Search Results (137)

The Wadi Al-Ahsaba watershed is an arid to semi-arid catchment situated in southwestern Saudi Arabia, characterized by intermittent surface flow, high evaporation and low rainfall, and a dam reservoir built for flood control. The work aims to assess hydrological and anthropogenic controls on surface and groundwater quality, pollution status, and human health risks using an integrated approach of hydrogeochemical analysis, multivariable statistics, and water quality and contamination indices. A total of 21 water samples (15 surface water, 6 groundwater) were analyzed for general chemistry, major ions, and trace elements. Hydrogeochemical analysis and principal component analysis (PCA) were implemented to differentiate the geogenic from anthropogenic control on water quality. The pollution status and associated risk were evaluated using water quality index (WQI), contamination degree (Cd), Hazard Quotient (HQ), and Hazard Index (HI). Results suggest limited surface–groundwater interaction, with surface water dominated by Ca–Mg–HCO₃ facies, indicating recent recharge and limited water–rock interaction, whereas groundwater exhibits mixed Ca–Mg–Cl and Ca–Na–Cl–SO₄ types, revealing longer residence time and water–rock interaction. Nitrate (9.5–109 mg/L) and TDS (522–1003 mg/L) exceeded drinking water standards in 90% and 95% of tested samples, respectively, and WQI ranged from 43 to 134, reflecting excellent to poor water. High non-carcinogenic risk from nitrate was observed, especially for infants. The study concluded that the geogenic processes (water–rock interaction, evaporation, and mineral dissolution) control the general chemistry of tested water, while anthropogenic input from wastewater and agriculture input are likely contributors to nitrate contamination. The study contributes to the understanding of arid wadi-dam systems by revealing how limited recharge, hydrological connectivity, and episodic flow control contaminant transport and persistence, underscoring the critical role of integrated hydrological analysis and land use management in safeguarding freshwater resources in arid environments. Full article

The 2019 Mississippi River floods were among the most severe in recent U.S. history, impacting 11 states and driven by multiple tributary flood events rather than a single episode. This study focuses on the Lower Mississippi River Basin in Mississippi, examining how flood frequency interacts with land ownership patterns to influence agricultural losses in the Yazoo–Mississippi Delta. Using Sentinel-2 imagery within Google Earth Engine, land use and land cover were classified with a random forest algorithm, followed by change detection and a flood recurrence–persistence modeling framework to map and characterize inundation. Results indicate that mid-year floods (April–July) caused the greatest crop losses, particularly in soybeans (4475 ha), cotton (501 ha), and corn (546 ha). Most impacts were associated with short-duration, low-recurrence floods, which affected many structures (1812) and extensive agricultural areas due to their broad spatial reach. Small agricultural parcels (≤48 ha) experienced the highest proportional exposure across flood zones, while medium and large parcels showed comparatively lower vulnerability. These findings highlight the importance of targeted resilience and mitigation strategies that account for flood frequency, land use, and land ownership patterns across the Delta. Full article

This paper develops a Business Resilience Index (BRI) that measures county-level resilience to natural disasters at a county-quarter frequency for the United States over 2014–2024. The index integrates high-frequency labor market outcomes from the Quarterly Census of Employment and Wages with flood insurance policy information from FEMA, disaster damages from the NOAA Storm Events Database, and social and health determinants from County Health Rankings. Starting from a broad candidate set, we apply an interpretable feature-screening pipeline to retain 79 variables and then use principal component analysis to extract four orthogonal structural dimensions of resilience: market scale, socioeconomic resilience, urban density risk, and industrial economy profile. We construct a domain-weighted strategic index and benchmark it against data-driven and equal-weight alternatives, showing that county rankings are highly stable across weighting schemes. To evaluate whether the BRI aligns with recovery behavior under acute shocks, we implement a matched difference-in-differences event study around two major flood episodes—Texas in 2015Q2 and North Carolina in 2018Q3. Conditional on exposure intensity and matched comparability, higher pre-event BRI counties exhibit earlier stabilization and a stronger post-event employment path relative to lower BRI counties, with differences in magnitude and timing across cases. Overall, the BRI provides an interpretable, high-frequency baseline for identifying capacity constraints that may slow recovery and for supporting preparedness targeting and post-disaster monitoring. Full article

