Orals: Tue, 5 May, 10:45–15:45 | Room 2.44
Climate change impacts on human systems increasingly emerge through hydrological extremes that generate complex socio-economic vulnerabilities across sectors. However, traditional risk assessments often emphasize physical hazards rather than how climate-driven hydrological changes cascade through ecosystem services to affect livelihoods, infrastructure, and adaptive capacity. To translate climatic scenarios into river discharge projections for the Lower Danube, we employed the Europe-HYPE (E-HYPE) hydrological model. This semi-distributed, process-based model simulates water balance components and river flow across hydrological response units. E-HYPE has been configured for pan-European applications and evaluated against observed flows across multiple basins. For the historical reference period (1971–2000), we used the HYPE reanalysis dataset at the Brăila gauge to characterise the baseline hydrological regime. Daily meteorological forcings in the reanalysis reflect observed and interpolated inputs that drive hydrological processes (e.g., rainfall, temperature). For future discharge projections (2001–2100), we constructed an E-HYPE ensemble of eight members by forcing the model with bias-adjusted meteorological inputs derived from multiple regional climate models under two Representative Concentration Pathways (RCP4.5 and RCP8.5). These forcings provide consistent daily temperature and precipitation inputs that reflect alternative greenhouse gas concentration trajectories through to 2100. The ensemble captures structural and forcing uncertainty in the projected hydrological response.
IWe used a hydrological impact dataset providing water-related Essential Climate Variables (ECVs) and Climate Impact Indicators (CIIs), derived from bias-adjusted regional climate simulations from the EURO-CORDEX. The dataset includes daily mean river discharge produced using a multi-model hydrological setup based on the E-HYPEcatch model at a pan-European scale, available at the catchment level and on a 5 km × 5 km grid. We have extracted the simulated daily discharge at the Brăila station, for two climate scenarios (RCP4.5 and RCP8.5) and then was analysed across near-term (2021–2050), mid-century (2051–2080), and late-century (2081–2100) horizons to evaluate changes in the frequency and magnitude of hydrological extremes (e.g., >10 000 m³/s and >15 000 m³/s for floods; <3 000 m³/s for low flows) and seasonality patterns relative to the historical baseline (1971-2006). Sectoral context for interpretation was drawn from ICPDR, UNECE, and national data for the Lower Danube / Brăila region. Results show that climate change amplifies hydrological variability rather than uniformly shifting mean discharge. By mid-century, the frequency of high-flow events (>10 000 m³/s) increases by ~50 – 75 %, and extreme floods (>15 000 m³/s), historically rare, become recurrent under both scenarios. Concurrently, exposure to navigation-critical low flows (<3 000 m³/s) rises substantially, with up to ~80 days per year below this threshold by the late century under RCP8.5. Seasonal reorganisations are pronounced: flood peaks shift toward winter, while critical low flows concentrate in summer and early autumn.
Interpreted through an ecosystem services and socio-economic vulnerability framework, these hydrological changes weaken regulating services (natural flood mitigation), strain supporting services (habitat integrity and resilience), and constrain provisioning services such as water for agriculture and inland navigation. The co-occurrence of altered extremes and seasonality underscores cascading risks that extend beyond physical hazard zones, affecting agricultural productivity, transport reliability, and community adaptive capacity.
How to cite: Adamescu, M., Cheval, S., Dumitrescu, A., Amihaesei, V., Giuca, R., Racoviceanu, T., Craciunescu, V., Bowyer, P., Cazacu, C., Danielescu, S., and Bothe, O.: Climate Change–Driven Hydrological Extremes and Indirect Impacts on Socio-Economic Vulnerability and Resilience in the Danube Basin, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-18747, https://doi.org/10.5194/egusphere-egu26-18747, 2026.
The Danube River Basin, spanning 19 countries and covering approximately 801,000 km², is an important agricultural region in Europe and exhibits strong spatial contrasts in water availability and use. Crop production in the basin depends on both rainfed and irrigated agriculture, with pronounced spatial diversity in crop composition, climate conditions, and water availability. Irrigation plays a critical role particularly in downstream areas, with many countries having plans or incentives to expand irrigated agriculture due to increasing drought risk under climate change. At the same time, increasing irrigation water demands may exacerbate water scarcity, alter river flow regimes, and intensify pressures on aquatic ecosystems, highlighting the need for a coordinated, basin-wide and adaptive future agricultural water management.
Building on the concept of Safe Operating Space (SOS), which aims to define sustainable limits for human pressures on Earth system processes, the Horizon Europe SOS-Water project seeks to operationalize the SOS for water resources under changing climatic and societal conditions. Within SOS-Water, agricultural water use is a key component of the coupled human–water system and is analysed using integrated modeling and stakeholders-informed future scenarios.
This proposed talk will present the application of the SOS framework in the Danube Basin, with a focus on spatially explicit crop modelling and future irrigation scenarios. Using the Community Water Model (CWatM), we simulate crop-specific water demands, seasonal dynamics, and irrigation scenarios consistent with Shared Socio-economic Pathways (SSP1-2.6, SSP3-7.0, SSP5-8.5), allowing the evaluation of irrigation expansion and efficiency improvements across the upper, middle, and lower Danube sub-basins.
The analysis will explore how crop dynamics and alternative irrigation pathways influence water demand and water availability in the Danube basin, and illustrate how the SOS approach can be used to support the assessment of sustainable water management options in transboundary regions.
How to cite: Artuso, S., Politti, E., Burek, P., Tramberend, S., Smilovic, M., and Kahil, T.: Crop Water Use and Future Irrigation Scenarios within a Safe Operating Space Framework in the Danube Basin, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-13157, https://doi.org/10.5194/egusphere-egu26-13157, 2026.
Climate change impact studies often use large and complex climate scenario datasets. However, these datasets are not always easily accessible or usable, especially for non-specialist users. To address address this challenge, the Restore4Life wetland Restoration Decision Support System was developed as an online interactive platform enabling users to easily explore and visualize climate change scenarios based on CMIP6 simulations over the Danube River Basin. The platform integrates bias-corrected climate projections based on simulations from eight global climate models and an ensemble approach is applied, using the median as the central estimate and the 10th and 90th percentiles to represent model uncertainty. Users can interactively explore spatial patterns, temporal horizons, variables, and scenarios through a web-based interface, supporting both scientific analysis and climate services applications. The platform provides climate change signals for air temperature and precipitation, and several related extreme indices. Four Shared Socioeconomic Pathways are included: SSP1, SSP2, SSP3, and SSP5, covering a wide range of possible future developments.
To ensure transparency, reproducibility, and long-term accessibility, all processed datasets used on the platform are published in a standardized format and openly available through the Zenodo repository, with persistent identifiers. A key feature of the application is the interactive spatial analysis capability. The application allows analysis for several predefined areas of interest, including vulnerable ecosystems. In addition, users can draw their own areas of interest directly on the map. This enables location-specific analyses adapted to different user needs. The platform was developed using the Shiny framework and is deployed on a state-of-the-art IT infrastructure. Beyond the interactive web interface, this infrastructure provides programmatic access to all underlying datasets through standardized, cloud-optimized protocols and formats, including OGC WMS/WCS, OGC API services, STAC, Zarr, Cloud Optimized GeoTIFF (COG) and GeoParquet.
Acknowledgment
This research was funded by the "RestoreForLife (Restoration of wetland complexes as life supporting systems in the Danube Basin)" project, under the European Union’s Horizon Europe Programme (Grant agreement No. 101112736).
How to cite: Amihăesei, V., Cheval, S., Crăciunescu, V., Micu, D., Adamescu, M., and Dumitrescu, A.: An online platform for exploring the climate change impact on ecosystems and wetland restoration potential in the Danube River Basin, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-13786, https://doi.org/10.5194/egusphere-egu26-13786, 2026.
The Danube River Basin is one of the most complex hydrological systems in the world, collecting waters from 19 countries and covering an area of over 800,000 km². In the context of ongoing climate change, the Danube River faces increasing challenges in achieving effective water resource management.
Projected hydrological changes and trends in the Lower Danube River Basin were assessed using simulated river discharge for 1985–2100, forced by downscaled and bias-corrected meteorological inputs derived from 11 General Circulation Models (GCMs) within the ISIMIP3b (5 models) and RESTORE4LIFE (6 models) datasets. The reference period was selected as 1985–2014, consistent with the CMIP6 historical simulations. The projected periods are 2031–2060 (mid-century) and 2071–2100 (late-century), simulated using the CMIP6 climate change scenarios SSP2–4.5 (Middle of the Road) and SSP5-8.5 (Fossil-fuelled development). Within the framework of the Danube Water Balance project, a hydrological water balance model is being developed for the entire Danube River Basin, using the Community Water Model (CWatM), which was specifically configured, calibrated, and validated for this basin.
This study focuses on the major tributaries draining Romanian territory that contribute to the flow regime of the Lower Danube River. The results indicate significant changes and decreasing trends in discharges of the analysed rivers, particularly under SSP5–8.5. Under SSP2–4.5, generally a stationary trendline has been highlighted. However, inter-model spread across the 11 GCMs combined with the SSP–RCP scenarios contributes to notable uncertainty in the projections. Additionally, significant differences are observed among the analysed river basins regarding how future discharge will evolve.
Understanding how river discharge may evolve in the future could support the timely implementation of measures and policies for the sustainable management of the analysed Danube tributaries and the Lower Danube River as a whole.
