Orals: Fri, 8 May, 14:00–15:45 | Room 2.17
Water cycle changes, including changes in droughts, heavy precipitation and floods, count among the most impactful consequences of human-induced climate change. This includes several changes in water cycle extremes on regional scale (Seneviratne et al. 2021; Seneviratne et al., in preparation), as well as changes in global water cycle patterns (Fisch et al. in preparation). In addition, some subregional trends can also be now detected, such as in Switzerland for streamflow and soil moisture drought (Haddad et al. 2024, Hirschi et al. submitted).
This presentation will provide an overview of on-going studies and recent articles on the attribution of regional to global changes in the land water cycle, including new emerging evidence suggesting more detectable and attributable signals of changes in water cycle extremes compared to the assessment of the 6th Assessment Report of the Intergovernmental Panel on Climate Change (Seneviratne et al. 2021).
References:
Fisch, C., D.L. Schumacher, L. Gudmundsson, and S.I. Seneviratne, in preparation: Detecting an externally forced signal in observed terrestrial water storage.
Haddad, Y.Y, L. Gudmundsson, J. Savelsberg, J.B. Garrison, E. Raycheva, T. Wechsler, M. Zappa, G. Hug, and S.I. Seneviratne, 2025: Recent climate impacts on run-of-river hydropower and electricity systems planning in Switzerland. Environ. Res. Lett., 20, 084020.
Hirschi, M., D. Michel, D.L. Schumacher, W. Preimesberger and S.I. Seneviratne, in review: Recent summer soil moisture drying in Switzerland based on measurements from the SwissSMEX network. Earth System Data Discuss. [preprint], https://doi.org/10.5194/essd-2025-416, in review, 2025.
Seneviratne, S.I., X. Zhang, M. Adnan, W. Badi, C. Dereczynski, A. Di Luca, S. Ghosh, I. Iskandar, J. Kossin, S. Lewis, F. Otto, I. Pinto, M. Satoh, S.M. Vicente-Serrano, M. Wehner, and B. Zhou, 2021: Weather and Climate Extreme Events in a Changing Climate. In Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change [Masson-Delmotte, V., P. Zhai, A. Pirani, S.L. Connors, C. Péan, S. Berger, N. Caud, Y. Chen, L. Goldfarb, M.I. Gomis, M. Huang, K. Leitzell, E. Lonnoy, J.B.R. Matthews, T.K. Maycock, T. Waterfield, O. Yelekçi, R. Yu, and B. Zhou (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, pp. 1513–1766, doi:10.1017/9781009157896.013.
Seneviratne, S.I. et al., in preparation: Extreme climate events from past to future: A 5-year update since the IPCC AR6 report. Manuscript in preparation.
How to cite: Seneviratne, S. I., Batibeniz, F., Biess, B., Fisch, C., Gudmundsson, L., Haddad, Y. Y., Hirschi, M., Schumacher, D. L., and Zhang, X.: New evidence on observed and attributable changes in water cycle means and extremes: From regional to global scale, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-14873, https://doi.org/10.5194/egusphere-egu26-14873, 2026.
Changes in the terrestrial water cycle reflect not only atmospheric forcing but also how terrestrial ecosystems store and use subsurface water, a component that remains difficult to quantify at large scales. Most observation-based studies rely on surface soil moisture or total water storage anomalies (TWSA) as indicators of ecosystem water availability, although surface soil moisture does not fully represent the water accessed by vegetation, and TWSA integrates multiple storage components that are not necessarily involved in vegetation water use. Here we diagnose active root zone water storage (aSrz), defined as the dynamically operated water volume associated with vegetation water use, using a hybrid ecohydrological framework constrained by precipitation, evapotranspiration, runoff, and terrestrial water storage anomalies. We estimate aSrz and its temporal envelope across the continental United States, and examine its spatial structure and long-term trends. We show that aSrz isolates the vegetation-related component of subsurface water storage and reveals where changes in ecosystem water use are not captured by surface soil moisture or TWSA. Across climate regimes, aSrz remains closely coupled to gross primary productivity anomalies, while surface soil moisture and TWSA often decouple. Regional trends in aSrz further identify where vegetation water access has intensified or weakened relative to ecosystem structure under similar climatic conditions. By explicitly isolating actively exchanged storage, this work provides a new diagnostic for assessing changes in the pace of the terrestrial water cycle.
