Towards Integrated Water–Energy Systems in Mountain Environments: Insights from a Systematic Literature Review

Abstract

Mountain regions are increasingly affected by the interplay of climate change, infrastructure stress, and evolving socio-ecological systems, intensifying pressure on both water and energy systems. This systematic review investigates how recent scientific literature addresses the management and integration of water and energy systems in mountainous contexts. Following PRISMA guidelines, 88 peer-reviewed studies from 2022 to 2025 were selected through structured database queries and thematic screening. Two key imbalances emerge. First, a geographical imbalance is evident: while the majority of studies come from Asia, Europe shows a strong record of applied efforts, the Americas are moderately represented, and research from Africa remains scarce. Second, a thematic imbalance: water management research is conceptually and methodologically mature, while energy-focused studies remain limited in number and scope. Efforts toward integrated water–energy management are emerging but are mostly confined to pilot projects or modelling exercises, often lacking systemic framing and institutional support. From these findings, three priority directions are identified: advancing adaptive co-design approaches that link water supply, energy storage, ecological flows, and human demand; harmonizing methods, metrics and cross-regional benchmarks to enhance comparability and transferability; strengthening social and institutional pathways to foster resilient, adaptive water–energy systems in mountain environments.

1. Introduction

Estimates of the global extent of mountain ecosystems vary considerably, ranging from about 12.3% to 30.4% of the Earth’s terrestrial surface, largely depending on the definitions and methodological approaches adopted. In this regard, a recent assessment placed the coverage at 12.5% [1]; a global inventory provided values of 12.28% and 18.21% under the GMBA v1 and v2, respectively, 24.23% according to UNEP-WCMC, and as high as 30.38% based on USGS criteria [2]; complementing these values, the IPCC Sixth Assessment Report suggested an intermediate estimate of 23.5% [3]. In parallel, the global population residing in mountain areas is estimated to range from 5% to 31% [4], around 17% according to the IPCC [3], and around 20%, as reported by a global review published in 2024 [1]. Overall, regardless of the choice of data, substantial human populations are likely to be directly affected by environmental and ecological changes in mountain areas, while at the same time contributing to shaping them [4].

In this context, future changes in mountain populations worldwide are expected to be influenced by the climate change mitigation and adaptation strategies chosen [3], described and presented by the IPCC in five separate scenarios called Shared Socioeconomic Pathways (SSPs), through which the possible future population dynamics of mountain areas are explained. By 2100, the population in mountains will reach about 1100 million people under SSP1 (Sustainability) and SSP5 (Fossil-fuelled Development), approximately 1550 million under SSP2 (Middle of the Road), about 1700 million under SSP4 (Inequality) and almost 2350 million under SSP3 (Regional Rivalry) [3]. These projections underscore the extent to which different socio-economic trajectories may influence demographic dynamics in mountain regions, highlighting the need for context-specific management strategies to address the resulting environmental and socio-economic challenges. As a result, flexible resource management systems will be required, capable of adapting to fluctuations in the supply and demand of natural resources, in accordance with environmental availability, which will inevitably be affected by climate change.

By the mid-21st century, under a moderate development scenario, it is projected that approximately 1.5 billion people, representing around 24% of the global lowland population, will critically rely on runoff originating from mountain regions. This marks a substantial rise from the 1960s, when only about 200 million people (7%) were similarly dependent. The primary driver of this increase is the intensification of water consumption in lowland areas, rather than significant changes in runoff patterns [5].

The cryosphere functions as the most significant environmental factor that determines future water supply in mountain areas, sustaining both highland ecosystems and downstream population centres. Mountain glaciers and snowpacks serve as vital freshwater sources that supply nearly half of the world’s population [6,7,8] and function as key regulators of local weather and water patterns in the surrounding areas. The rapid shrinkage of mountain cryosphere continues to accelerate as a consequence of global warming, which causes destabilization of these sensitive systems that produces widespread effects on biodiversity, water security, and socio-economic stability throughout connected territories [6]. A review focused on the European Alps highlights that projected warmer winters and reduced snow cover are expected to shift both the timing and magnitude of surface runoff, with significant implications for socio-economic sectors such as tourism, agriculture, and hydropower [9].

As mountain areas confront mounting challenges associated with climate change and resource accessibility, renewable energy transition is revealed as a central strategy for building resilience. The use of locally available resources can dramatically enhance the energy autonomy of the territories while reinforcing environmental viability and territorial development [10]. Those territories, despite infrastructural limits, present high aptness for decentralized renewable energy deployment, thanks to their elevated endogenous resource potential [11]. Hydropower is one of the most extensively used renewable resources in mountainous regions [12], offering both stable energy and storage capacity. Yet, its reliance on climate-vulnerable water flows exposes local energy systems and populations to risks. To counterbalance these uncertainties, there is an increasing tendency to hybrid systems combining hydropower with wind and solar technologies and thus consolidating overall energy security [13].

This transition is further supported by the favourable climatic conditions of high-altitude regions, where both wind speeds and incident solar radiation tend to increase versus altitude [14,15]. In the broader context of the energy potential in mountain regions, two additional renewable sources, forest biomass [16] and biogas [12], also emerge as viable and used options.