Acknowledgment
This work/paper was supported as part of DANUBE WATER BALANCE – DRP0200156, an Interreg Danube Region Programme project co-funded by the European Union.
How to cite: Radu, A., Burek, P., Mătreață, M., and Chendeș, V.: Projected Hydrological Changes and Trends in the Romanian district of the Lower Danube River Basin under Climate Change, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-20479, https://doi.org/10.5194/egusphere-egu26-20479, 2026.
Projected climate change in the Danube River Basin (DRB) indicates significant shifts in temperature, precipitation patterns, and hydrological cycles, with pronounced spatial and seasonal variability. Among these impacts, drought risk is projected to escalate dramatically, particularly in the southern and eastern DRB (e.g., Romania, Bulgaria, Serbia), due to synergistic effects of reduced summer precipitation, higher temperatures, and increased evapotranspiration. Existing studies, however, focus on single sub-regions of the DRB or rely on a limited number of Global Circulation Models (GCMs) and Representative Concentration Pathways (RCPs).
This study encompasses the entire DRB, divided into its Upper, Middle, and Lower sub-basins, and examines the projected evolution of meteorological drought characteristics under three RCPs, targeting the joint probability of drought duration and severity using a multivariate Copula-based framework and the Standardized Precipitation Evapotranspiration Index (SPEI) months to model the dependence structure between drought variables.
The workflow consisted of two stages: validation and projection. Initially, historical simulations from five GCMs under three RCPs were validated against the Climate Research Unit (CRU) observational dataset. The Kolmogorov-Smirnov (KS) test confirmed that all selected GCM-RCP datasets reliably reproduced the empirical cumulative distribution functions of historical drought duration and severity.
In the second stage, we contrasted a Pooled Ensemble Analysis—where all GCM events were aggregated to fit a single Copula—with a Per-GCM Analysis. The latter fitted separate Copulas for each model and used model-specific thresholds to define historical extremes. By anchoring the definition of a "100-year event" to each GCM’s historical climatology rather than a universal baseline, this method normalised inherent model biases (e.g., "wetter" vs. "drier" base states), allowing for a more accurate assessment of relative change and internal climatological shifts.
Results from the Ensemble analysis indicate a clearer signal of intensification, particularly for extreme events under high-emission scenarios (RCP 8.5). For example, historical 100-year events are projected to occur every 37 years in the Middle sub-basin and every 13 years in the Upper sub-basin. Furthermore, an analysis of "Risk Multipliers" reveals that extreme events are disproportionately affected compared to moderate events; the rarest droughts of the past are those projected to see the most dramatic increase in frequency.
However, the Per-GCM analysis exposes significant inter-model variability that the ensemble average obscures. When analysed against their own baselines, individual GCM trajectories diverge: while some models (e.g., GFDL-ESM4) depict a doubling of drought frequency, others (e.g., MRI-ESM2-0) project stability or even a decrease in frequency (wetting). This "fanning out" of projections highlights that, while the aggregate consensus points towards drying, the specific magnitude of local change remains subject to structural model uncertainty. Consequently, adaptation strategies must look beyond ensemble means and account for this wide range of plausible hydrometeorological futures.
How to cite: Politti, E., Burek, P., Catania, C., Artuso, S., and Kahil, T.: Multivariate Drought Risk Evolution in the Danube River Basin: A Copula-Based Analysis of Duration and Severity Across Sub-Basins, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-4761, https://doi.org/10.5194/egusphere-egu26-4761, 2026.
This study quantitatively assesses the potential impacts of the Qosh Tepa Canal (QTC) construction and water diversion from the Amu Darya River on water availability, irrigated land, and farmer employment in Kashkadarya Province, Uzbekistan. Using a proportional impact assessment framework and scenario analysis, the research projects a progressive reduction in annual water availability by over 1.2 billion cubic meters (BCM) by 2030 under a 20% diversion scenario. This water scarcity is estimated to reduce irrigated land per farmer by approximately 19% and decrease farmer employment by up to 24% by 2030. The findings highlight critical challenges for the province’s irrigation-dependent agriculture, particularly for high-water-demand crops such as cotton and wheat, and underscore the broader socio-economic risks including rural livelihood destabilization and potential forced migration. The study emphasizes the urgent need for adaptive water management policies, crop diversification, and rural livelihood support to mitigate adverse effects on the water-food-livelihood nexus in the region.
How to cite: Bamgboye, T. T., Baubekova, A., and Torabi Haghighi, A.: Impacts of the Qosh Tepa Canal on Water Availability, Irrigated Land, and Farmer Employment in Kashkadarya Province, Uzbekistan: Implications for the Water–Food–Livelihood Nexus, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-618, https://doi.org/10.5194/egusphere-egu26-618, 2026.
The Amu Darya Basin, with an estimated flow rate of 2,525 cubic meters per second, has long played a key role in supporting large-scale agriculture and economic development in Central Asia, particularly in downstream countries such as Turkmenistan and Uzbekistan. Due to the prolonged conflict, instability, institutional incompetency and exclusion from basin-wide water management provisions during the Soviet period, Afghanistan has been unable to utilize the basin’s water resources for decades, despite of being a major upstream riparian in the region. Consequently, extensive asymmetries have arisen in the distribution of development benefits resulting from the Amu Darya.
Turkmenistan annually diverts more than 13 km³ of water from the Amu Darya through the Karakum Canal, supporting wheat and cotton production. In contrast, upstream countries such as Afghanistan have not experienced similar infrastructure development due to prolonged conflict and institutional constraints, which has often led to imbalances in water use and development among the concerned states. By comparing the long-lasting role of the Karakum Canal in Turkmenistan with the more recent Qosh Tepa Canal initiative launched in 2022 in northern Afghanistan, this paper examines Afghanistan’s overdue engagement in water resources development within the Amu Darya basin. Though the canals are comparable from their scale and strategic prospects, however, their unlike development paths embody variances in terms of political support, financial capacity and historical opportunities in lieu of inequality in right or need for development. The Karakum Canal became a cornerstone of Turkmenistan’s agricultural economy under strong Soviet institutional backing, it transformed large arid land of the Karakum Desert into irrigated agricultural land, expanded cultivated land and increased agricultural output, the canal also supported settlement expansion and stabilized rural livelihoods, whereas Afghanistan’s internal instability and limited access to international support constrained similar investments for decades. instead of framing Afghanistan’s current water use as a disruption to existing arrangements, this study emphasize on a cooperation-oriented perspective that situates the Qosh Tepa Canal as a long-overdue corrective to historical imbalance.
The paper highlights that an inclusive governance mechanism is required for the sustainable water management of the Amu Darya basin that identifies both the real development need of Afghanistan and to address the concerns of other downstream countries through negotiation, efficiency improvements and cooperation. It suggests equitable and cooperative methods and approaches that offer a logical and realistic way to ensure regional water security, economic resilience and long-term stability in Central Asia, particularly among the riparian countries.
How to cite: Hamdard, M. H. and Gohari, A.: Equity and Cooperation in the Amu Darya Basin: Afghanistan’s Delayed Path to Water Development from Karakum to Qosh Tepa: Historical Asymmetry and Cooperative Adjustment in the Amu Darya Basin., EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-5464, https://doi.org/10.5194/egusphere-egu26-5464, 2026.
Mountainous regions contribute disproportionately to streamflow, particularly in arid regions such as Central Asia, and may be more susceptible to climate change with implications for downstream water resource development. The Kashkadarya is a regionally important river located in the Republic of Uzbekistan and within the Amu Darya watershed. The hydrology of the Kashkadarya is dominated by snowmelt generated from the headwaters in the western Pamir-Alai Mountains. The watershed has an elevation range of 404 m to 4,332 m and is data-scarce, particularly at high elevations, with only three of eight weather stations in the watershed above 2,000 m and no weather stations above 2,700 m. This investigation presents a case study to understand trends and predictability in snow-water resources in the Kashkadarya watershed above Qarshi, Uzbekistan (11,344 km2). We developed a high-resolution (100 m), long-term (1950–2023, 73 water years) snow water equivalent (SWE) dataset using a physics-based snow model (SnowModel) forced with the ERA5-Land meteorology reanalysis. To improve the SnowModel simulation, local station-derived air temperature and precipitation lapse rates were used with a spatial precipitation correction grid. The spatial precipitation correction grid was generated by comparing snow persistence, the long-term average of percent snow covered days from January 1 – July 1, from an initial SnowModel simulation to observed MODIS cloud-gap-filled snow persistence. These modifications in the model improved mean Kling–Gupta Efficiency (KGE) of simulated and observed SWE time series at the three high-elevation weather stations from 0.44 (default model configuration) to 0.64 (model configuration with local lapse rates and precipitation grid correction). Watershed wide nonparametric Mann–Kendall trends in annual peak SWE amount and timing were not present; however, some decreasing mean peak SWE trends were present in 200 m elevation bands between 1,100–1,500 m (mean Sen’s slope = -0.35 cm/decade, mean p-value < 0.05). Peak SWE timing trends illustrates broader changes in the watershed with earlier mean day of water year of peak SWE from 1,300–2,900 m and 3,100–3,500 m (mean Sen’s slope = -1.62 days/decade, mean p-value < 0.05). To understand the predictability of the mountain snowpack in the watershed, first of the month mean SWE values for each elevation band will be compared to teleconnection indices (e.g., the Pacific Decadal Oscillation) and other variables (e.g., preceding precipitation and air temperature) as well as streamflow measurements in the watershed. These results suggest that while the volume of snow water resources remain stable in the high elevations of the watershed, the timing of snowmelt is shifting in the mid- to high-elevation portions of the watershed, portending changes to the melt dynamics in the most hydrologically productive areas of the watershed.