How to cite: Jiang, S., Blougouras, G., and Reichstein, M.: Active root zone water storage dynamics reveal changes in ecosystem access to subsurface water, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-12263, https://doi.org/10.5194/egusphere-egu26-12263, 2026.
The hydrological cycle has been intensifying globally during the past decades, causing long-term irreversible impacts on the social ecological system. However, research on hydrological regime shifts and their driving mechanisms remains limited. In this study, we selected 13 basins across the Loess Plateau and classified their hydrological regimes from 1990 to 2020 into distinct types using combined indicators of extreme drought and flood flows. Our analysis identified 2005 as the turning point for extreme flows. Hydrological regimes transitioned from a drying trend phase (1990-2005) to a wetting trend phase (2005-2020), characterized by decreasing drought and flood flows before 2005 but increasing trends thereafter across all basins. This shift exhibits a distinct north–south contrast, with larger changes in extreme flows in the northern region than in the southern region. During the drying phase, increased vegetation cover and water use, coupled with reduced mean available water (Mean P-ET, precipitation minus evapotranspiration), were the primary drivers of intensified drying. The wetting phase was triggered by elevated vegetation cover and maximum 14-day available water (Max. P-ET). Notably, vegetation cover emerged as key driver of the drought flows in both periods (p < 0.001), though its regulatory mechanisms shifted between the two phases. Flood flows were influenced by water use and water availability, showing particular sensitivity to variations in Max. P-ET. The shift in hydrological regime suggests that priority should be given to enhancing flood prevention and regulation in future basin management, especially for the northern regions where they are more susceptible to climate change and human activities.
How to cite: Zeng, Y., Wang, C., Gao, G., Chagas, V. B. P., Wang, S., Liu, Y., and Fu, B.: Revegetation and increased precipitation lead to a drying-to-wetting hydrological regime shift in the Loess Plateau of China, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-6530, https://doi.org/10.5194/egusphere-egu26-6530, 2026.
Effective water resource governance requires a fundamental transition from isolated catchment-based approaches to a holistic perspective that integrates atmospheric moisture transport. Large-scale vegetation transitions in upwind regions fundamentally modify evapotranspiration fluxes, triggering "green water" feedbacks that influence hydroclimatological extremes in remote downwind territories. However, integrating these teleconnections into management strategies has been hindered by the limitations of data spatiotemporal resolution. Previous model versions (e.g., WAM-2layers v2) were typically constrained to coarse-resolution (1.5°) ERA-Interim input data, which limited the ability to resolve fine-scale moisture pathways and often conflated localized recycling with regional transport due to spatial averaging. In this study, we propose a framework for "Atmospheric Water Management" utilizing the WAM-2layers v3 model, driven directly by high-resolution (0.25°) ERA5 reanalysis data over the last 30 years. This represents a 6-fold increase in spatial resolution, allowing us to capture the full heterogeneity of anthropogenic landscapes. By utilizing this refined grid, we can distinguish specific moisture transport corridors and recycling loops that were previously obscured by the coarse discretization of earlier studies.
Building on this refined climatology, we apply complex network theory to construct a connection-graph of South America's "flying rivers." This approach enables us to pinpoint critical "moisture hubs"—specific geographic nodes where land-surface integrity exerts the strongest control over water security in downwind agricultural sinks, such as the La Plata Basin. We hypothesize that these hubs act as critical atmospheric infrastructure; their degradation via deforestation weakens the continental network's resilience, amplifying drought intensity downstream. Consequently, we argue that these identified hubs should be prioritized as conservation targets within national land-use planning. By quantifying these source-sink dependencies, this work aims to establish process-based thresholds for delimiting "precipitationsheds," supporting spatial planning where land conservation decisions are recognized as essential upstream water management strategies.
How to cite: Hung, H. T., Weng, W., Tseng, K.-C., Fu, P., and Wang, L.-P.: High-Resolution Moisture Recycling Networks for Atmospheric Water Management in South America, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-11488, https://doi.org/10.5194/egusphere-egu26-11488, 2026.