However, technical solutions by themselves will be inadequate without robust institutional support together with local community engagement and widespread acceptance of new infrastructure in the region. To optimize the benefits of a diversified energy mix in these vulnerable areas, regional coordination and consistent economic policies must be established [13]. The intricate and interconnected nature of mountain systems is clearly evident: integrated smart energy and water management systems can play a key role in supporting the transition towards greater efficiency and sustainability in resource-constrained mountain areas [17].

Following these reflections, this review seeks to systematically assess the corpus of recent studies aimed at understanding and enhancing water and energy management in mountain regions, highlighting the principal approaches, challenges, and solutions suggested in the literature, with specific concern for the level of their integration and the way in which this integration is conceptualized in management models.

The analysis was restricted to publications from 2022 to 2025, as the focus of this review is on the most recent developments in the field. The decision to restrict the review to this temporal period aims to encompass studies that used the most recent methodological and technical advances, which is crucial to understanding the current research trends. The specific date range prevents inconsistencies from including older studies that had different underlying assumptions or methods. Finally, by narrowly focusing on recent publications, this study enables highlighting of findings with direct applicability to current management practices and policy decisions.

The paper is thus organized as follows: “Material and Methods” presents the methodology adopted in the study, i.e., how the review was planned, data extraction and the thematic analysis. Section 3 is devoted to presenting the results of the study, while the discussion examines the avenues of research. Finally, in the conclusions, we provide the main research gaps and highlight the future research agenda. The limitations of the study are also debated.

2. Materials and Methods

2.1. Planning the Review

The research strategy adopted for this review explains the methodological steps used and the reasoning behind each approach. The study focused special attention on source selection criteria to maintain analytical coherence and thematic relevance across all research activities. The review followed PRISMA statement guidelines [18] to achieve both methodological transparency and reproducibility during the review process. The chosen methodology established a systematic approach to identify and select pertinent literature, which enabled the development of a solid analytical framework. A properly organized literature review was fundamental to build an extensive and logical analysis. The main terms that stand out in this research domain focus on energy management, water management, energy–water nexus management and the implementation of integrated management systems in mountain regions.

To identify the relevant literature, systematic searches were conducted using Scopus and Web of Science. The queries were formulated using Boolean operators and thematic keywords related to integrated energy and water management in mountain contexts. The main search review prompt was as follows:

(WE nexus” OR “water-energy nexus” OR “water and energy management” OR “energy and water management” OR “energy management” OR “water management”) AND (system* OR “integrated system” OR “integrated systems”) AND (mountain* OR alp* OR alpine).

2.2. Parameters of the Study and Data Extraction

In accordance with the PRISMA statement, every methodological filter used to construct the set of analyzed papers is reported below, from the initial string search across both databases to the final number of studies included in the review, providing the PRISMA flow diagram at the bottom of this paragraph (Figure 1). The initial search query yielded 2146 results in Scopus and 1724 in Web of Science. As a first-level filter, only documents written in English were retained, excluding 132 and 22 records, respectively. Subsequently, the results were restricted to publications from 2022 to 2025, leading to the exclusion of 1430 documents from Scopus and 1181 from Web of Science. An additional selection step limited the corpus to articles and reviews only, and, considering the previous exclusion criteria, 520 documents remained in Scopus and 482 in Web of Science.

A thematic filter was then applied based on subject area (Scopus) and research area (Web of Science) to exclude records unrelated to the focus of the study and misaligned with the research question. In Scopus, the excluded subject areas included “Agricultural and Biological Sciences,” “Arts and Humanities,” “Biochemistry, Genetics and Molecular Biology”, “Chemical Engineering”, “Health Professions”, “Immunology and Microbiology”, “Materials Science”, “Mathematics”, “Medicine”, “Neuroscience”, “Nursing”, “Pharmacology, Toxicology and Pharmaceutics”, “Physics and Astronomy”, “Social Sciences”, “Chemistry”, and “Computer Science.” This refinement eliminated 194 additional documents, resulting in 274 items selected for the screening phase. In Web of Science, the inclusion criteria were defined as follows: “Water Resources”, “Environmental Sciences & Ecology”, “Engineering”, “Science & Technology—Other Topics”, “Meteorology & Atmospheric Sciences”, “Remote Sensing”, “Operations Research & Management Science”, “Automation & Control Systems”, “Instruments & Instrumentation”, and “Urban Studies.” The application of these filters excluded 136 documents, leaving 346 eligible studies.

By comparing the filtered results from both databases, 53 duplicates were identified. After their removal, the total number of unique documents deemed potentially relevant for the systematic review amounted to 567.

The reading of titles and abstracts led to the selection of 129 articles considered relevant to the context of our analysis. The selection criteria applied during the screening process were adapted to the size and scope of the retrieved results. The classification of the selected documents follows a division into three main categories: water management, energy management, and integrated water and energy management. These three dimensions were then subdivided, where possible, into subcategories reflecting different aspects and organized according to an estimated level of relevance to the research. This detailed classification enabled the adoption of distinct inclusion strategies for documents addressing water and energy management, while maintaining consistency with the overarching research question focused on mountain contexts. Specifically, all articles related to water management concern studies conducted exclusively in mountain areas or in regions where the mountain ecosystem exerts a significant influence. Similarly, although the initial screening phase for energy-related literature required a broader perspective due to the relative scarcity of studies explicitly addressing energy management in mountainous areas, the final selection was rigorously refined to include only those contributions directly situated in or explicitly referring to mountain environments. Documents whose applicability extended generically to other geographic contexts, without clear reference to mountain-specific dynamics or geolocated in non-mountainous areas, were excluded in order to ensure full alignment with the scope of the review.