How to cite: Barnhart, T., Umirzakov, G., Gafurov, A., Yarashev, D., Crowley-Ornelas, E., Steeves, P., and Asquith, W.: Elevation-dependent trends in peak snowpack amount and timing illustrate emerging snow water resource changes: a case study from the Kashkadarya River, Uzbekistan, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-2160, https://doi.org/10.5194/egusphere-egu26-2160, 2026.
Southwest Kyrgyzstan is one of the most socioeconomically disadvantaged and environmentally sensitive regions of the country, characterized by water scarcity, aging irrigation infrastructure, land degradation, and increasing climate change impacts. These problems have been compounded by transboundary water disputes with Uzbekistan and Tajikistan in the Fergana valley. Springs occur across southwest Kyrgyzstan, particularly in karstified limestone, but information on their hydrology and utilization as water resources is lacking. During 2025, we measured field water-quality parameters (pH, electrical conductivity, temperature, dissolved O2, turbidity) at 54 springs, primarily in Batken province. We sampled 23 springs for analyses of metals, anions, nutrients, and stable isotopes of water (δ2H and δ¹⁸O), and we deployed pressure and temperature loggers at 3 springs. We assessed local water use through a random sampling household survey with 154 respondents and semi-structured key informant interviews. Chemical quality of the studied springs is generally good. Solute concentrations were less than WHO guidelines in all but 2 instances (NO3 at one spring and Ba at another, neither of which was used for drinking water). The 5 springs with total dissolved solids (TDS; calculated from solute analyses) > 750 mg/L had SO4 as the dominant anion. Of the other 18 springs sampled, 15 had Ca-HCO3 or Ca-Mg-HCO3 facies. Major-ion chemistry appears to reflect dissolution of carbonate and evaporite minerals, cation exchange, and partial evaporation. Most spring waters fall close to the Global Meteoric Water Line on an δ2H–δ¹⁸O plot, indicating a meteoric origin. Springs with TDS < 450 mg/L show a slope of 5.7, suggesting partial evaporation prior to recharge, while waters with higher TDS exhibit a weak δ²H–δ¹⁸O relationship, implying mixing processes and prolonged water–rock interaction. The δ¹⁸O values show a weak but discernible altitude effect, whereas spring water temperature exhibits a stronger negative correlation with elevation. Springs are used for drinking/domestic supply, irrigation, livestock watering, aquaculture, and recreation. Of survey respondents, 42% rely on piped systems, 37% on irrigation channels, and 29% on springs. Respondents reported variable water quality, including salinity, turbidity, color changes, and occasional odors. Most respondents (95%) reported no occurrence of infectious diseases among household members. Respondents demonstrated high awareness of climate-related risks, including drought (54%) and increasing temperatures (61%). Overall, 40% of respondents reported declining water availability, and 18% indicated that irrigation water no longer reaches their fields. Survey findings highlight the need for integrated interventions, including protection and monitoring of springs, household-level water treatment and safe storage, rehabilitation of irrigation infrastructure, and promotion of water-saving technologies. Implementing these measures can improve water security, agricultural productivity, and rural livelihoods while strengthening climate resilience in Batken province. Pending work includes compiling logged water-level and temperature data during the next year in conjunction with meteorological data. Study results and recommendations for spring utilization will be shared with local stakeholders (e.g., community members and representatives of water-users associations) and Kyrgyz government agencies.
How to cite: Fryar, A., Orunbaev, S., Jalilova, G., Asanov, B., and Rignall, K.: Assessment of Springs as Rural Water Resources in Southwest Kyrgyzstan, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-22543, https://doi.org/10.5194/egusphere-egu26-22543, 2026.
The importance of digitalization in agriculture has been steadily growing worldwide, particularly under the conditions of climate change and resource scarcity. Despite the widespread adoption of digital technologies and digital services in agricultural production, there is still limited real-time data-based evidence on the effectiveness of digital irrigation system in the global literature. To address this gap, this study aims to provide comprehensive insights into technical background, experimental methodology, and the key findings of a case study implemented in the Zarafshan River Basin, Uzbekistan. The study systematically assesses the performance of climate-responsive irrigation scheduling by examining multiple dimensions of agricultural productivity and resource-use efficiency under field conditions. More specifically, water savings, total crop productivity and crop water productivity indicators are evaluated across the four distinct treatments. The findings of the study highlight not only the efficiency gains achieved through digital irrigation advisory systems, but also the practical trade-offs between maximizing yield and minimizing water consumption under conditions of increasing water scarcity and climate change in the country.
How to cite: Babakholov, S.: The importance of digital irrigation advisory system: evidence from Zarafshan River Basin, Uzbekistan, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-6901, https://doi.org/10.5194/egusphere-egu26-6901, 2026.
Transboundary water systems under increasing water scarcity are often characterized by limited monitoring capacity and restricted data sharing, particularly in regions affected by political tensions or conflict. These limitations severely constrain the assessment of basin-wide hydrological conditions and informed water management. The Surface Water and Ocean Topography (SWOT) mission offers a step change in this context by enabling consistent, independent observations of inland surface waters across national boundaries.
SWOT provides near-global measurements of water surface elevation, river width, river slope, lake and reservoir area, and their temporal dynamics at sub-monthly sampling. Through these observations, SWOT enables the estimation of variables that have historically been poorly monitored from space, including river discharge, lake and reservoir inflow and outflow, and changes in surface water storage. This multi-variable capability is particularly valuable in transboundary basins where in-situ data are sparse, inaccessible, or politically sensitive, and where monitoring needs extend beyond rivers to lakes and reservoirs that regulate downstream flows.
As a demonstration, we highlight applications in the Amu Darya basin, one of the most critical yet least transparent river systems in Central Asia. The basin exemplifies a setting where upstream regulation, poorly monitored tributary inflows, and downstream irrigation withdrawals strongly shape the water balance, while reliable hydrological data remain limited. By combining SWOT-derived river width, water surface elevation, and surface water extent, we show how basin-scale water balance components can be inferred without reliance on shared in-situ observations. This includes diagnosing upstream regulation signals, quantifying inflows from ungauged tributaries, assessing downstream irrigation diversions, and resolving the dynamics of lake and reservoir inflow and outflow. In this way, SWOT effectively functions as an independent hydrological observing system, enabling physically consistent assessments of water availability and use across political boundaries and providing a robust evidence base for scientific analysis and dialogue in transboundary basins under increasing water scarcity.
How to cite: Tourian, M. J., Ettehadieh, S., Yu, S., Saemian, P., Ke, S., Khalili, S., Kitambo, B., Elmi, O., and AghaKouchak, A.: Monitoring transboundary water systems from space: SWOT opportunities for data-scarce and politically sensitive basins, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-11710, https://doi.org/10.5194/egusphere-egu26-11710, 2026.
The Middle East is situated in the desert belt of the Northern Hemisphere, where the average annual rainfall is just one-third of the global average, and evapotranspiration rates are three times higher than the global average. The average renewable water resources in the region are approximately 1,200 cubic meters per person per year, compared to the global average of around 7,000 cubic meters per person per year.
The region is experiencing one of the highest population growth rates, which has increased the demand for water resources. The area faces both physical and economic water scarcity, aggravated by mismanagement and climate change, which further strain water resources. Most climate change studies predict a drier climate for the Middle East over the next century, with reductions in precipitation of 20-30% and increases in temperature of up to 4° C, leading to less water availability for an ever-growing population.
Using regional case studies and cross-sectoral analysis, this study demonstrates how the interaction between climate variability and anthropogenic mismanagement has already resulted in environmental degradation, including accelerated groundwater depletion, widespread land subsidence, progressive soil and land degradation, shrinking surface water bodies, and a marked increase in dust storm frequency and intensity. Importantly, these impacts propagate beyond national borders, creating transboundary environmental hazards that affect regional stability, food security, and public health. The results highlight shared vulnerability hotspots and reveal common drivers across river basins and aquifer systems. Based on these findings, the study evaluates targeted adaptation scenarios, emphasizing improved groundwater governance, land and dust storm detection and mitigation, and coordinated transboundary water management as priority pathways to enhance regional resilience under a changing climate.
How to cite: Hashemi, H.: The Middle East’s Triple Treat: Drought, Dust, and Sinking Lands, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-12100, https://doi.org/10.5194/egusphere-egu26-12100, 2026.
Water security across Central Asia is increasingly threatened by climate variability, ageing irrigation infrastructure, rapid demographic change, and complex transboundary water-sharing arrangements. Digitalisation combined with advanced Earth Observation (EO) technologies provides a critical pathway for improving transparency, strengthening regional cooperation, and supporting sustainable basin-scale water management. In this study, we demonstrate an integrated digital–EO framework for monitoring water availability and evaluating hydrological dynamics across the Syr Darya and Amu Darya basins. Using multi-source datasets—including CHIRPS and GPM precipitation, MODIS and SSEBop evapotranspiration, and GRACE/GRACE-FO total water storage anomalies—processed within the Google Earth Engine environment, we quantify seasonal and interannual variability in catchment-scale water balance components. The analysis highlights significant hydrological fluctuations driven by climate and upstream water-use pressures, underscoring the need for adaptive and data-driven management approaches.