Human water management—particularly irrigation water withdrawal and use—strongly reshapes land–atmosphere interactions and modulates regional hydroclimate. Yet representation of irrigation processes in land surface and Earth system models remains limited, constraining our ability to assess water management–climate feedbacks at large scales. In this study, we advance the Common Land Model (CoLM) by developing a two-way coupled irrigation scheme that integrates irrigation demand, application, and water withdrawal processes. The new module estimates irrigation water demand based on soil moisture deficit, represents four major irrigation methods, and links irrigation water supply to multiple water sources by coupling CoLM with a river-routing model and a reservoir operation scheme. This framework explicitly resolves dynamic feedbacks between irrigation demand and water availability from runoff, streamflow, reservoirs, and groundwater.
Comprehensive evaluations over the United States show that the enhanced model realistically reproduces irrigation withdrawals, their spatial distribution, and water source proportions, consistent with reported state-level statistics. The new irrigation scheme substantially improves simulations of surface energy fluxes, near-surface temperature, river discharge, and crop yields for major crops. The improved CoLM has now been incorporated into the ISIMIP3 Water (global) sector model intercomparison project, providing a new tool for coordinated global assessments of human water management impacts.
Applications of the new framework further demonstrate its utility in predicting irrigation-induced climate effects and assessing agricultural water use and scarcity. Overall, this work provides an advanced representation of irrigation–climate–water interactions, offering new opportunities to investigate the co-evolution of climate, water resources, and agricultural production, and to support sustainable water management under a changing climate.
How to cite: Zhang, S., Liang, H., and Dai, Y.: Improving irrigation–climate interactions in land surface modeling: Development, validation, and applications of the two-way coupled irrigation framework in CoLM, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-16427, https://doi.org/10.5194/egusphere-egu26-16427, 2026.
Efforts to slow down groundwater depletion requires reliable estimates of the impacts of irrigation on shallow groundwater levels. However, spatial assessment of the effects of irrigation schedule on groundwater level change is still lacking. Here, we present a linked APSIM-MODDLOW model framework to reveal irrigation-groundwater linkages in the plain area of Ziyahe River Basin by considering irrigation schedules, crop yield, ETa and leakage. The linked APSIM-MODLFOW model effectively simulates grain yield and regional groundwater level fluctuations in the winter wheat-summer maize cropping system of the NCP. We found that the simulated grain yield and evapotranspiration increase rapidly with the increase of irrigation frequency, whereas the yield exhibits a gradual increase when irrigation exceeds three times (70 mm each time). The simulated regional average groundwater levels exhibit an increase under rain-fed and single-irrigation scenarios-with irrigation applied at the jointing stage of wheat-whereas a decline is observed under alternative irrigation regimes. These findings indicate that regional groundwater can be replenished through recharge when irrigation schedules range from single-irrigation (applied at the jointing stage of wheat) to double-irrigation (applied at both the jointing stage and the flowering and grain-filling stage of wheat) The unconfined aquifer maintains extraction-recharge equilibrium under the irrigation amount 70 – 140 mm (1-irrigation to 2-irrigations). Spatial distribution of groundwater flow field revealed that to prevent a decline in regional groundwater levels and reduce grain yield loss, the existing 3-irrigations schedule should be maintained in the southern region of study area and Shijin Irrigation District, while a 1-irrigatoin schedule should be implemented in the northern region. These findings can serve as a reference for regional irrigation and groundwater resource evaluation and management. The linked model framework has important implications for other studies where groundwater variations are highly impacted by agriculture irrigation.
How to cite: Liu, X.: Using a linked APSIM-MODFLOW model framework to quantify the impact of irrigation frequency on groundwater level in a typical groundwater over-exploitation region of NCP , EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-6297, https://doi.org/10.5194/egusphere-egu26-6297, 2026.
Media, citizens, and insurance companies in Denmark increasingly report problems and concerns related to rising groundwater levels and groundwater flooding. However, the primary governing causes of these issues remain unclear. The driving factors are believed to include climate-driven changes in precipitation and evapotranspiration, changes in groundwater abstraction, and local anthropogenic alterations of water pathways, such as the renovation of old, leaky sewer systems and the implementation of sustainable drainage systems.