During the full-text review phase, seven articles were excluded, as their complete versions could not be located in the consulted academic databases or through open-access sources. Of the remaining 122 documents retrieved for in-depth analysis, 24 were excluded as they did not pertain to mountain environments, either lacking any geographical specificity or focusing on contexts unrelated to the scope of this review. A further 10 studies were removed because they did not respond adequately to the research question and were therefore deemed irrelevant for the purposes of the analysis. As a result, the final number of publications included in the systematic review amounts to 88.

2.3. Thematic Analysis Methodology

A thematic analysis was conducted using the VOSviewer software (6.20 version). VOSviewer functions as a bibliometric mapping tool, created by Van Eck and Waltman at Leiden University [19] to perform structured analysis of selected scientific literature thematic patterns. VOSviewer software provides users with the capability to develop visual representations of bibliometric networks through analysis of co-authorship, keyword co-occurrence, citation pattern, bibliographic coupling, and co-citation [20]. This study used keyword co-occurrence analysis through the software to identify thematic clusters and fundamental research connections in the field.

Bibliographic data were exported in RIS format from Scopus and Web of Science and pre-processed to unify both RIS files to build a database map. The thesaurus file (viewable in the Supplementary Materials) was created to integrate different terms that represent the same concept (e.g., “climate-change” and “climate-change impacts” in “climate change”, “models” and “modelling” in “model”, “mountain regions” and “mountains” in “mountain”) and to eliminate geographical keywords (e.g., “china”, “california”, “tianshan mountains”, “tibetan plateau”), terms that do not add meaning to the thematic analysis but change the focus from a thematic to a geographical one. The co-occurrence analysis used author and indexed keywords as input with a minimum occurrence threshold of 2 to provide a clear and general visualization of the patterns. The size of nodes in the visualization, directly correlated with keyword text size, represents how often terms appear, while link distance and thickness show the strength of co-occurrence connections. The clustering method with built-in modularity functionality performed automatic colour assignment for detected clusters. The manual adjustments of attraction (=4) and repulsion (=2) settings improved readability without changing the original structural connections between elements.

3. Results

The temporal distribution of the publications (Figure 2) included in this review, covering the years 2022 to 2025, shows some variability. The highest number of studies was published in 2022 and 2024, while 2023 saw a noticeable decrease, with roughly half as many publications. The lower number of papers in 2025 is likely due to the fact that the year is still ongoing, and additional studies may yet be published.

Alongside the temporal distribution, the analysis of publication venues (Figure 3) reveals a fragmented landscape, with the reviewed literature spread across 45 different journals. Most of these journals contribute only one or two articles, indicating the absence of a single dominant outlet. The variety of journals from fields such as hydrology, environmental sciences, and sustainability reflects the interdisciplinary nature of the topic and further highlights the dispersed nature of the research dissemination. A few journals, however, stand out for their higher publication counts. “Journal of Hydrology” is by far the most represented, followed by “Remote Sensing”, “Hydrology and Earth System Sciences”, “Science of the Total Environment”, and “Water”.

The systematic review includes 88 studies, which are shown as a geographic distribution on Figure 4. The countries present on the map have been grouped into four major regions through color coding: Asia (red), Europe (green), the Americas (yellow), and Africa (orange). The colors on the map represent the regional affiliation of each country, but they do not show the number of studies performed in each nation. The legend shows the total research effort of each region through aggregate publication counts, which include 47 studies from Asia, 23 from Europe, 17 from the Americas and 1 from Africa. The map uses regional color coding to show country-level study distribution, and the legend provides numerical counts that display total research intensity for each region, helping readers quickly understand both spatial distribution and regional research levels. The research established guidelines to maintain classification consistency when dealing with transcontinental countries. Specifically, Turkey was included in the Asian group, as both studies linked to its territory focused exclusively on areas within Anatolia. Likewise, Kazakhstan was classified as part of Asia, as the study associated with its territory is set in a region located east of the Ural River, commonly regarded as the boundary between Europe and Asia.

Thematic Analysis

Firstly, a keyword co-occurrence analysis conducted through VOSviewer (Figure 5) identified a total of 110 keywords that were divided into nine different clusters automatically. The network consists of several highly interconnected keywords that hold the most substantial total link strength, demonstrating their importance across different thematic domains. The seven keywords that possess the greatest total link strength values include climate change (161), water management (97), precipitation (95), model (83), runoff (75), impact (67), and water (67). These keywords link multiple clusters, making them act as semantic bridges connecting different parts of the knowledge landscape.