We further discuss how the combination of remote sensing, machine learning analytics, and emerging IoT-based monitoring systems can enhance the digital transformation of water governance in Central Asia. These tools support more equitable data sharing, reduce uncertainty in transboundary negotiations, and provide a technical foundation for strengthening water diplomacy between riparian states. The study concludes with recommendations on operationalising EO‑based digital platforms to improve transparency, build trust, and advance long-term water security and cooperative river-basin governance in the region.
How to cite: Jarihani, B., Salokhiddinov, A., Brody, M., Umirzakov, G., Turgunov, D., and Rakhmonov, K.: Digitalisation and Earth Observation for Sustainable Water Security and Transboundary Diplomacy in Central Asia, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-22296, https://doi.org/10.5194/egusphere-egu26-22296, 2026.
According to the UN Valuing Water Initiative, accurate measurement of water resources is critical to valuation, decision making, and governance. Rotary drilling and submersible pump technologies, which proliferated in the 1950s-1970s, facilitated rapid and widespread development of global groundwater reserves. Currently, 25% of global water use is from groundwater, trending towards 100% in arid regions, and 75% of this groundwater is used for agriculture. Because it is difficult to measure, regulation of groundwater use is sparse and underenforced, and international treaties governing use of groundwater are virtually non-existent. Given the promise of spatial ubiquity in satellite observations, the hydrologic remote sensing research community has made tremendous progress in the measurement of hydrologic fluxes that are aliased by sparse in-situ networks. Two promising data derivatives—mainly energy-balance actual evapotranspiration derived from radiometric surface temperature and surface displacement associated with groundwater extraction from interferometric synthetic aperture radar—have fundamentally changed our understanding of how anthropogenic groundwater use in particular is modifying the hydrosphere, and enable estimates of relative groundwater extraction rates at the well/farm scale. Due to the high computational costs and technical complexity associated with processing these datasets, particularly at the spatial scales required for national to transboundary water accounting, their use in operational water management has been limited.
Two operational datasets published in the United States this year allow for both large and small-scale accounting of agricultural groundwater use: the OpenET project DisALEXI dataset, and the OPERA project’s Sentinel 1 interferometric LOS displacement dataset. We demonstrate how independent error sources in these two datasets assist with uncertainty characterization, and benchmark their performance against GRACE observations of total water storage flux. We demonstrate how they allow us to estimate both regional (aquifer to nation-level) and local (field and well-level) groundwater use. We focus our analysis on 34 aquifers that span the United States/Mexico border, where a deepening water crisis is playing out in the absence of international agreements on transboundary aquifer use. We use this case study to demonstrate how investment in production of Level-3 datasets from entire satellite archives can enable international collaboration on natural resource development.
How to cite: Carter, E., Caldwell, C., Yang, Y., Kennedy, J., Schnabel, C., Srikrishnan, V., Hain, C., and Anderson, M.: New Level-3 datasets demonstrate that robust field-level groundwater use accounting is possible at continental scales: what is next for transboundary aquifer governance?, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-16786, https://doi.org/10.5194/egusphere-egu26-16786, 2026.
The Caspian Sea is the largest enclosed water body on Earth, and it is undergoing rapid fluctuations in water level that pose significant risks to ecosystems, infrastructure, and socio‑economic activities across its littoral states. This study integrates hydrological and atmospheric perspectives to identify the primary drivers of recent and projected sea level changes.
Long‑term hydrological records (1938–2020) from the Volga River, the dominant freshwater contributor, reveal a strong historical correlation between high runoff and increased atmospheric precipitation in its basin. However, since 2005, a marked decline in the runoff coefficient at the Verkhneye Lebyazhie hydrological station has been observed, attributable to regional warming that exceeds global temperature anomalies. This decline contributed to a 133 cm reduction in Caspian Sea level between 1977 and 2020. Importantly, while sea level changes historically mirrored Volga runoff fluctuations, since 2006 the relationship has decoupled, suggesting additional climatic drivers beyond river inflow.
To investigate these drivers, wind regime variability was analysed using Modern‑Era Retrospective analysis for Research and Applications, Version 2 (MERRA‑2) reanalysis data spanning 1980–2023. Statistical tests revealed no significant differences in average wind speed between the phase of sea level rise (1984–2004) and decline (2005–2022). However, the resultant wind speed increased by 10.3%, accompanied by a 9.5° shift in the predominant direction, indicating a reorganisation of atmospheric circulation over the basin. Comparison with the Southern Oscillation Index (SOI) and North Atlantic Oscillation (NAO) demonstrated moderate correlations, underscoring the role of global teleconnections in shaping evaporation and water balance dynamics.
As a broader context, near‑surface air temperature across the Caspian region increased by ~1.3 ± 0.5 °C since the mid‑20th century, with ERA5 showing stronger warming in the north (~1.6 °C) and peaks up to 3.0 °C in Iran’s mountainous areas. This regional warming amplifies evaporation and interacts with wind regime changes, further accelerating sea level decline.
These findings highlight that Caspian Sea level dynamics cannot be explained by river runoff alone, but are mediated through atmospheric circulation shifts and regional climate variability. By integrating hydrological records, wind regime analysis, and climate context, this study advances the scientific basis for forecasting and adaptation strategies. The results emphasise the need for coordinated climate‑hydrology assessments to anticipate future risks in the Caspian basin, where natural variability interacts with anthropogenic pressures.
How to cite: Safarov, E. and Safarov, S.: Drivers of Caspian Sea Level Decline: Volga Runoff, Wind Regime, and Climate Variability, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-840, https://doi.org/10.5194/egusphere-egu26-840, 2026.
Water in the Middle East transcends its role as a natural resource, underpinning state sovereignty, regional power, and national security. Climate change is intensifying droughts, altering precipitation, and amplifying extremes, pushing limited water resources toward crisis. This study examines how geopolitical influence increasingly aligns with the flow of rivers rather than political borders. Integrating climate variables such as temperature, precipitation, snow mass and runoff derived from CMIP6 projections (1980–2100; SSP2–4.5 and SSP5–8.5 scenarios) and ERA5 reanalysis, alongside governance indicators, water management frameworks, transboundary agreements, and scenario-based policy analysis, the study explores how climatic and institutional factors jointly shape regional resilience. In this study, we compare future climate conditions to a baseline period (1980–2014). The future periods considered are 2021–2050, 2051–2080, and 2081–2100. The results indicate a persistent snow drought beginning in the early 2000s, marked by reduced snowpack despite normal or above-average precipitation. Rising temperatures have increasingly shifted snowfall to rainfall during the baseline period, and this trend is projected to intensify across future warming periods. This shift diminishes seasonal snow storage, the region’s key natural water reservoir, weakening spring and summer river discharge. The resulting decline in snow mass threatens irrigation, hydropower, and urban water supplies while heightening transboundary tensions. By linking physical climate modeling with governance perspectives, the study demonstrates that water management and adaptive policy responses will determine future stability and cooperation in the region. Ultimately, the findings underscore that in a warming Middle East, control over water resources and mitigation strategies not territory will define geopolitical power and resilience.
Focusing on Iran’s transboundary basins, the Helmand and Harirrud in the east, the Tigris–Euphrates in the west, and the Aras in the northwest, this study shows how climate variability, snow drought, and upstream interventions have reshaped ecological and political relations. In the Helmand Basin, upstream dam construction in Afghanistan and prolonged droughts have reduced Iran’s downstream flows to a fraction of treaty levels, desiccating the Hamun wetlands and fueling border tensions over the past two decades. In western Iran, climate change and large-scale water projects have degraded both water quality and quantity, transforming scarcity into a source of protest and instability in recent years. Similarly, industrial pollution in the Aras River has turned a formerly cooperative basin into an arena of environmental and diplomatic friction. Looking ahead, future droughts are projected to intensify hydropolitical tensions, aggravating ecological degradation, inequality, and unrest especially in border regions of the Middle East countries such as Khuzestan, Kurdistan, Sistan and Baluchestan provinces of Iran. As water insecurity deepens, two conflict pathways emerge: scarcity-driven social instability and the strategic use of water as a tool of power. The findings highlight a growing hydropolitical security complex, where hydrological interdependence, rather than territory, defines sovereignty, stability, and regional influence in a warming Middle East.
How to cite: Aydin, Y., Talebi, R., Arjomandi, P., Shokri, U., Gholizadeh, M., Shahbazi, A., and Rasouli, K.: The Hydropolitical Power in the Middle East: Understanding Sovereignty Challenges Under a Changing Climate, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-14781, https://doi.org/10.5194/egusphere-egu26-14781, 2026.
The desiccation of the Aral Sea—driven by the large-scale diversion of the Amu Darya and Syr Darya rivers for irrigated cotton production, which began during the Soviet era—remains one of the world’s most significant human-caused environmental disasters. While the hydrological, ecological, and geopolitical dimensions of the crisis are well documented, comparatively little is known about how communities that continue to live in the most degraded parts of the basin adapt, persist, and envision their futures, particularly in rural settlements. Through a mixed-methods, exploratory comparative design, we examine community-level resilience and adaptation on both sides of the former shoreline. Fieldwork was conducted in settlements surrounding the remaining bodies of water in Kazakhstan (North Aral region) and Karakalpakstan in Uzbekistan (South Aral region). This research combined structured household surveys, semi-structured interviews, and field observations. Guided by a social-ecological systems framework, we analyze how environmental change intersects with socioeconomic conditions, governance arrangements, and historical legacies to shape adaptation options.