Using groundwater observations from the national well database Jupiter, we investigate the relative impacts of historical climatic changes and changes in groundwater abstraction patterns on observed groundwater levels over the past 33 years in Denmark. This is achieved by selecting long, consistent groundwater time series suitable for trend analysis. Based on these time series, we identify two subsets of monitoring wells: (1) climate-controlled wells and (2) anthropogenically influenced wells, using Transfer Function Noise time-series analysis as implemented in Pastas. The identified groundwater-level trends are compared with trends simulated by the National Hydrological Model of Denmark (DK-model), run with fixed abstraction rates to represent a purely climate-driven signal.
The analysis reveals a pronounced east–west contrast in climatic drivers (precipitation and net precipitation), with increasing trends (wetter) in western Denmark and decreasing trends (drier) in eastern Denmark over the last 33 years. Both the climate-controlled wells and the DK-modelled groundwater levels reproduce this pattern with rising groundwater levels in west (+20 cm over 33yr) and lowering in east (-3 cm over 33yr). Groundwater abstraction patterns in Denmark have changed since the early 1990s, when abstraction levels were significantly higher than today. Wells classified as anthropogenically influenced generally exhibit much larger changes in groundwater-level (often exceeding several meters of increase over the 33 years period) and do not consistently follow the climatic signal, especially for the eastern regions. The analysis shows that while climate impacts can explain moderate increases in groundwater levels in Western Denmark, large increases observed in Eastern Denmark are contributed to changes in abstraction patterns or other anthropogenic factors. This indicates that the most likely drivers behind the growing concerns related to hazards from high groundwater-levels in Denmark are direct anthropogenic changes with climate change playing a secondary role.
How to cite: Seidenfaden, I., Schneider, R., Nilsson, B., and Stisen, S.: Is climate change or abstraction patterns driving historic changes in Danish groundwater levels? , EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-7170, https://doi.org/10.5194/egusphere-egu26-7170, 2026.
Human activity has significant impacts on the river systems. In-stream infrastructure, such as dams and weirs, creates artificial barriers that impede fish passage during periods of low flow; and off-stream structures, such as agricultural farm dams, intercept and extract water. These structures reduce inflow to rivers and extend the frequency and duration of low flow conditions. While the impacts of water interception by farm dams on long-term streamflow have previously been investigated, the consequences for frequency and duration of low flow periods, are poorly understood. In this study, we estimated the influence of farms dams on annual streamflow and on low flow requirements that ensure water flows over in-stream weirs of different heights for the Moorabool River catchment located in southeast Australia. Streamflow in the Moorabool River was simulated using the hydrological model Genie Rural a 4 parametres Journalier (GR4J) + CHEAT1 to assess the potential impact of farm dams on low flows, using data between 1980 to 2020. The spatial and temporal distribution of farm dams and their storage capacity was estimated using remote sensing. Low flow requirements were calculated measuring cease-to-flow conditions in three weirs in the river, and a low flow spell analysis was conducted to assess the impact of farm dams. From 1990-2020, the number of farm dam increased by 163% across the catchment. Including farm dams and water extractions in the hydrological model increased its performance as assessed by the NSE and logNSE. Streamflow reduction was estimated to be between 3% to 65%, contingent on the level of water extractions and number of dams in the catchment. The cumulative impact of farm dams resulted in fewer high flow events and low flows of longer duration. Prevalent low flows would potentially affect the ability of water to go over some weirs. This study presents a comprehensive approach to quantify water resources by including farm dams and measuring cease-to-flow conditions over weirs in the hydrological model. Ongoing hydrological assessments provides a holistic estimate of water resources and determining objective minimum flow requirements to adequately overtop small weirs in a catchment.
Keywords: farm dams, hydrological model, low flows, river barriers.
How to cite: Gutierrez Ramos, P., Robertson, D., Lester, R., and Matthews, T.: Impact of farm dams on streamflow using an objective low-flow threshold from in-stream artificial barriers, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-25, https://doi.org/10.5194/egusphere-egu26-25, 2026.