Before a cluster analysis, it is evident that water-related thematic keywords emerge as the predominant group when looking at the entire map (Figure 5). Each cluster (viewable graphically by downloading the Supplementary Materials) is defined by a colour and a subset of co-occurring keywords: cluster one in red (Figure S1), with 21 keywords, encompasses technically oriented terminology, which includes snow water equivalent, machine learning, prediction, regression, optimization, and variability; cluster two in green (Figure S2), with 15 keywords, contains terms that describe resource governance and infrastructure through water management, decision-making, hydropower, storage, and electricity storage; cluster three in blue (Figure S3), with 14 keywords, focuses on monitoring and remote sensing through keywords such as in situ observations, validation, modis, verification, radar, and data assimilation; cluster four in yellow (Figure S4), with 12 keywords, shows a focus on hydrological processes with the presence of terms like runoff, evapotranspiration, basin, and swat; cluster five in purple (Figure S5), with 11 keywords, includes terms related to simulation-based approaches and resource vulnerability with terms such as simulation, efficiency, water–energy nexus, nexus, vulnerability, scarcity, and adaptation; cluster six in light blue (Figure S6), with 10 keywords, is centred around the term hydrological model linked to terms as calibration, land-use, soil erosion, and reservoir operation; cluster seven in orange (Figure S7), with nine keywords, is precipitation- and model-centred showing a strong thematic focus on precipitation patterns in the reviewed literature; cluster eight in brown (Figure S8), with nine keywords, is dominated by climate change showing its central role in the literature review and, connecting with terms as resources and impact reflects the focus on how climate change affects natural resources; cluster 9 in pink (Figure S9), with nine keywords, show a focus on groundwater analysis with terms such as groundwater, gis, remote sensing, and balance.

It is important to note that statistical co-occurrence of cluster positioning exists as a primary factor, but it does not establish formal disciplinary boundaries.

The preliminary thematic structure was refined to connect with the review objectives through a content-based classification of the 88 selected papers, which generated a conceptual table (

Table 1. Number of publications for each thematic subcategory.

Water management	Precipitation	30
	Water balance	17
	Groundwater	14
	Strategies	8
	Cryosphere	5
			TOT: 74
Energy management	Energy systems	2
	Renewable energy sources	3
			TOT: 5
Integration of water and energy management	Sectoral integration	4
	Water–energy nexus	5
			TOT: 9

) with three major thematic domains: “Water Management”, “Energy Management” and “Integration of Water and Energy Management” and their corresponding subfields, based on the specific focus of each study.

Water Management shows up in 74 articles, Energy Management is represented by five publications, and the Integration category includes nine publications. This breakdown highlights with specific numbers the predominance of water-related topics within the current body of literature.

4. Discussion

4.1. Water Management

4.1.1. Precipitation

Recent studies on snow and precipitation dynamics in mountain environments consistently highlight the importance of elevation in shaping precipitation inputs and snow accumulation. For instance, in the Southern Canadian Rockies, the comparison between uncorrected and bias-corrected measurements revealed that winter precipitation increases by approximately 61 mm per 100 m of elevation, three times the estimate obtained without correction, demonstrating how sensors can lead to significant underestimations in mountainous contexts [21]. The study points up the relevance of incorporating elevation-dependent corrections in precipitation gradient models.

The role of elevation corrections is also supported by satellite-based analyses. In the Aurino River Basin, a snow model supported by the assimilation of Sentinel-1 snow depth retrievals helped to correct altitude-related biases of traditional precipitation datasets. This approach enabled a more consistent reconstruction of snowfall elevation patterns across various precipitation products [22], deepening the relevance of remote sensing in refining spatial representations of snow inputs in complex terrain.

MODIS-based datasets have also contributed to this attempt by characterizing snow phenology (snow onset, duration, and melt timing) in relation to elevation and temperature regimes. In particular, cloud-gap-filled NDSI products and daily snow-cover probability datasets have demonstrated high agreement with in situ observations and Landsat images, offering improved spatial and temporal continuity across High Mountain Asia [23,24]. While these products are primarily observational, other studies have integrated satellite-derived snow metrics, such as MODSCAG fSCA, into seasonal prediction systems, resulting in better forecasts of runoff timing and volume, particularly in ungauged or poorly monitored basins [25].

In the context of snow water equivalent (SWE) estimation, machine learning approaches have shown notable success. In Iranian mountain regions, hybrid bagging models identified snow depth and density as the most informative predictors for SWE, outperforming traditional models in terms of Nash–Sutcliffe efficiency [26]. Complementary efforts in the Sierra Nevada leveraged only global meteorological datasets to produce high-resolution SWE simulations, which were validated against airborne lidar maps and demonstrated low error rates, although with some biases at higher elevations [27].

Several studies converge on the central role of snowmelt in alpine hydrology. Isotopic analyses in the Changbai Mountains attributed, on average, 42.6% of spring runoff to snowmelt contributions, with notable interannual variability linked to climatic and elevational gradients [28]. Distributed modelling on the Tibetan Plateau has revealed declining snow contributions to both streamflow and soil moisture since the late 1990s, driven primarily by warming-induced snow cover losses, with reservoir operations playing a secondary role [29]. In California, deviations between expected and observed streamflow volumes following droughts have been attributed to persistent root-zone moisture deficits, which inhibit snowmelt conversion into runoff, highlighting the need to account for antecedent soil conditions in hydrological forecasts [30].

The implications of climate change are particularly pronounced for compound events such as rain-on-snow (RoS). Modelling experiments show that RoS events will likely increase in frequency and severity beyond +1.7 °C of global warming, due to stronger atmospheric river incursions interacting with warmer snowpacks [31]. In parallel, snow sublimation has emerged as a significant loss mechanism in cold-arid environments, with empirical data from the Altai Mountains indicating annual sublimation rates averaging 14.3 mm, corresponding to 8.2% of total snowfall [32].