Warm rain events occur when moist air masses containing elevated precipitable water produce high rainfall rates capable of generating local flash floods. Catalonia, located on the northeastern Mediterranean coast of the Iberian Peninsula, is regularly affected by such episodes: approximately 70% of daily precipitation events exceeding 10 mm with fewer than ten cloud-to-ground lightning flashes can be classified as warm rain. The current research aimed to identify the meteorological conditions most conducive to heavy warm rain episodes in Catalonia. These cases are commonly associated with flash flood episodes in the study region. We utilized rain gauges, lightning data, radar, and model fields, combined with radio sounding profiles. First, we identified and characterized warm rain cases, and second, we have selected some relevant cases to characterize the phenomenon. These events occur predominantly along the Catalan coast during the warm season, typically following the passage of a cold front, and are associated with shallow convective clouds producing little or no lightning. However, the key determining factor is a characteristic vertical thermodynamic profile: a moist and saturated lower troposphere with high precipitable water beneath a low- to mid-level thermal inversion, and weak instability concentrated near the surface. Furthermore, local wind convergence plays a principal role in the rainfall pattern. Full article

This study analyses two wetlands within the Medina del Campo groundwater body (Duero River Basin, Spain) to reconstruct flood patterns and quantify the hydrological volumes involved in episodic inundation. We integrate Sentinel satellite imagery (2015–2024), targeted field campaigns (2024–2025), and preliminary water-balance assessments (2015–2022). Calculations were constrained to the inundated cells of each wetland bed to reduce spatial heterogeneity issues. For Laguna de los Lavajares, an initial standing water depth was assumed to estimate infiltration losses more accurately. We discuss the primary sources of uncertainty—particularly the representation of atmospheric losses as evaporation versus evapotranspiration—and recommend computing water balances for wet, average, and dry years to capture interannual variability. Key findings include the identification of distinct hydroperiods for each wetland, the dominant role of infiltration in the water balance of Laguna de los Lavajares, and the critical influence of vegetation-driven evapotranspiration in Laguna Redonda. Full article

The northeast monsoon prevailing over southeastern China in late seasons, generally from October to March, frequently generates water level anomalies upstream of the Taiwan Strait (TWS) that reach the coastal waters of Guangdong in South China, and, with compounding astronomical high tides, elevate coastal flood risk over the region. The risk of coastal flooding or sea inundation is further heightened when monsoon forcing co-occurs with storm surge brought by late-season tropical cyclones (TCs). This study integrates tide gauge observations from Hong Kong (HK) and its vicinity together with Delft3D Flexible Mesh simulations to diagnose a tide-modulated anomaly wave mechanism. Observations show that anomalies originating in or near TWS arrive in HK with station-dependent phasing. These water level anomalies exhibit a characteristic ~6 h periodicity west of the Taiwan Shoal, and display peaks that systematically align with the astronomical high tide. Time–frequency analysis reveals a wave period transformation from ~12 h north of Dongshandao over the coast of southeastern China to ~6 h west of the Taiwan Shoal. We test the hypothesis that wind-forced water anomalies generated in or near TWS undergo shoal-modulated nonlinear tide–wind interaction and tidal-current advection that transform their dominant period and phase-lock them to the tide, producing four anomaly peaks per day downstream and station-dependent phasing in HK. Hindcasts of the November 2024 monsoon episode reproduce the observed timing, periodicity, and spatial transition, while constituent experiments demonstrate that semi-diurnal forcing entering via the TWS is the primary driver of the ~6 h signal, with the Taiwan Shoal acting as the modulation locus. Accurate water level forecasts for the Guangdong coast, therefore, need to incorporate upstream wind forcing over the TWS and bathymetric controls around the Taiwan Shoal, with practical implications for compound flood risk during spring tides and co-occurring monsoon and/or TC events. Full article