Conducting attribution analysis of runoff changes serves as a critical scientific basis for unraveling the mechanisms of hydrological process variability and supporting water resources management decision-making. Water discharge into the sea serves as an integrated indicator of basin-scale runoff evolution, and its variation process provides critical reference for assessing river health status. Based on the variability characteristics of water discharge from Yellow River into the sea (WYRS) and considering the frequent flow cessation events during 1972–1998, this study divided the research period into the pre-flow cessation period (1956–1971), flow cessation period (1972–1998), and post-flow cessation period (1999–2022).An improved attribution framework was proposed by combining the high-intensity anthropogenic water withdrawal and consumption processes with the Budyko theory. The results show that the WYRS has declined significantly (p < 0.01) over the past 67 years. Anthropogenic water consumption (AWC) was the dominant factor driving the sharp decline in WYRS during flow cessation period, accounting for 44.45 %. In contrast, changes in underlying surface conditions caused by ecological restoration measures became the primary driver (100.74 %) of further WYRS reduction in the postflow cessation period. Overall, unlike traditional studies based on the Budyko framework, the findings reveal that in addition to the impacts of indirect human activities such as underlying surface changes on runoff in the Yellow River Basin (YRB), direct human activities like AWC also constitute a non-negligible driving factor. This study provides a novel analytical framework for attributing runoff changes in highly human-impacted basins, offering scientific support for water resource management and ecological conservation in the YRB.
How to cite: Zhu, H.: Attribution analysis of runoff evolution in the Yellow River Basin during 1956–2022: A perspective from water discharge into the sea variability, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-1477, https://doi.org/10.5194/egusphere-egu26-1477, 2026.
Posters on site: Fri, 8 May, 16:15–18:00 | Hall A
The complexity, uncertainty, and heterogeneity implicit in multisource data and the dilemma in selecting the objective-specific best dataset make the terrestrial water cycle and water budget analyses challenging across scales. Here, we develop a UI/UX based open-access, flexible, and user-friendly Python software, namely WATcycle (https://github.com/ronikianji/WATcycle). It is useful for varying levels of expertise, reduces the coding overhead, and offers a range of data processing tools. The entire software has six main steps: (1) Data downloading, (2) Data pre-processing, (3) Residual error analysis of water budget components, (4) Validation of datasets with in-situ data, (5) Data plotting, and (6) water budget closure analysis. We test the developed software using a case study on the Amazon basin, which incorporates 79 datasets from various sources, including precipitation, evapotranspiration, surface runoff, TWS, canopy, soil moisture, and groundwater. The spatial plots and trend analysis results correlate with other studies, showing the decreasing trend for precipitation, surface runoff, canopy water storage anomaly, and soil moisture storage anomaly. Meanwhile, evapotranspiration, terrestrial water storage, and groundwater storage anomalies show an increasing trend. Out of these 7 hydrological variables, precipitation and terrestrial water storage anomaly trends are not significant at a 95% significance level. Water budget analysis shows a residual error of -70 to 60 mm/month, which is adjusted using the proportional redistribution water budget closure method. The results show the performance, accuracy, and capabilities of the developed software. It will play a crucial role in skillful inferences for water resource management, risk assessment, and infrastructure planning in the basins globally.
How to cite: Anjaneyulu, R. and Abhishek, A.: WATcycle: Water Analysis Tool for the terrestrial water cycle and water budget, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-171, https://doi.org/10.5194/egusphere-egu26-171, 2026.
Due to its location at the interface between land surface and atmosphere, soil moisture (SM) plays an important role in modulating energy, water and carbon fluxes. During periods of decreasing SM, SM loss is dependent on evapotranspiration (ET), drainage and changes in plant water storage. Investigating SM loss can give important insights into these processes. Here we use 24 years of global remote sensing data to investigate how SM loss is controlled by vegetation and temperature. We find that positive vegetation anomalies lead to slower SM loss in most areas, except for cold boreal forests. We hypothesize that these effects arise through competing effects of soil shading, transpiration and root water uptake by the vegetation. The effect that positive vegetation anomalies increase SM loss is limited to high SM conditions and disappears at lower SM, likely due to water stress limiting transpiration. By analyzing temperature and vegetation anomalies jointly we find that the relationship between SM loss and temperature varies between regions, but vegetation cover effects persist across the full range of temperature anomalies. Using a simple energy and moisture budget model we can reproduce observed vegetation and temperature effects, supporting the interpretation that vegetation controls topsoil SM loss through shading and transpiration. We also find widespread positive SM loss trends which indicates accelerated topsoil water cycling, likely due to higher atmospheric water demand driven by increasing temperatures.