The coupling between snow and groundwater systems has been modelled in the North Saskatchewan River Basin, revealing that snow droughts and groundwater droughts propagate differently depending on ecological and geological settings. The temporal lag in signal transmission, shorter in mountain zones and longer in the plains, has critical implications for groundwater resilience under future climatic shifts [33]. In High Mountain Asia, SWE anomalies were found to contribute between 7% and 27% to terrestrial water storage changes, underscoring the role of seasonal snow in regional hydrological balances [34].

Efforts to improve hydrological forecasting have shown promising results. Seasonal forecasts that combine ensemble meteorological predictions with physically based snow models have demonstrated useful predictive skill up to six months in advance, particularly for snow depth and SWE in Alpine regions [35]. These approaches benefit significantly from the integration of satellite data products, which provide greater spatial coverage than traditional ground networks.

Precipitation-focused studies further support the added value of satellite observations in mountainous regions, albeit with limitations. In the Upper Indus Basin, increases in extreme precipitation events have been statistically linked to teleconnection indices such as ENSO and NAO [36]. Comparative evaluations of satellite precipitation products in the South China mountains and in the Himalayan region suggest that GSMaP and MSWEP demonstrated higher detection skill compared to CHIRPS and SM2RAIN, particularly in terms of correlation with ground-based observations and hydrological model performance [37,38]. However, in the specific mountainous basins tested, none of the products reliably captured peak flows without calibration, highlighting the necessity for local adjustment when using satellite-based precipitation estimates in hydrological modelling.

Land use also modulates precipitation and runoff dynamics. In the Tianshan Mountains, stable isotope analysis showed that up to 28% of summer rainfall in nearby mountain areas may derive from irrigation-induced atmospheric moisture recycling in adjacent oases [39]. In mountainous urban environments, simulations with the SWMM model revealed that the spatial arrangement of Low Impact Development (LID) infrastructures significantly affects runoff volumes and peak discharge, particularly on steep slopes [40]. Meanwhile, in high-altitude cold deserts of the Indian Himalayas, snowmelt harvesting using improved poly-tank systems has been shown to support irrigation and ecosystem resilience under declining snowfall and glacial retreat [41].

4.1.2. Water Balance

The reviewed literature reveals how mountain water balances are being reshaped by climate change and socio-economic pressures. On the Tibetan Plateau, ensemble modelling shows a climate-driven intensification of runoff and evapotranspiration [42], while in the Nepal Himalayas, warming, glacial retreat, and shifting monsoonal dynamics collectively alter streamflow regimes [43]. Yet, these changes are not spatially uniform: in southern Central Asia, lowlands are drying while highlands retain moisture, evidencing divergent basin-mountain trends [44]. In the Northern Tianshan Mountains, increased runoff from glacial melt is undermined by groundwater depletion and overextraction, threatening long-term water security [45].

Studies emphasize baseflow and streamflow partitioning as key components of mountain hydrology. In tropical alpine catchments, streamflow transit times fluctuate with seasonality and wetness, influencing vulnerability to drought [46]. Interpretable machine learning models based on numerical experiments improve baseflow segmentation and forecasting accuracy [47], while Random Forest models outperform process-based ones like SWAT in snowmelt-driven systems due to their ability to capture complex nonlinearities [48].

Human activities also reshape water balances. In the Indus Basin, rising upstream consumption could cut downstream dry season flows by 25%, straining existing transboundary agreements [49]. In Chongqing, rapid urbanization has led to pronounced spatial mismatches between supply and demand [50], while in the Northern Tianshan Mountains, unplanned irrigation now exceeds 35% of total water use due to cropland expansion [51].

Data scarcity in mountain regions makes accurate water balance estimation challenging. In the Eastern Himalaya, gridded precipitation datasets show mixed performance: while CFSR performs well, others like APHRODITE and PERSIANN are inadequate without correction [52]. In highly managed alpine systems, digital twin models integrating remote sensing and ground data enhance distributed water balance assessments [53]. Hybrid models combining neural networks and optimization algorithms also improve evaporation predictions in arid regions, where losses are difficult to quantify [54].

Lastly, snow management in ski resorts modifies local water balance. Snowmaking and grooming delay snowmelt and shift runoff toward spring, with limited annual impact but notable seasonal redistribution, particularly in small alpine catchments [55].

4.1.3. Groundwater

Groundwater dynamics in mountainous regions emerge from the interplay of climatic variability, terrain complexity, and anthropogenic pressures, collectively shaping recharge processes and resource sustainability [56,57]. GIS-based models integrating the Analytic Hierarchy Process (AHP) consistently identify terrain parameters such as slope, land cover, soil texture, and drainage density as dominant recharge drivers, sometimes with greater explanatory power than precipitation alone [58,59].

The distribution of forested regions with permeable soils and mild slopes aligns with recharge-prone areas, and by contrast, urban and agricultural zones predominantly exist in low-recharge areas, creating a spatial pattern that worsens under changing climate and water demand regimes [59,60]. The gap between these assessments demonstrates the critical need to incorporate them into regional planning systems to enhance resilience against changing climate and water usage patterns [61]. AHP-GIS models, which demonstrated approximately 87% accuracy in Alaska, serve as effective recharge mapping proxies for areas with limited direct field data [58], and in hydrogeologically complex environments, tracer-based and numerical modelling approaches clarify subsurface flow paths, improving surface analyses [62,63].