Pasture ecosystems provide essential ecosystem services, yet poisonous plants create persistent veterinary and economic risks. We examined how hydroclimatic variability restructures the poisonous-plant assemblage across three Central Kazakhstan rangelands during an extremely dry year (2023) and an exceptionally wet year (2024). A total of 32 toxic vascular plant species were recorded. Xeromorphic pastures maintained a stable floristic core across years, whereas the wet year triggered recruitment of wet-associated poisonous taxa (hydrophytic/hygrophytic group) exclusively in the Nura River floodplain and increased species richness. Thus, interannual variability was controlled by hydrologically sensitive habitats rather than wholesale community turnover. The principal grazing hazard was associated with flood-related species (e.g., Cicuta virosa, Oenanthe aquatica) and persistent forage contaminants (Datura/Hyoscyamus, Lolium temulentum). These findings indicate that toxic-plant risk follows an asymmetric seasonal pattern: episodic post-flood hazard in floodplains combined with constant background risk in steppe pastures. Therefore, grazing management should integrate event-based monitoring of wet habitats with continuous forage-quality control. Full article

Palynological analysis of seventy-seven cutting samples from six boreholes in the Marañón Basin (northeastern Peru) has identified five distinct Neogene marine incursion events (ME-1 to ME-5), challenging existing models that depict them as short-lived episodes. The diverse palynological assemblages, comprising spores, pollen, freshwater algae, and critical marine indicators—including dinoflagellate cysts, foraminiferal test linings, and copepod eggs—reveal that these incursions were protracted and recurrent, each associated with a maximum flooding surface and bounded by intervals of continental sedimentation. The stratigraphic record shows the earliest event ME-1 (Aquitanian to Late Burdigalian, 23.03–17.7 Ma) identified across all studied wells. ME-2 (latest Burdigalian to Middle Langhian, 17.0–16.1 Ma) is also recorded basin-wide. ME-3 (latest Burdigalian to earliest Langhian 16.5–15.7 Ma) registered in two wells. ME-4 (Late Langhian to latest Serravallian, 14.6–11.62 Ma) registered in only two wells and ME-5 (Early Tortonian, 11.6–10 Ma) is documented exclusively in the southernmost well, culminating in Zanclean (~5.5–3.6 Ma) mangrove development. We interpret the ingress routes for ME-1 to ME-3 to be westward via the Marañón Portal or northward from the Caribbean, associating them with the Proto-Pebas and Pebas systems. In contrast, ME-4 would also be from Amazon trunk or Paraná Portal associated with the Pebas Phase, and ME-5 likely originated from the south through the Paraná Portal, linking it to the Acre Phase. These results demonstrate that Miocene marine incursions into western Amazonia were not brief episodes but represented prolonged periods of marine influence, facilitated by sustained subsidence in the Marañón retro-arc foreland basin. This history reveals a dynamic connectivity throughout the Neogene, with marine conditions acting as persistent biogeographic barriers that critically shaped the region’s Miocene biodiversity patterns. This refined chronology provides a comprehensive regional framework, significantly advancing our understanding of Amazonian paleogeography. Full article

This study analyzed the hydroclimatic functioning of the Lake Fitri basin (Chad) by combining rainfall records, in situ hydrological observations, water balance analysis, and spatial remote sensing data. Results show a strong Sahelian climatic control, with rainfall concentrated in a short-wet season (July–September) and potential evapotranspiration largely exceeding precipitation. Batha River flows are highly seasonal, generating short flood pulses that drive lake level fluctuations and aquifer recharge. Water balance estimates indicate that recharge is limited and episodic (approximately 70–120 mm in 2020), representing only 14–24% of annual rainfall, occurring almost exclusively during extreme rainfall events. Compared with Lake Chad, Lake Fitri is more directly sensitive to local rainfall variability, reflecting its dependence on a single tributary. Overall, the findings underline the fragility of this hydrosystem and the need for reinforced monitoring and integrated management to ensure sustainable water resources under increasing climatic variability. This work constitutes the initial reference for the hydroclimatic characterization of Lake Fitri, thanks to a methodology combining in situ and satellite data. Full article