Our results identify multiple interacting stressors and distinguish chronic pressures from episodic shocks. Across sites, decisions to remain are influenced by place attachment, limited mobility, and family and community obligations. Social capital, especially kinship networks and informal mutual aid, emerges as a key foundation of persistence; however, it is insufficient without institutional and economic support. We observe differentiated adaptation pathways across the basin. Communities in Kazakhstan report incremental improvements associated with the ecological recovery following the construction of the Kok-Aral Dike. In contrast, communities in Karakalpakstan face structural constraints that limit incremental adaptation and increase the need for transformative interventions, including livelihood diversification and inclusive governance. By documenting how resilience emerges under persistent socio-ecological stress, this study provides empirical insights for climate adaptation and water governance in arid and semi-arid regions.
How to cite: Assubayeva, A., Ibadulla, S., Kannazarova, Z., and Xenarios, S.: Resilience and Adaptation of the Communities in the Aral Sea Basin, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-16080, https://doi.org/10.5194/egusphere-egu26-16080, 2026.
The Indus River Basin (IRB) is a vital transboundary system in South Asia that sustains one of the world’s largest irrigation networks. IRB supports extensive agricultural and socio-economic activities for over 300 million people across India and Pakistan. The Indus Waters Treaty, signed in 1960 with mediation by the World Bank, established a legal framework for allocating the Indus River water between India and Pakistan. The treaty allocated the three western rivers to Pakistan and the three eastern rivers to India. It is widely regarded as a successful model for transboundary water sharing. However, the treaty was designed under mid-20th-century hydro-climatic and geopolitical conditions that differ significantly from present-day conditions. Despite substantial changes in the Indus River Basin since the treaty’s formation, there remains a limited understanding of how climate-driven shifts have altered hydrological conditions across the two countries. In this study, we examine changes in precipitation, groundwater availability, reservoir inflows, and contributions from snow and glacier melt to the total inflow. Our results reveal a persistent drying trend in the Chenab, Ravi and Sutlej basins, with more than 16% decline in precipitation, while the western basins remain largely stable. Sharp groundwater declines exceeding 10 meters in the Sutlej and Ravi basins highlight the unsustainable dependence on groundwater. We also observe a significant reduction in annual inflow to several major Indian reservoirs, indicating a shift toward greater hydroclimatic variability. Overall, declining storage trends in major Indian dams, altered inflow regimes, intensifying climatic stressors, and evolving meltwater dynamics underscore the need to re-evaluate the existing water-sharing framework to ensure long-term sustainability.
How to cite: Vegad, U. and Mishra, V.: Evolving Hydroclimate of Indus River Basin Exposes Asymmetric Transboundary Risks, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-18173, https://doi.org/10.5194/egusphere-egu26-18173, 2026.
In many transboundary river basins, shared water resources are formally regulated through water-related agreements, laws, and regulations. These institutional documents contain diverse types of water governance rules that shape strategies and opportunities for cooperation among stakeholders. Such rules may, for example, constrain water withdrawal limits, facilitate information sharing, or coordinate collective decision-making over the development and management of shared water resources. Understanding the content of these rules and their diverse functions is therefore essential for informed policy and institutional designs in transboundary water governance.
In this study, we propose a set of rule-based indicators for assessing water governance regimes, grounded in the rule concepts of the Institutional Analysis and Development (IAD) framework. By combining these indicators with the content analysis tool of the Institutional Grammar, which enables the systematic dissection of water agreements and legislation across different formats, the proposed approach is able to use institutional rules as core analytical elements for water governance analysis. This allows for the evaluation of both the level of cooperation and the distribution of water management authority within water governance systems, and ultimately, identify the water governance modes (i.e., polycentric, centralized, or decentralized) of the basins.
We demonstrate the application of this integrated approach through a comparative analysis of four interstate river basins: the Colorado River Basin and the Delaware River Basin in the United States, the Murray–Darling Basin in Australia, and the Yellow River Basin in China. The main rivers of these subnational transboundary river basins span multiple states or provinces and are governed by extensive rule systems embedded in water agreements and legislation. The results indicate that the governance regimes of the Delaware River Basin and the Murray–Darling Basin are predominantly polycentric, the Upper Colorado River Basin exhibits a hybrid regime combining centralized and polycentric characteristics, while the Yellow River Basin is characterized by a strongly centralized governance regime.
How to cite: Lai, C. H. and Zhao, J.: Rule-Based Indicators for Assessing Water Governance Modes in Transboundary River Basins, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-2489, https://doi.org/10.5194/egusphere-egu26-2489, 2026.
Inter-State water sharing in India presents a complex governance challenge, as all river basins are shared by two or more states and are increasingly stressed by population growth, economic development, and climate-induced hydrological variability. In India’s federal system, water is constitutionally assigned primarily to the states. Effective management of shared rivers therefore requires governance arrangements that balance regional autonomy with national coordination and promote cooperation among riparian states.
India’s inter-State water governance is rooted in a layered constitutional, legal, and institutional framework. The normative foundations lie in the values of justice, equality, fraternity, and unity embedded in the Constitution, which collectively shape the ethos of cooperative federalism in shared water management. These values provide an ethical basis for equitable participation, mutual trust, and national cohesion in decision-making related to inter-State rivers.
Legislative competence over water is distributed under Article 246 and the Seventh Schedule of the Constitution. States exercise authority over intra-State water resources, while the Union government is empowered under Entry 56 of the Union List to regulate and develop inter-State rivers in the public interest. This dual allocation of powers creates a structured interdependence, often described as water federalism, enabling coordination across jurisdictions but also generating institutional tensions and competing claims among basin states.
To address these tensions, specialized constitutional and statutory mechanisms have been established. Article 262 and the Inter-State River Water Disputes Act, 1956 provide a tribunal-based framework for adjudicating disputes related to the use, distribution, and control of shared river waters. Judicial support provisions under Articles 131, 136, and 143 allow limited constitutional oversight, reinforcing legal coherence and legitimacy while preserving the distinct nature of inter-State water adjudication. In parallel, the River Boards Act, 1956 envisages basin-level institutions for coordinated planning and development, reflecting early recognition of the need for integrated river basin management, even though such institutions have seen limited practical implementation.
Despite the existence of this comprehensive framework, inter-State water governance in India has largely remained adjudication-driven, with cooperative mechanisms playing a secondary role. Limited operationalization of basin-level institutions, fragmented data and information sharing, and the episodic nature of inter-State engagement have constrained the effectiveness of cooperative federalism. These limitations are further amplified under conditions of hydrological uncertainty and increasing climatic variability, which demand adaptive and forward-looking governance arrangements.
Strengthening inter-State water sharing requires a shift from predominantly adversarial dispute resolution towards continuous, basin-scale cooperation. Greater emphasis on institutionalized coordination, transparent data sharing, and adaptive planning mechanisms can enhance trust among riparian states and improve the resilience of governance systems. India’s experience offers broader insights for multi-level governance systems globally, illustrating how the alignment of constitutional values, federal competencies, and cooperative institutions is central to transforming shared rivers from sources of inter-jurisdictional conflict into foundations for sustainable and equitable water management.
How to cite: Kumar, S., Chahar, B. R., and Dhanya, C. T.: Federal Governance Frameworks and Cooperative Mechanisms for Inter-State Water Sharing in India, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-21881, https://doi.org/10.5194/egusphere-egu26-21881, 2026.
Posters on site: Tue, 5 May, 08:30–10:15 | Hall A
Lakes are essential for ecological integrity, water supply, hydropower production, and recreation, yet they are increasingly threatened by the combined impacts of human activities and climate change. Urbanization and agriculture intensify nutrient loading, while rising temperatures accelerate biogeochemical processes that promote harmful algal blooms. At the same time, the increasing frequency and intensity of extreme precipitation events elevate the risk of flooding, posing serious threats to lakeshore communities and infrastructure. Transboundary lakes are particularly vulnerable to these compounded pressures, as their management is often fragmented across political boundaries with differing priorities, regulations, and data availability. Addressing these challenges requires integrated, forward-looking tools capable of representing both natural processes and human interventions. This study develops an integrated modeling framework that couples water quantity, water quality, and management practices to support sustainable lake management under current and future climate conditions. We focus on Lake Memphremagog (102 km²), a transboundary lake shared between Canada and the United States, which exemplifies these challenges. Using a multi-model approach, we simulate lake volume to characterize current hydrological conditions and associated uncertainties. Preliminary analyses reveal strong variability and emerging trends in hydroclimatic, hydrological, and thermal datasets. This study provides a solid foundation for impact assessments and provide a critical step toward management of transboundary lakes under changing conditions.
How to cite: Hassanzadeh, E. and Lisak, D.: An Integrated Modeling Approach for Managing Transboundary Lakes, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-14271, https://doi.org/10.5194/egusphere-egu26-14271, 2026.
Runoff generation in the Upper Danube Basin upstream of Vienna, which can be regarded as the water tower of the Danube region, is characterized by complex interactions of glacier, snow and rainfall-driven processes. Previous studies have shown the high sensitivity of the basin’s runoff regime to climatic changes. The presented contribution is the first climate change impact study for the Upper Danube applying latest-generation CMIP6 climate model projections.
Precipitation-runoff simulations were performed with a daily hydrological model calibrated with exceptionally long observation data series (1870-2023) that allowed comprehensive evaluation of the ability to adequately simulate the basin’s hydrology under different weather and climate conditions. Climate model data for the emission scenarios SSP2-4.5 and SSP5-8.5 were bias corrected with the Scaled Distribution Mapping method. Climate change projections were analysed to inform a physical climate storylines classification based on the projected development of large-scale climatic features (jet latitude and jet speed) in the different models of the CMIP6 ensemble.