Recharge-favourable zones are typically wooded with pervious soils and gentle slopes, while urban and agricultural areas often overlap low-recharge areas, demonstrating a spatial mismatch that heightens vulnerability under changing climate and water demand regimes [59,60]. This disconnect highlights the imperative to incorporate such evaluations in regional planning schemes to enhance resilience under changing climate and future water use [61]. Where field data are sparse, AHP-GIS models (∼87% accuracy in Alaska) provide strong proxies for recharge mapping [58], and in hydrogeologically complex environments, tracer-based and numerical modelling approaches clarify subsurface flow paths, improving surface analyses [62,63]. Together, these methods provide a scalable framework for groundwater assessment across diverse mountain contexts.

Land use critically modulates recharge resilience during droughts: groundwater-fed irrigation systems in Northern Italy experienced depletion up to 76% above baseline during the 2022 drought, while surface-water-fed systems were vulnerable to reductions in snowmelt supply [61]. Parallel GRACE satellite observations in China’s Taihang Mountains documented significant groundwater storage declines (−21.22 mm/year), predominantly driven (96%) by anthropogenic extraction [57]. These findings underscore human demand as the primary stressor in mountain aquifers, often outweighing climate variability.

Climate change further influences recharge via altered evapotranspiration (ET) and atmospheric CO₂ effects: in the Austrian Alps, experimental warming increased ET by 17% and reduced recharge by 47%, while elevated CO₂ partially mitigated ET increases and enhanced recharge. Nonetheless, warming remained the dominant driver, resulting in net groundwater availability decline [64]. These responses are scale-dependent, with catchment-level sensitivities exceeding plot-scale effects, complicating extrapolations. As recharge dynamics continue to be modulated by climate, land use, and topography, integrated multi-scalar, interdisciplinary approaches are essential to sustain groundwater resources under evolving environmental pressures.

4.1.4. Strategies

A line of reviewed studies highlights the complex challenges and opportunities in managing water resources in mountainous environments, where hydrology, land use, climate, and socio-cultural factors interact at multiple scales. In Mediterranean mid-mountain basins, vegetation regrowth (natural or human-induced) after land abandonment reduces hydrological connectivity and surface runoff by increasing roughness and interception, contrasting with shrub clearing that enhances runoff, showing how land management distinctly influences catchment hydrology [65]. Meanwhile, in the transboundary Agios Germanos River basin, climate change combined with human water withdrawals critically reduces discharge and intensifies water stress, illustrating different mechanisms of water availability decline [66].

Exploratory Modelling and Analysis (EMA) suggests that irrigation efficiency improvements with reservoir management yield water sufficiency outcomes across varied futures, requiring multi-scenario approaches to address deep uncertainty in data-scarce Andean regions [67]. Native water management knowledge from Southern Chinese villages supports local water resilience through their traditional water collection and drainage methods [68]. Similarly, historic recharge channels within the Sierra Nevada and Peruvian Andes act as large-scale nature-based solutions that slow water flow and increase aquifer recharge while improving water quality [69].

Different locations within the Qinghai Lake Shaliu basin exhibit various vegetation zones that either generate water or retain water or use water through evapotranspiration and soil moisture processes, showing the key role of spatial heterogeneity [70]. A Central Asian study supports the observation showing that elevation variability appears alongside complex responses to warming and precipitation changes [71] underscoring the need for site- and elevation-specific management.

Lastly, vulnerability assessments in regions such as the French Pyrenees further highlight climate stress challenges to hydropower and environmental flows, stressing the importance of adaptive governance capable of monitoring thresholds and responding effectively [72].

4.2. Energy Management

The limited selection of energy management reviewed studies reveals recurrent patterns across different regions, reflecting the optimization of local energy systems with distinct strategies. A first pattern is represented by integrations with existing infrastructures: in Switzerland, a high-altitude floating photovoltaic installation is co-located with alpine reservoirs [73]; in Austria, small hydropower units are incorporated in municipal water distribution networks [74]; and in southern Italy, photovoltaic panels and battery storage form a hybrid system with local energy distribution [75]. Adaptation and operational flexibility constitute a second pattern: a demand-based reservoir management approach replaces a static energy logic with a dynamic energy-demand driven one in France [76] and in Elazığ, the implementation of an online primal-dual optimization algorithm in the community energy storage system dynamically schedules charging and discharging requests in real-time [77]. Environmental and efficiency benefits emerge from the literature: the Swiss floating photovoltaic systems contribute to CO₂ emission reductions [73], the demand-based operations in France increase hydropower and river discharge accuracy [76], the Turkey real-time management maintains systems performance near optimal offline solutions [77], micro-hydropower units increase profitability and energy output in Austria [74], and the Soveria Mannelli energy community shows an intensification of energy self-sufficiency and a reduction in CO₂ emission [75].