This study examines the historical relationship between water management and epidemic diseases in the Region of Murcia (Southeast Spain) between the 16th and 19th centuries. It focuses on two major pathologies—yellow fever and cholera—which, despite differing transmission mechanisms (vector-borne and waterborne, respectively), both depended critically on aquatic and semi-endorheic ecosystems. By analysing archival records, parish death registers, and historical reports of floods and droughts, the paper demonstrates how inadequate hydraulic infrastructure and poor sanitation practices intensified epidemic outbreaks. At least five large-scale epidemic episodes (1804, 1834, 1854, 1865, and 1885) coincided with extreme hydrological events, indicating a clear correlation between water governance failures and mortality peaks. Conversely, periods of effective state intervention through regulation and infrastructure maintenance reveal a marked reduction in disease incidence. The results highlight that water governance was not only a technical challenge but also a socio-political determinant of public health. These historical insights remain relevant today, particularly as climate change exacerbates water-related risks worldwide. Understanding the long-term interactions between ecology, infrastructure, and disease contributes to current debates on environmental resilience and sustainable management of water resources as key components of collective health and social stability. Full article

In recent decades, the number of beavers both in Russia as a whole and its European part has increased significantly due to reintroduction, conservation measures, etc., which has partially resulted in changes in the water regime, especially of small rivers, erosion and sedimentation processes in them, and a partial transformation of riparian ecosystems. Based on the results of 2022–2024 field work and laboratory studies, spatiotemporal features of changes in the rate of sedimentation, grain-size distribution, and organic matter content in bottom sediments of beaver ponds in 15 small rivers of the southern forest, forest–steppe and steppe landscape–climatic zones of the Volga–Kama region of the East European Plain were revealed. It was found that the highest rates of sediment accumulation, the largest proportion of fine grain-size fractions (<0.01 mm), and the highest content of total organic matter in the bottom sediments of beaver ponds are observed in small rivers of the steppe zone, while the smallest indicators of the above are characteristic of small rivers in the southern forest zone. Moreover, the highest rates of sedimentation are observed in the ponds of the upper reaches of small rivers in the studied zones. The distribution of sedimentation rates in beaver ponds demonstrates distinct seasonal dynamics: the highest rates of sediment accumulation are observed during the spring flood caused by snowmelt, while lower rates occur during the summer–autumn low-water season with episodic rainfall flood events, especially during a prolonged absence of the latter. Using two rivers in the forest–steppe zone as an example, the rates of total sedimentation in beaver ponds were identified (1.3–14.7 cm per year), which correlate well with the rates of sedimentation in beaver ponds of small rivers in various lowland/upland regions of Europe. Full article

Flooding episodes caused by a heavy rainfall event have become more frequent, especially during the rainfall season in Botswana, which poses some socio-economic and environmental risks. This study investigates the capability of the Weather Research and Forecasting (WRF) model in simulating a heavy rainfall event that occurred on 26 December 2023 in Mahalapye District, Botswana. This event is one among many that have negatively impacted the lives and infrastructures in Botswana. The WRF model was configured using the tropical-suite physics schemes, i.e., (Rapid Radiative Transfer Model, Yonsei University planetary boundary layer scheme, Unified Noah land surface model, New Tiedtke, Weather Research and Forecasting Single-Moment six-class) on a two-way nested domain (9 km and 3 km grid spacing) and was initialized with the GFS dataset. Gauged station data was used for verification alongside synoptic charts generated using ECMWF ERA5 dataset. The results show that the WRF model simulation using the tropical-suite physics schemes is able to reproduce the spatial and temporal patterns of the observed rainfall but with some notable biases. Performance metrics, including RMSE, correlation coefficient, and KGE, showed moderate to good agreement, highlighting the model’s sensitivity to physical parameterization and resolution. The results of this study conclude that the WRF model demonstrates promising potential in forecasting extreme rainfall events in Botswana, but more sensitivity tests to different parameterization schemes are needed in order to integrate the model into the early warning systems to enhance disaster preparedness and response. Full article

