen resilience. Policies that prioritize safe water access, reduce collection burdens, and promote equitable participation in water governance enable women to devote more time to education, employment, and caregiving. Targeted interventions (such as supporting female-led water management, improving menstrual hygiene facilities, and ensuring clean water near households) directly mitigate gendered vulnerabilities [14,92]. Incorporating gender analysis into climate adaptation enhances public health outcomes by aligning interventions with real needs, as women often serve as primary caregivers and household health managers. Empowering women in water allocation, sanitation, and hygiene promotion fosters lasting behavioral change, improved family hygiene, and better nutrition, demonstrating the combined benefits of gender-sensitive strategies for equity and health [188].

5.7.6. Promoting Climate-Resilient Agriculture

Adaptation of agriculture to climate-induced water scarcity is essential for mitigating food insecurity and associated public health risks. Strategies such as crop diversification, precision irrigation, drought-tolerant cultivars, and soil moisture conservation enhance resilience to erratic rainfall and declining groundwater resources. These interventions are particularly critical for rural populations dependent on subsistence farming, as they help prevent child malnutrition, anemia, and protein deficiencies linked to reduced yields [69,75]. Climate-resilient practices also advance broader water management objectives by improving efficiency and curbing groundwater over-extraction. Integrating agroecological principles with indigenous knowledge sustains soil fertility and ecosystem services, ensuring long-term sustainability. Furthermore, aligning agricultural adaptation with nutrition and public health programs fosters synergies between water security, food systems, and health outcomes, particularly in resource-constrained and high-risk regions [167].

5.7.7. Cross-Border Water Diplomacy and Conflict Prevention

In MENA and the Sahel, where rivers and aquifers span national borders, transboundary water management is crucial for lowering conflict and fostering regional stability. Competition-driven disputes can be avoided by diplomatic processes that create cooperative water-sharing agreements, collaborative monitoring, and dispute resolution frameworks. These programs immediately improve public health by providing a steady supply of water for communities, agriculture, and sanitation by guaranteeing predictable access to shared resources [9]. Coordinated responses to droughts, severe events, and climatic variability are also made possible by cross-border cooperation. Knowledge sharing, common infrastructure investments, and regional early warning systems increase group resilience and lessen susceptibility to both acute and long-term public health issues. Thus, enhancing cooperative governance and diplomacy tackles socio-political risks as well as health outcomes, highlighting the vital connection between public health, peace, and water security [9].

5.7.8. Digital Tools for Water Monitoring and Health Risk Forecasting

In the context of climate-driven scarcity, digital technologies offer significant potential to improve public health and water management. Real-time monitoring of supply, quality, and consumption is enabled by satellite imaging, remote sensing, IoT sensors, and mobile apps. Combining these data with health systems supports predictive modelling of disease outbreaks, aiding resource allocation and targeted interventions before crises escalate [37,40]. Digital tools also enhance transparency, capacity building, and community engagement in water governance. Mobile reporting platforms allow households to report interruptions or contamination, strengthening regional early warning systems. Data-driven decisions boost efficiency, reduce waste, and build climate resilience. When paired with participatory planning and gender-sensitive strategies, digital innovation becomes a powerful tool to mitigate public health risks, promote equity, and improve water management across diverse socio-ecological contexts [37,40].

5.7.9. Policy Implications and Region-Specific Interventions

The findings of this study have direct implications for region-specific policy formulation and intervention strategies across South Asia, Sub-Saharan Africa, and the Middle East and North Africa (MENA), where climate-driven water scarcity poses escalating public health risks.

In South Asia, where water availability is strongly influenced by monsoon variability and glacier-fed river systems, the results underscore the need for strengthened integrated water resources management (IWRM) and climate-resilient water infrastructure. Policies should prioritize groundwater regulation, sustainable irrigation practices, and expansion of climate-resilient drinking water supply systems. Public health interventions should focus on strengthening WASH services, early-warning systems for drought and heat stress, and nutrition-sensitive water policies to mitigate the health impacts of water scarcity among vulnerable populations.

In Sub-Saharan Africa, characterized by high climate variability, recurrent droughts, and limited water infrastructure, the findings highlight the urgency of enhancing adaptive capacity through decentralized water supply systems, climate-smart agriculture, and ecosystem-based water management. Policy interventions should target improved governance of surface and groundwater resources, investment in rural and peri-urban water infrastructure, and integration of climate adaptation into national health and development plans. Strengthening community-based water management institutions and gender-inclusive water governance frameworks is critical for reducing inequitable health outcomes.

In the MENA region, where arid and semi-arid climatic conditions dominate and water scarcity is structurally entrenched, the study’s results support the expansion of non-conventional water resources, including desalination, wastewater reuse, and managed aquifer recharge. Policy measures should emphasize demand-side management, water pricing reforms, and cross-sectoral coordination between water, energy, and health sectors. Public health interventions should focus on ensuring equitable access to safe water, strengthening surveillance of water-related diseases, and addressing the compounded health risks associated with heat stress and water scarcity.

Across all regions, the findings emphasize the need for integrated climate–water–health policy frameworks, improved data sharing between water and health sectors, and targeted investments in vulnerable communities. Strengthening institutional coordination, climate financing mechanisms, and community-level resilience strategies will be essential to mitigate the cascading impacts of climate-driven water scarcity on public health.

6. Conclusions

Vulnerable communities in South Asia, Sub-Saharan Africa, and MENA face severe climate-driven water scarcity, creating complex public health challenges. Declining water supplies, poor quality, and weak infrastructure drive widespread risks, as shown by this multi-regional analysis of shared and region-specific patterns. Acute events such as droughts, conflicts, and saline intrusion worsen impacts, while waterborne diseases, malnutrition, mental stress, and gender disparities persist. Case studies reveal that climate, inequality, governance, and technical capacity shape outcomes, emphasizing the need for integrated approaches linking environment, society, and health. Interactions among water access, sanitation, nutrition, and mental health show that single-sector solutions are inadequate. Age and gender vulnerabilities require targeted strategies to strengthen resilience and equity. While technology and digital monitoring offer promises for forecasting and resource management, strong governance, infrastructure, and regional cooperation remain critical. Policy priorities include multi-level action, investment in climate-resilient WASH systems, climate-smart farming, gender-responsive programs, and water governance. Digital monitoring and cross-border water diplomacy can enhance security, while community-based planning and integrated surveillance improve early warning and disease control. Policies must reflect local hydroclimatic, sociopolitical, and demographic realities to ensure equitable access and long-term health.

This study identifies key research gaps, notably the lack of longitudinal data on intergenerational health effects, mental health outcomes, and chronic disease burdens, particularly in conflict-affected and resource-constrained settings. Further inquiry is needed into adaptation efficacy, linkages among infectious disease, nutrition, and water scarcity, and integration of gender-sensitive frameworks into policy and practice. Addressing these gaps will enable evidence-based, multi-sectoral interventions that strengthen resilience and mitigate health risks. In sum, climate-related water scarcity constitutes a multidimensional public health challenge rooted in social, economic, and governance dynamics rather than solely environmental or infrastructural deficiencies. Effective responses demand coordinated, cross-sectoral strategies informed by rigorous research and guided by principles of equity, gender inclusion, and human rights. Integrating climate adaptation, public health preparedness, and community engagement will be essential to safeguarding vulnerable populations, reducing disparities, and fostering resilient socio-ecological systems capable of withstanding escalating water scarcity pressures.