4.3. Integration of Water and Energy Management

The convergence of water and energy in mountain regions manifests two complementary axes: sectoral convergence for maximizing single-use systems and more explicitly water–energy nexus-oriented strategies. In sector-based integration, a clear pattern is that some of the most advanced monitoring systems or adaptive modelling algorithms are developed for specific operational environments. At the site level, the Integrated Energy Management System (IEMS) in the Madonna di Campiglio ski resort integrates real-time data streams concerning snowmaking, ski lift operations, and energy consumption in buildings to produce key performance indicators (KPIs) to fine-tune responsive energy management [78]. Likewise, the AquaVar Decision Support System (DSS) in the Var catchment uses a modular, user-oriented approach to modelling the hydrological processes [79]. At larger scales, the MESH system incorporates a cold-region hydrological component that includes permafrost dynamics, snow sublimation, and glacier melt that can provide better predictive skill at the basin scale [80]. Together, these cases illustrate a common sectoral theme of data-informed models and real-time monitoring to enhance operational control and prediction in energy use and water resources.

The transition from sectoral to nexus-oriented strategies often builds on these foundational capabilities, adding explicit inter-sectoral linkages and multi-objective optimization. A case from Quito illustrates an intermediate position, where water provision, water quality, energy costs, and biodiversity conservation are balanced through multi-objective modelling to have a multi-level analysis on water usage [81], demonstrating that single-sector insights can be leveraged for broader nexus-oriented solutions. The Sustainable Water Optimization Tool (SUWO) operationalizes a similar principle at the basin scale, integrating water, energy, food, and ecosystem services through genetic algorithm-based optimization [82]. Beyond modelling, operational innovations embody nexus patterns by resolving temporal or spatial trade-offs: Seasonal Pumped Hydropower Storage (SPHS) schemes in Central Asia synchronize upstream hydropower generation with downstream irrigation needs, reducing water losses while maximizing energy utility [83]; pumps-as-turbines (PaTs) in urban water networks convert pressure fluctuations into energy while simultaneously minimizing leakage, reflecting micro-scale dual-use benefits [84]; and facility-scale hydroelectric systems applying Advanced Process Control (APC) demonstrate model-predictive allocation, optimizing water use across dual reservoirs to achieve energy targets with minimal waste [85]. In these cases, nexus implementation is no longer a matter of disconnected optimizations but a matter of a conscious management of multiple goals over scales, framed in technological and ecological types.

5. Conclusions

5.1. Research Gaps and Future Perspectives

A cross-reading of the reviewed literature reveals an uneven landscape of knowledge production across the domains of water management, energy management, and their integration in mountainous contexts. Knowledge asymmetry shows fundamental differences in methodological development, thematic scope, and systems thinking abilities. The research community has dedicated extensive time to studying water management, especially snow processes, hydrological dynamics, and climatic drivers, while energy management and integrated water–energy management show limited and fragmented investigation (Figure 5, Table 1) despite their rising importance under the pressure of climate change and infrastructure complexity.

From our perspective, the imbalance between water and energy research in mountainous regions emerges from systemic, institutional, and socio-technical dynamics rather than accidental trends. Research into water systems has gained advantages from well-established monitoring networks alongside established methodological frameworks and widespread public understanding because it connects directly with disaster risk reduction, agricultural, and ecological security needs. Energy-focused studies, in contrast, remain fragmented, constrained by data access, sectoral governance scales, and lower immediacy in public perception. Systemic connections generate feedback loops through which mature water knowledge draws funding and guides policy development and research agenda formation, yet energy research remains distant from mountain-specific studies because of its emerging status and fragmented institutional monitoring. For those reasons, work related to energy systems, along with their interconnections and integrations with water topics, may remain limited for historical, institutional, and social factors that create structural barriers in the literature.

In the field of water management, the increasing use of satellite data and machine learning for snow and precipitation modelling, while promising, still suffers from insufficient ground validation in remote or high-altitude zones. Moreover, key processes such as snow sublimation, rain-on-snow interactions, and antecedent soil moisture effects on runoff generation remain underrepresented in operational forecasting frameworks. The role of land use (be it through vegetation change, urban expansion, or agricultural practices) in modulating both precipitation recycling and runoff responses is emerging as crucial, but models capable of dynamically integrating this coupled feedback across scales are still lacking. Similarly, while advances in digital twin modelling and hybrid simulation have improved water balance estimation, their ability to capture anthropogenic alterations, legacy infrastructure impacts, and shifting socio-hydrological regimes remains limited. In the domain of energy management, there is a marked absence of comparative assessments, long-term performance evaluations, or scenario-based explorations that could inform the scalability, interoperability, and resilience of energy interventions in alpine settings. Moreover, the socio-political dimensions of energy governance, such as community ownership, regulatory fragmentation, or cross-border coordination, are rarely addressed, leaving a conceptual vacuum in understanding how energy systems can evolve under increasing environmental and institutional pressures. This fragmentation is also evident in the field of integrated water and energy management; in fact, the reviewed literature tends to treat integration as an additive process linking energy to water or vice versa rather than as a transformative redesign of resource systems that recognizes interdependencies, trade-offs, and co-benefits across scales and actors. This disparity in scholarly attention fails to offer integrated frameworks and does not adequately explore the institutional, financial, or cultural conditions under which water–energy integration can be operationalized in mountainous systems, which are not only biophysically intertwined but also socio-technically co-evolving.