How to cite: Baur, M. J., Vargas Zeppetello, L., Friend, A., and Entekhabi, D.: Control of vegetation and temperature on topsoil water losses, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-1088, https://doi.org/10.5194/egusphere-egu26-1088, 2026.
Soil moisture plays a key role in land-atmosphere interactions by influencing components of the land surface energy balance. It is highly sensitive to variations in groundwater levels, particularly in shallow aquifers where changes in water availability can alter soil moisture dynamics and thus surface fluxes (Vogelbacher et al., 2024). Ongoing declines observed in many of the world's major aquifers (Jasechko et al., 2024) therefore raise questions about potential shifts in soil moisture regimes and their implications for land-atmosphere interactions. In this study, we investigate how aquifer states (i.e., deepening, shallowing, or remaining stable) affect water vapor and heat exchanges between land and atmosphere by focusing on variations of evaporative and sensible heat fluxes. We relate these shifts to extreme heat variations using summer heatwave frequency as a proxy. Our approach integrates groundwater model outputs with in situ measurements over a 16-year period (2000 to 2015) to identify the dominant response variable for each aquifer by calculating correlations between the aquifer trend and environmental variables (e.g., soil moisture, evaporation, soil temperature). Our findings indicate distinct correlation patterns across deepening and stable aquifers, emphasizing the importance of incorporating groundwater dynamics into assessments of soil-moisture temperature feedback and heatwave risk (Vogelbacher et al., 2026). In this context, improved understanding of groundwater land-atmosphere interactions can inform integrative management frameworks that balance hydrological functioning, ecosystem resilience, and human well-being.
References:
Jasechko, S., Seybold, H., Perrone, D., Fan, Y., Shamsudduha, M., Taylor, R. G., Fallatah, O., & Kirchner, J. W. (2024). Rapid groundwater decline and some cases of recovery in aquifers globally. Nature, 625 (7996), 715–721. https://doi.org/10.1038/s41586-023-06879-8
Vogelbacher, A., Aminzadeh, M., Madani,K., Shokri, N. (2024). An analytical framework to investigate groundwater‐ atmosphere interactions influenced by soil properties. Water Resources Research, 60, e2023WR036643. https://doi.org/10.1029/2023WR036643
Vogelbacher, A., Afshar, M. H., Aminzadeh, M., Madani, K., AghaKouchak, A., & Shokri, N. (2026). A global analysis of the influence of shallow and deep groundwater tables on relationships between environmental parameters and heatwaves. Environmental Research, 289, 123354. https://doi.org/10.1016/j.envres.2025.123354
How to cite: Vogelbacher, A., Aminzadeh, M., Madani, K., AghaKouchak, A., and Shokri, N.: How groundwater trends modulate soil moisture feedback and summer heatwave frequency, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-1133, https://doi.org/10.5194/egusphere-egu26-1133, 2026.
Total dissolved gas (TDG) supersaturation induced by high-dam discharge poses a severe threat to fish survival and represents a significant ecological risk in high-dam operations. Conducting fish survival risk assessments under TDG supersaturation is a critical component of environmentally friendly hydropower project construction and safe operation, serving as the scientific foundation for developing effective ecological mitigation measures. Based on historical behavioral experimental data of the endemic Upper Yangtze fish species, Schizothorax prenanti, under TDG supersaturation, combining random forest and hierarchical partitioning. this study identifies exposure time, TDG supersaturation level, and water temperature as the primary drivers influencing fish tolerance in TDG supersaturated water, and TDG supersaturation level and body length emerge as key determinants for avoidance capacity. Prediction formulas for mortality and horizontal avoidance rate were established based on these drivers. A fish tolerance model for TDG supersaturated water was constructed through instantaneous probability transformation, peak mortality definition, and non-negativity constraints. Fish movement behaviors were simplified into three core swimming vectors (random swimming, upstream migration, and horizontal avoidance). After calibrating the weight of each vector, a movement model for fish in TDG supersaturated water was constructed. This model was applied to a spawning ground downstream of a cascade hydropower station in the Yalong River to simulate fish movement trajectories and lethal effects in a dynamically changing TDG-supersaturated environment, including the TDG supersaturation levels experienced by fish, locations of death, and time of death. The results indicated fish possessed the ability to detect tributaries and utilize them to evade high TDG. Therefore, when formulating measures to mitigate the impacts of TDG supersaturation on fish, it is essential to fully consider the spatial patterns of river hydrodynamics and TDG distribution, suggesting to utilize tributaries to creat suitable habitats can enhance fish survival rates. This study marks the first application of fish behavioral patterns derived from laboratory experiments to river simulations. The findings provide technical support for developing fish protection measures downstream of high dams and assessing the ecological risks associated with TDG.