Application of the climate projections in the hydrological model yielded long-term hydrological projections for the entire 21st century. Simulated changes in the hydrological regime are presented, with a focus on low flow discharge due to its importance for river navigation. Differences to climate impact simulations with previous climate model generations are analysed, and the potential of jet-based storylines to explain the uncertainty in hydrological projections is explored.
How to cite: Stanzel, P., Kling, H., Lerche, F., Weis, V., and Ossó, A.: Projections of Upper Danube River discharge applying the CMIP6 climate model ensemble and a physical storyline classification, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-14487, https://doi.org/10.5194/egusphere-egu26-14487, 2026.
Glacial lakes formed during glacier retreat temporarily preserve meltwater and mitigate water resource pressure, dependent on ice reserves. However, this effect is transient, and regions relying on glacial meltwater may face future water scarcity. Due to the unique characteristics of maritime glaciers, glaciers in southeastern Tibet are experiencing the most significant mass loss on Earth—approximately three times the average rate across the Tibetan Plateau—exerting profound impacts on regional water resources. Understanding glacial lake evolution and mass balance in this region is therefore critical for developing early warning systems, mitigating glacial lake outburst flood risks, and safeguarding water resources.
Existing glacial lake studies primarily focus on monitoring area changes, while direct depth and volume observations remain extremely scarce due to challenging field conditions. Traditional empirical area-volume formulas inadequately capture morphological, topographic, and hydrological variations across lake types, resulting in significant estimation errors. Although ICESat-2 possesses shallow-water bathymetry capabilities, its application faces challenges, including limited single-beam coverage, significant basin information gaps, and constraints imposed by beam spacing, cloud cover, and variable turbidity.
This study systematically integrates ICESat-2 single-beam photon data with multi-source remote sensing and topographic-meteorological data, proposing a comprehensive framework progressing from "single laser profiles" to "three-dimensional basin reconstruction" and ultimately to "regional-scale glacial lake volume estimation." Based on ICESat-2 ATL03 geolocated photon data, we established a rigorous filtering workflow that combines quality flags, confidence constraints, and interactive manual selection to eliminate noise while retaining reliable bathymetric information. We developed a novel three-dimensional basin reconstruction model that optimizes bathymetry point distribution via mirror symmetry and contour-shrinkage mechanisms, with quadratic spline interpolation constraining the deepest point and radial basis functions enabling continuous terrain reconstruction.
Model validation using unmanned boat sonar measurements across multiple glacial lakes demonstrates that the proposed method stably reproduces bowl-shaped topographic features, with volume reconstruction errors generally below 10% and only 2% variation across different lake-bottom center assumptions, confirming robustness under complex observational conditions.
By integrating in-situ observations with ICESat-2 reconstructions, we constructed a high-quality dataset of 611 samples that incorporates lake morphology, topography, hydrology, and meteorology. Using Isolation Forest filtering and the XGBoost algorithm with optimized hyperparameters and recursive feature elimination, the model significantly outperforms traditional empirical formulas, achieving an R² of 0.911 for small and medium-small glacial lakes. SHAP analysis revealed lake area as the most critical variable, with lakeshore slope, shape regularity, and regional precipitation exerting significant regulatory effects. Monte Carlo uncertainty analysis demonstrates over 88% coverage of actual volumes within 95% confidence intervals with significantly lower bias than existing methods.
This study achieves a methodological breakthrough from ICESat-2 single-beam bathymetry to three-dimensional basin reconstruction, establishing a high-precision regional-scale estimation model. It provides a scalable technical framework for glacial lake hazard assessment, water resource monitoring, and the development of early warning systems in high-mountain regions.
How to cite: wu, R.: Integrating ICESat-2 Lidar and Machine Learning for High-Precision Glacial Lake Volume Estimation in Southeastern Tibet Plateau , EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-15226, https://doi.org/10.5194/egusphere-egu26-15226, 2026.
Two major transboundary river systems in the Middle East and the Caucasus, the Tigris-Euphrates and the Kura-Aras basins, originate largely in Türkiye. Although Türkiye constitutes only a limited portion of both basins, it plays a decisive role in shaping water availability across the entire systems. These dynamics have had substantial implications for downstream countries, contributing to severe water stress in the past and potentially intensifying in the future. This issue has therefore been examined using remote sensing data, given the limited availability of ground-based information on water resources and their use in both upstream and downstream basins. Monthly precipitation, temperature vegetation dryness index (TVDI), aridity index, AET/PET, soil moisture, and groundwater storage from 2003 to 2025 were employed for this purpose. The research's findings indicate that while the downstream basins have a distinct approach to water supply and use, the upstream basins follow a similar strategy. In the Kura-Aras, in addition to precipitation and available surface water, a significant portion of the water demands has been supplied by groundwater resources, which show a sharp downward trend in all four areas studied. This has caused the AET/PET index readings to be higher than 0.5 for the majority of the year. Despite a dramatic decline in CRD and soil moisture, AET/PET values in Georgia and Turkiye have not altered much since 2017. However, the rate of groundwater storage has also increased. In contrast, the Tigris-Euphrates, although the trend of groundwater storage decline in the basin’s upper reaches occurs at a much lower slope (Sen’s slope = -2.8), the cumulative rainfall deviation in the majority of years shows a severe deficit, which supports the basin's upstream reaches' regular consumption of surface water resources. However, the AET/PET ratios are less than 0.5 in most months in Iraq, especially in the Southeast, indicating extreme water stress and scarcity. After 2010, although there have been significant swings in the groundwater level, it has consistently followed a straight linear pattern. This could be the result of political issues like a civil war, a lack of infrastructure for exploitation, or a reluctance to use groundwater to make up for the amount of water needed. The findings show that there is a difference in consumption and significant water stress in the Tigris-Euphrates watershed downstream. Although the nations downstream of the Kura–Araks have relied heavily on groundwater resources to meet their water and soil moisture requirements, this could lead to future issues and conflicts.
How to cite: Ghordoyee Milan, S., Yilmaz, N., Sonmez, M. E., and Culler, E.: Evidence from remote sensing: Do the transboundary basins exhibit signs of regulated water upstream and associated dangers and stress downstream?, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-7346, https://doi.org/10.5194/egusphere-egu26-7346, 2026.
The Danube Water Balance project was launched with the objective to improve harmonized data management, to develop a joint water balance calculation methodology for the entire Danube River Basin and to foster the common acceptance of the elaborated modelling framework.
In this study, we demonstrate the advantages of the CWatM model by presenting its water balance calculation capabilities for the Tisa River Basin (TRB), the largest tributary catchment of the Danube. In addition to the standard model setup steps, a scenario evaluation will be presented for future climate change scenarios. The TRB offers several modelling challenges as it is a transboundary catchment with mountainous and lowland areas, strong groundwater influence and complex water management solutions in the alluvial plains.
Data availability posed a limitation for the study site. While global OA data on elevation, land use, soil, and meteorology was adequate, local information on water management was scattered thematically and regionally. Calibration-validation resulted in acceptable performance for river discharge (validation KGE ranging from 0.18 to 0.88 with a median of 0.64). Gridded precipitation data from seven databases were used to check model sensitivity on the biases of meteorological forcing.
Scenario analyses were performed with a two-fold focus: (i) a comprehensive climate impact assessment involving 11 climate models (ensemble) and three SSP pathways and (ii) demonstration-oriented scenarios were simulated to verify the CWatM model's capabilities to represent surface-subsurface water balance components under future climate and changing water demands. Simulations were evaluated with respect to changes in discharge characteristics as well as storage changes.
We also present the future steps planned for the project to develop the modelling framework as a suitable tool to answer water balance-related questions across the Danube Region.
This work was supported as part of DANUBE WATER BALANCE, an Interreg Danube Region Programme project co-funded by the European Union.
How to cite: György, M., Decsi, B., Ács, T., Kozma, Z., Chappon, M., and Burek, P.: Scenario Modelling of Future Water Balance in a Transboundary Basin: Potential and Limitations from the Tisa Pilot Basin within the Danube Water Balance Project, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-18757, https://doi.org/10.5194/egusphere-egu26-18757, 2026.
The confluence of the Dyje (Thaya) and Morava rivers hosts one of the largest floodplain forest complexes in the Danube basin (~15,000 ha). This area has been intensively studied over past decades, and its ecological importance was further recognised by the designation of a UNESCO Biosphere Reserve and the establishment of a protected landscape area in 2025. The vitality and resilience of the forests as a system are closely linked to water availability in the Dyje headwater catchments, as well as to water management at the Nové Mlýny reservoir system. These shallow reservoirs, located upstream, play a key role in controlled flooding and groundwater replenishment within the floodplain.
This contribution builds upon our previous research conducted across the broader Dyje RB, which identified a statistically significant decreasing trend in annual runoff and a concurrent increasing trend in actual evapotranspiration over the period 1980–2020. No significant long-term change in total annual precipitation was detected. Instead, changes in runoff were primarily attributed to rising air temperatures, altered snow accumulation and melt dynamics, and a shift in seasonal water availability. In particular, reduced snow storage and earlier snowmelt during winter, combined with increased temperatures in spring (MAM) and autumn (SON), resulted in a prolongation of the vegetation period. This extended growing season was identified as a major driver of increased evapotranspiration and, consequently, declining runoff.