Another important aspect of the research results is a geographical disparity in the study areas (Figure 4) of selected papers: research on management practices in mountain areas appears markedly uneven across Europe. While the Western regions benefit from a comparatively rich body of scholarship, studies addressing the Eastern part of the continent remain scarce, and the same situation is revealed in Norway and Sweden, where, despite the evident relevance of their geographical context, scholarly contributions are virtually absent. A similar imbalance is found in the Americas: South America, in particular, is represented by very limited territorial coverage. Africa, however, presents the most pronounced gap, with merely one work identified across the entire continent. In contrast, Asia offers a more extensive and geographically dispersed set of investigations, reflecting a stronger and more sustained academic engagement with mountain resource management.

By analysing the literature contents, a Future Agenda table (

Table 2. Future Agenda.

Water	Developing innovative and extensive ground validation frameworks for mountain regions to improve the reliability of satellite-based and machine learning hydrological models. Integrating hydrometeorological processes into forecasting frameworks to enhance predictability. Creating adaptive models that combine human-made alterations, legacy infrastructure, socio-hydrological transformations and land-use feedback mechanisms to improve mountain environment water system modelling for policy applications.
Energy	Comparing long-term performance of energy systems in mountain contexts. Evaluating energy systems’ scalability, interoperability, and resilience under climatic constraints. Exploring socio-political dimensions related to energy governance systems through interdisciplinary research approaches.
Integration	Exploring integration as a transformative process of mountain areas. Studying comprehensive decision-making frameworks that describe interdependencies, trade-offs, and co-benefits among sectors. Investigating the institutional, financial, and cultural enablers and barriers to integration in mountain regions. Probing conditions for the implementation pathways, stakeholder alignment, and long-term system resilience.

) was created that aims to propose different solutions to fill the gaps along the three macro categories examined in the research, offering sectorial improvements.

This sectorial analysis of the research gaps and their implications in future research directions sets in place an important point for the conclusion of this review, which, in addition to expressing how to fill in literary gaps, also wants to integrate them into an all-encompassing discourse that is based on three interconnected transformations.

The first point concerns the systemic co-design of resource systems as the most pressing need. The research should not be confined to optimal sectoral solutions but aim at co-managing water supply with other components of the socio-ecological assemblages that it is coupled to, like energy storage, generation of ecological flows, and human demands. It needs realization experimental setups mixing nature-based solutions, multipurpose reservoirs, and distributed gen-storage systems. Models need to account for water–energy nexus dynamics, evaluate the trade-offs between the different options under different climatic and operational conditions, and measure the adaptability and flexibility of integrated systems. Studies of this kind will provide actionable knowledge for both practitioners and policymakers to make robust and adaptive decisions under uncertainty.

Second, it is imperative to develop knowledge that is comparable and transferable across regions. Almost all present research studies are still case-group studies without conclusive generalization. Priority research needs are to develop harmonized modelling protocols, standard measuring indicators, and cross-regional benchmarking tools for assessing the effectiveness, robustness, and co-benefit delivery of the integrated system. Comparing across alpine, arid, tropical, and temperate mountain zones will demonstrate generalizable design principles, governance arrangements, and local constraints. An interdisciplinary cooperation between hydrologists, energy engineers, and socio-environmental scientists is needed, in order to develop the work related to the technical, ecological, and institutional aspects together.

Third, there is a need for an improved social and institutional anchoring of technical publication to increase the legitimacy and feasibility of integration strategies. In future work, community engagement, stakeholder mapping, participatory scenario development, equity concerns, and other decision-making perspectives beyond conventional optimization must be explicitly integrated. We need to better understand socio-cultural values, the regulatory space, and the adaptive capacity, especially when we use nexus-approaches, such as in nexus-oriented approaches where a lot depends on human behaviour and governance. This kind of interdisciplinary grows out of social sciences, policy studies, and engineering orientation, such that the combined solutions are technically good and socially and technically resilient.

In sum, while progress in water management research offers a valuable foundation, the path forward lies in cultivating a transdisciplinary agenda that treats water and energy not as discrete sectors to be coordinated post hoc, but as co-evolving systems requiring transdisciplinary insight and place-based understanding. Mountain environments offer a critical challenge and a unique opportunity to start this paradigm shift and bridging the current divide in knowledge production will not only advance academic understanding, but also contribute to the design of more just, resilient, and adaptive resource systems.

5.2. Limitations of the Review

Methodological limitations emerged in the construction of this review, all of which should inform the interpretative range of its results. Although the construction of the search string was carefully developed, it was based on preselected terms that might not capture all the semantic variability and conceptual nuances in the literature regarding the integrated water and energy management in mountain areas. This semantic constraint may have resulted in the exclusion of studies adopting different terminology or disciplinary perspectives. Moreover, the decision to limit the analysis to papers published from 2022 to 2025, although justified in relation to the goal of capturing the latest advances of the science, led to the exclusion of earlier contributions that might have built essential groundwork for understanding current research trajectories. Another limitation is the structural disparities in the classification systems of Scopus and Web of Science: the differences in configuring domain thematic nodes between the two databases added some asymmetry in the selection process, which could have some influence on the comparability of the filtered results. Lastly, the exclusion of grey literature, consisting of institutional reports, technical documents, and unreviewed local studies, restricted the inclusion of essential context-specific knowledge that could play an important role in applied environmental research.