Urban coastal areas along the Mediterranean are exposed to short-duration convective rainfall, producing infrastructure disruptions and flood-related impacts. This study analyzes 45 rainfall episodes in the Metropolitan Area of Barcelona between 2014 and 2022, combining radar products, rain gauge observations, and urban-scale impact datasets. Storm radar tracking enabled the identification of key spatiotemporal features and assessment of short-term forecasting performance. Convective cells were typically short-lived, lasting less than 30 min in most cases. The main goal of the research has been the comparison between VIL density (DVIL) radar field and short-duration rainfall intensity provided by rain gauges. This is the first study comparing both data types, being a pioneer in this field. We have found a linear relationship between both data types, with weaker values for larger values. More persistent cells had higher DVIL values, observing a difference in behavior with a break point at 2 g/m³. The tracking and nowcasting system were evaluated based on its ability to anticipate convective precipitation. It achieved good scores values (POD of 0.73 and FAR of 0.33), considering the difficulties of tracking this type of convective system. Finally, false alarms associated with elevated DVIL values suggested the difficulty of capturing storm severity by surface-based precipitation measurements. Full article

In Sicily, many natural water bodies were reclaimed over the last two centuries for malaria control and agricultural expansion, causing widespread habitat loss. Some of these former ponds (still locally called “lakes”) reappear occasionally after extreme rainfall, temporarily restoring aquatic habitats but remaining poorly documented. We confirm the occurrence of such episodic ponds in central Sicily (Sommatino–Riesi) and present one of these ponds (Lago Montagna) as a case study. Combining satellite observations with field surveys conducted during a spring 2025 inundation, we document repeated episodes of flooding and a remarkable aquatic flora, including charophytes and other taxa of conservation interest. Episodic inundation events, therefore, act as transient refugia and stepping stones for regional biodiversity within an otherwise dry landscape. Because these systems commonly escape routine monitoring and legal protection, we argue they should be explicitly recognized in regional conservation planning and long-term monitoring programs. Moreover, the integrated remote-sensing approach used here allows the detection of overlooked temporary wetland ecosystems and provides fine-scale hydrological insights often missed by sparse weather station networks or satellite-derived rainfall data. Full article

This study presents an economic risk evaluation of buildings in Samoa exposed to extreme sea level (ESL)-driven episodic flooding and permanent inundation from relative sea level (RSL) rise. A spatiotemporal risk analysis framework was applied at the building object level to calculate monetary loss, expressed as the exceedance probability loss (EPL) and average annual loss (AAL). Economic risk was enumerated at national and district levels between the period 2020 and 2140 based on RSL projections for medium confidence Shared Socioeconomic Pathways (SSPs). Over this century, national AAL for buildings from ESL flooding in 2020 is expected to double by 2100 (USD 47–51 million). Under high emissions scenarios SSP3-7.0 and SSP5-8.5, AAL rates decelerate after 2100 as permanent inundation loss increases. District level risk variability is evident. For example, Tuamasaga on Upolu Island accounted for 44% of national 100-year annual recurrence interval losses, while AAL for Aiga-i-le-Tai and Va’a-o-Fonoti over this century reaches 8% of total district building replacement values. Our model approach has potential future applications to evaluate spatiotemporal risk distribution for a broader range of socioeconomic impacts that may occur beyond directly affected flood inundation areas. Full article