To better constrain evapotranspiration as the dominant outgoing flux of the basin water balance, additional monitoring was conducted on neighbouring water bodies. A custom floating evaporimeter platform was equipped with Li-COR Li-710 infrared gas analysers, custom (Class A derived) evaporation pans, and meteorological stations. The model input meteorological variables were derived from a gridded high resolution national data set (~500 m) and accompanied with bore hole water level measurements at eight locations. Climate change scenarios were derived using the Advanced Delta Change (ADC) method, which modifies observed time series such that changes in the mean and variability correspond to those simulated by climate models. At the daily time step, ADC explicitly accounts for changes in variability, allowing extremes to evolve differently from average conditions. For precipitation, the method also corrects systematic model biases, whereas temperature is adjusted linearly, ensuring consistency in projected warming signals. A representative ensemble of global climate models (GCMs) was used to propagate climate uncertainty into hydrological projections.
A spatially distributed multimodel framework of varying complexity and process representation was developed to assess hydrological response under present and future climate conditions. Building on this framework, a numerical groundwater flow model has been developed in MODFLOW in order to get a detailed representation of hydraulic conditions and interactions between surface water and groundwater. The modeling framework is designed to allow subsequent coupling with heat transport and solute transport modules in the future, enabling comprehensive assessments of thermal dynamics and contaminant migration and their impacts on the hydrological system and associated ecosystems.
Acknowledgement: This study was supported by the DALIA project n. 101094070, under the call HORIZON-MISS-2021-OCEAN-02 funded by the European Union.
How to cite: Pavlik, P., Vizina, A., Beran, A., and Krijt, B.: Morava–Dyje floodplain forests: A comprehensive analysis of climate-driven changes in current and future water balance, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-18265, https://doi.org/10.5194/egusphere-egu26-18265, 2026.
Water-Energy-Food (WEF) nexus challenges in Central Asia are intensifying because of climate change, increasing irrigation demand, and escalating pressures in transboundary river basins. Agriculture production in the economy of Uzbekistan plays an important role in sustainable development of the nation, accounting for 25 % of the country's GDP. Although the Zarafshan river is primarily shared between Tajikistan and Uzbekistan, upstream hydropower development, seasonal flow variability, and rising temperatures are increasingly constraining water availability for agriculture in downstream regions such as Samarkand in Uzbekistan. The Samarkand region, which relies heavily on pumped irrigation for cotton and wheat production, faces acute summer water shortages and growing dependence on grid-powered and diesel base pumping systems. These challenges underscore the necessity for resilient, low-carbon irrigation energy solutions. This study introduces water-energy simulation framework to investigate the optimization of pumping capacity and reservoir storage for efficient solar PV-powered irrigation systems. Crop water requirements are estimated using the FAO Penman-Monteith method. Monthly water-energy balances are simulated for various pumping durations (6, 8, 12, 18, 24 hrs/day), reservoir capacities and pumping heads. A comparative analysis of PV and grid scenarios assesses the role of reservoir storage in mitigating solar variability, reducing required PV capacity, and determining pump sizing. In addition to the technical assessment, the study incorporates a comprehensive economic analysis including life-cycle cost (LCC), cost-benefit analysis, and environmental impact assessment based on CO2 emissions from the grid and diesel-based pumping.
The expected outcomes will identify optimal combinations of PV size, reservoir volume, and pumping discharge that minimize costs, improve energy performance, and reduce emissions. By linking system design to WEF nexus challenges in a transboundary basin, this research aims to support sustainable, energy-efficient irrigation strategies for the Samarkand region.
Keywords: Zarafshan River Basin, Transboundary water management, Water–Energy–Food Nexus, Solar-powered irrigation, Pumping–reservoir optimization, Water–energy balance, Life-cycle cost analysis, Cost–benefit ratio, CO₂ emissions, Sustainable agriculture
How to cite: Shukurov, E., Hamzehaghdam, F., Bamgboye, T., and Torabi Haghighi, A.: A Water–Energy Simulation Framework for Designing PV-Based Irrigation Supply Systems Under Transboundary Basin Constrains: The case of Samarkand, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-842, https://doi.org/10.5194/egusphere-egu26-842, 2026.
Climate warming is rapidly reshaping high-mountain environments worldwide. Negative mass balance of glaciers across most mountain regions leads to profound shifts in regional hydrology. This fact poses particular risks for Central Asia, where up to 90% of water resources originate in the mountains and support domestic, industrial, and agricultural needs across the arid lowlands. While major transboundary rivers such as the Amu Darya, Syr Darya and Irtysh have received considerable scientific attention, much less is known about the smaller rivers, such as Ulken Almaty, Kishi Almaty, and Kaskelen, that supply water to the largest city in Kazakhstan, Almaty. The rapid rise in air temperature in the Ile Alatau Mountains is accelerating glacier melt, diminishing a critical source of runoff for the studied rivers.
Therefore, understanding how climate change affects the runoff dynamics of these small but vital freshwater sources is essential for sustainable water management in southeastern Kazakhstan. Thus, this study aims to model long-term river flow dynamics considering climatic and anthropogenic factors.
The study is based on more than a century of observational records obtained from the state hydrometeorological monitoring network. Time series analysis was performed using linear regression, the parameters of which were estimated using the least squares method, and the degree of trend severity was determined by the coefficient of determination (D). Modelling was performed using the HBV conceptual semi-distributed hydrological model. The model was calibrated using the automated GAP optimization algorithm in combination with manual parameter adjustment. The quality of the modelling was assessed using the Nash–Sutcliffe efficiency (NSE), standard deviation and PBIAS criteria, and reliability was assessed by validation over an independent period.
An analysis of long-term flow dynamics since the 1920s-30s has revealed mixed trends. The Kishi Almaty experienced a steady decline in discharge, the Ulken Almaty showed an increase in flow, while the Kaskelen had a relatively stable regime without pronounced long-term trends. It is noteworthy that during the last two decades, there has been an overall increase in runoff compared to previous periods. In this regard, the period 2000-2015 was chosen for flow modelling, which allowed climate change to be taken into account and its impact to be adequately reflected in the model parameters.
HBV modelling showed high accuracy in reproducing runoff: NSE ranged from 0.80 to 0.93, PBIAS from –0.9 to –4.7%. The model correctly reproduced the key characteristics of spring-summer floods, including the start, peak, end and duration. A comparison of modelled and observed runoff volumes showed high consistency: for Ulken Almaty, 84.6 versus 82.3 million m³, for Kishi Almaty, 53.7 versus 51.9 million m³, for Kaskelen, 132 versus 127 million m³, with a ratio of 91–95%. The validation confirmed the high efficiency of the model for the Ulken Almaty and Kaskelen rivers and satisfactory efficiency for the Kishi Almaty.
The study confirms the possibility of accurately reproducing key characteristics of flow and flood levels for taking climate change into account when planning water use and managing water resources in the region.
Key words: hydrological modeling, Climate change, Water availability, Kazakhstan
How to cite: Tillakarim, T. and Baubekova, A.: Hydrological modelling and river flow dynamics of small rivers under climate change in Kazakhstan, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-917, https://doi.org/10.5194/egusphere-egu26-917, 2026.
Transboundary water negotiations are often constrained by limited quantitative understanding of how reservoir operating choices translate into sectoral gains and losses. This study presents a Pareto-based simulation–optimization framework to support negotiation-oriented decision-making by mapping operational and design-related trade-offs in multipurpose reservoir cascades. The framework integrates the WEAP water allocation model with a multi-objective particle swarm optimization (MOPSO) algorithm to explore combinations of reservoir storage targets, release policies, and hydropower capacities that jointly influence winter energy production and downstream irrigation supply reliability. Instead of identifying a single preferred strategy, the approach produces a Pareto front representing feasible compromise solutions between conflicting objectives. This methodology has been applied to the Vakhsh River, a primary tributary of the Amu Darya, where the ongoing development of the Rogun Dam has raised significant concerns about the future of agricultural water security in downstream countries. Application results show that operating strategies maximizing winter energy production reduce downstream irrigation reliability by approximately 40%, while prioritizing downstream supply leads to about a 50% reduction in winter hydropower generation. The shape of the Pareto front further reveals intermediary operating regions where moderate energy reductions yield disproportionately large improvements in downstream reliability, highlighting operational leverage points for negotiated agreements. By identifying compromise operating regions and quantifying system sensitivities, the proposed framework supports cooperative planning and evaluation of operational flexibility in regulated transboundary river systems.
How to cite: Rafipour-Langeroudi, M., Moridi, A., and Hatamkhani, A.: A Pareto-Based Simulation–Optimization Framework for Decision Support in Reservoir Cascades: A Transboundary River Basin Case Study, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-10124, https://doi.org/10.5194/egusphere-egu26-10124, 2026.
Glaciers in the Danube Basin are projected to disappear almost entirely by 2100. This study quantifies both the trajectory of glacier loss and its hydrological consequences across the basin.
The Open Global Glacier Model (OGGM) is employed, driven by downscaled and bias-corrected meteorological forcing from multiple CMIP6 General Circulation Models to simulate the evolution of 800 glaciers from the Randolph Glacier Inventory 6.0 across three SSP-RCP scenarios. Results indicate substantial glacier loss across all scenarios, with most of the glaciated area disappearing by 2060. Even under the optimistic SSP1-2.6 pathway, only a minor fraction of glacier area and volume persists through 2100.
To assess the hydrological consequences of glacier retreat, the hydrological model Community Water Model (CWatM) is used. CWatM is calibrated for the entire Danube basin at 645 discharge stations, with daily temporal and one arcminute spatial resolution, incorporating glacier runoff contributions derived from OGGM. Paired simulations are conducted with and without glacier runoff to quantify the contribution of glacier runoff to river streamflow using historical meteorological forcing (1990–2020). Additionally, an attribution analysis is performed comparing the hydrological regime under glacier runoff with that under non-glaciated conditions in presently glaciated areas.
This study reveals the spatial and temporal patterns of glacier decline and demonstrates how glacier runoff contribution and attribution evolve along the Inn, Drau, and Danube rivers from headwaters to the river mouth, providing insights into the changing water balance of the Danube.
How to cite: Burek, P.: Attribution of glacier runoff to river streamflow in the Danube Basin, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-11119, https://doi.org/10.5194/egusphere-egu26-11119, 2026.
Water has long been a strategic resource in the semi-arid landscapes of Mesopotamia, a region spanning Turkey, Syria, and Iraq, where the Tigris and Euphrates rivers form the lifeline of societies. As water scarcity intensifies due to a combination of climatic stressors and anthropogenic pressures, the governance of transboundary rivers has become critical for ensuring health, food security, and regional stability. The stakes are particularly high in this basin, where upstream–downstream asymmetries shape political relations and exacerbate vulnerabilities.
The long-standing dispute between Turkey, the upstream hegemon, and Syria, a downstream user, has deepened in the past decade with the emergence of a de facto Kurdish administration in northern and eastern Syria along Turkey’s southern border. This political reality adds complexity to water governance, intersecting with security concerns and competing narratives of resource control. Despite the centrality of water in these dynamics, empirical verification of water availability and flow remains limited. Data scarcity, driven by sparse in-situ measurements and restricted access to hydrological information, hampers assessment of scarcity and its implications for conflict and cooperation.
Against this backdrop, this study examines whether upstream reservoir dynamics at the Atatürk Dam in Turkey are reflected in storage variations at the downstream Tishrin reservoir in Syria, and whether these hydrologic changes are accompanied by detectable signals in agricultural activity. We compiled multi-year satellite-derived time series for both reservoirs and nearby agricultural zones, including reservoir surface water level, precipitation, temperature, evapotranspiration, soil moisture, and NDVI-based vegetation activity. Variables were harmonized to a common monthly scale and prepared for anomaly-based analysis to reduce seasonal confounding.
A qualitative review of the time series indicates baseline hydroclimatic contrasts between the two study regions. Precipitation, soil moisture, and baseline NDVI appear lower in the Tishrin-side agricultural area than in the Atatürk-side agricultural area, suggesting a more water-limited system and greater sensitivity to variability in water availability. These background differences provide context for downstream vulnerability but do not explain the temporal structure of reservoir storage fluctuations and associated vegetation anomalies. The reservoir and vegetation time series suggest downstream dynamics are constrained within a lower-productivity envelope, consistent with stronger exposure to moisture stress and limits in irrigation reliability.
To move from qualitative evidence to attribution, we test whether upstream and downstream reservoir dynamics are coupled once hydroclimatic controls are considered. We use time-series comparison and statistical controls to separate signals linked to reservoir operations from those attributable to regional climate variability, drawing on precipitation, temperature, evapotranspiration, and soil moisture as contextual drivers. We then investigate whether vegetation activity across surrounding agricultural areas covaries with local reservoir conditions and hydroclimatic stress, using NDVI anomalies as an integrated measure of crop response. Finally, land use/land cover trajectories will be evaluated to place short-term variability in a longer-term landscape context, with mapping consistency to ensure apparent shifts in cultivation are not conflated with classification artifacts. This integrated satellite-based framework offers a robust, adaptable basis for evaluating transboundary water-management influences on downstream storage and agricultural conditions in a politically complex setting.
How to cite: Khodaei, B., Dinc, P., and Hamza, M.: Satellite-based assessment of upstream regulation impacts on downstream reservoir dynamics and agricultural activity between the Turkey and Syria , EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-20274, https://doi.org/10.5194/egusphere-egu26-20274, 2026.
Posters virtual: Fri, 8 May, 14:00–18:00 | vPoster spot A
EGU26-4740 | ECS | Posters virtual | VPS11
Implementing Environmental Flows in Transboundary Rivers under Climate ChangeFri, 08 May, 14:15–14:18 (CEST) vPoster spot A
Rapid dam construction, rising water demand, climate change, and increasing pollution are exposing critical weaknesses in the governance of freshwater systems worldwide, particularly in shared river basins. Although environmental flows (e-flows) are widely recognised as essential for sustaining riverine ecosystems and long-term water security, their integration in transboundary water governance has remained largely symbolic, weakly enforced, and poorly adapted to climatic uncertainty. Even durable agreements in several regions prioritise volumetric allocation and procedural cooperation, offering limited mechanisms to safeguard e-flow regimes, as illustrated by treaties such as the Indus Water Treaty and the Ganga Water Sharing Treaty. This study argues that the persistent failure to operationalise transboundary e-flows in national and transboundary river basin governance frameworks reflects a deeper and systematic governance implementation gap that has not been adequately addressed in existing literature. Much of the literature examines legal provisions, economic instruments, and monitoring systems as separate domains rather than as interdependent components of operational governance. As a result, many transboundary river agreements pair legal allocation rules with flow monitoring but fail to link these to enforceable e-flow obligations or adaptive responses. To investigate this gap, the study undertook a structured comparative analysis of ten major international treaties and river basin agreements across Asia, Africa, Europe, and North America, covering both bilateral and multilateral transboundary river systems. Existing treaties were assessed to identify why most fail to deliver implementable e-flow solutions, while arrangements where elements of effective implementation exist were examined to extract transferable best practices for future transboundary water agreements. Based on the findings, the study proposes a three-tier governance framework to operationalise transboundary e-flows under climate uncertainty. The framework integrates climate-adaptive legal obligations, economic and financial mechanisms, and monitoring, reporting, and verification systems supported by remote sensing and GIS. By reframing e-flows as an implementable component of cooperative water security, this study makes both a conceptual and practical contribution to transboundary water governance, with implications for ecological resilience, conflict reduction, and long-term regional stability.
Keywords : Water demand, Climate change, River basin treaties, Ecological resilience
How to cite: Malhotra, K. B. and Nema, A. K.: Implementing Environmental Flows in Transboundary Rivers under Climate Change, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-4740, https://doi.org/10.5194/egusphere-egu26-4740, 2026.
EGU26-17089 | Posters virtual | VPS11
Remote Sensing–Based Monitoring of Lake Sarikamish Water Level DynamicsFri, 08 May, 14:18–14:21 (CEST) vPoster spot A
Lakes and associated hydrological processes are sensitive indicators of environmental change and climate variability. Variations in lake water level and storage reflect the combined effects of atmospheric forcing (precipitation, evaporation, and temperature regime) and anthropogenic interventions, including irrigation, drainage, and hydraulic infrastructure development. Continuous monitoring of lake level dynamics is therefore essential for water resources management, evaluation of regional climate impacts, and assessment of environmental risks in arid and semi-arid regions.
Central Asia has experienced pronounced hydrological transformations over recent decades as a result of climate warming, altered precipitation patterns, and intensified human water use. These changes are manifested in contrasting lake responses, ranging from the dramatic desiccation of the Aral Sea to the expansion of endorheic water bodies receiving anthropogenic inflows. Lake Sarikamish, one of the largest lowland lakes in the region, is located along the Uzbekistan–Turkmenistan border near the escarpment of the Ustyurt Plateau and represents a key example of such coupled natural–human system dynamics.
This study investigates water level variability of Lake Sarikamish over the period 2001–2024 using satellite altimetry observations from the Global Reservoirs and Lakes Monitor (G-REALM) database. The dataset, provided at a 10-day temporal resolution in NetCDF format, was processed to construct a continuous long-term time series. Short data gaps were filled using linear interpolation, a method previously shown to yield robust performance for altimetric lake level records. Descriptive statistics and trend analyses were applied to quantify intra-annual variability, interannual fluctuations, and long-term tendencies.
The minimum lake level during the observation period was recorded in February 2002 (4.23 m), while the maximum level occurred in April 2018 (8.84 m). The time series exhibits substantial interannual variability, with a standard deviation of 0.91 m. Four distinct phases of lake level evolution were identified: (i) a rapid increase during 2001–2007 at a rate of +0.56 m yr⁻¹, (ii) a short-term decline in 2008–2009 (−0.60 m yr⁻¹), (iii) a prolonged period of moderate increase during 2010–2020 (+0.15 m yr⁻¹), and (iv) a renewed decrease during 2021–2024 (−0.36 m yr⁻¹). Despite the recent downward trend, the overall period is characterized by a net positive trend of +0.16 m yr⁻¹.
The observed post-2020 decline suggests an increasing influence of regional climate change, particularly rising air temperatures and reduced effective precipitation. Continued water level lowering may have negative consequences for local ecosystems, biodiversity, and environmental stability. The results highlight the value of satellite altimetry for long-term lake monitoring and emphasize the need for integrated assessments of climatic and anthropogenic drivers of lake hydrological change in Central Asia.
How to cite: Umirzakov, G., Kalabaev, S., Gafurov, A., and Turgunov, D.: Remote Sensing–Based Monitoring of Lake Sarikamish Water Level Dynamics, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-17089, https://doi.org/10.5194/egusphere-egu26-17089, 2026.