How to cite: Rao, J., Wang, Y., Li, X.-T., Liang, R., and Li, K.: A Fish Movement Model for Assessing the Impacts of Total Dissolved Gas Supersaturation Downstream of High Dams, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-3231, https://doi.org/10.5194/egusphere-egu26-3231, 2026.
The Mediterranean basin is characterised by significant spatial and temporal precipitation variability and is recognised as one of the major climate change hotspots on a global scale, where recent studies have documented an intensification of the hydrological cycle with reduced seasonal precipitation but increased frequency of extreme events. This inherent variability is further compounded by non-climatic factors related to data availability and quality. Historical hydro-climatic databases are often affected by discontinuities and gaps, while recent monitoring networks provide more accurate observations but shorter records, which are frequently insufficient for robust climate trend analyses. In order to address these limitations, gridded datasets have been developed. However, these products may introduce additional uncertainties and potential distortions into the results.
The present study focuses on the Campania region, in Southern Italy, which is characterised by a complex orography and significant discontinuities in the available historical time series. In the 2000s, the regional hydro-climate monitoring network underwent structural restructuring. New sensors were installed, while the existing ones (historical network) were upgraded with new technology. However, only a few stations retained their original location and characteristics, resulting in a discontinuity between the historical database (1918-1999) and the current one. This discontinuity was overcome by reconstructing a single continuous monthly scale precipitation dataset through geostatistical interpolation on a regular grid with a spatial resolution of 10 × 10 km. This reconstruction enables the analysis of an almost centennial (1918-2023) continuous precipitation time series to investigate long-term variability in regional precipitation regimes, which represents furthermore a key driver to investigate changes in hydrological processes. To evaluate climate trends and the reliability of gridded reconstructions, the non-parametric Mann-Kendall and Sen's tests were applied to precipitation at the annual scale in parallel on both datasets (in situ observations and gridded reconstructions).
The results highlight trends indicative of the complexity documented at the Mediterranean scale. For the historical period (1918-1999), in situ observations reveal a predominantly negative trend, consistent with the pattern observed across the Mediterranean basin during the second half of the 20th century, which may indicate a potential reduction in regional water availability. In contrast, the most recent period reveals an inversion of this tendency, with a prevalence of positive trends. Analysis of the gridded reconstructions also confirms these patterns across most of the region, although some local discrepancies are present. Nevertheless, the majority of detected trends, in both datasets and particularly in the most recent period, are not statistically significant.
How to cite: Nicoletti, G., Longobardi, A., and Villani, P.: Gridded versus on site monthly rainfall centennial dataset for climate variability assessment in Campania Region (Southern Italy), EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-14929, https://doi.org/10.5194/egusphere-egu26-14929, 2026.
Posters virtual: Wed, 6 May, 14:00–18:00 | vPoster spot A
EGU26-6269 | ECS | Posters virtual | VPS9
Climate Driven Hydrological Intensification and Its Implications for Water AvailabilityWed, 06 May, 14:33–14:36 (CEST) vPoster spot A
The intensification of hydrological cycle driven by global warming leads to an increase in extreme precipitation events, prolonged droughts and higher rates of evaporation. This global change has altered the global hydrological cycle and effect on the long term water availability in many watersheds worldwide. The impact of climate change is usually assessed by using ratio of stream flows and climate variables, which are formally defined as the climate elasticity of water availability This study examines how the hydrological cycle is intensifying over the Kabul Watershed and how this affects water availability using the water balance (P–E) approch. Here, we used ERA5 land data of annual total precipitation (P) and total surface evaporation (E) from 1976 to 2024 to understand how the land and atmosphere interacted. The climate elasticity of (P-E) to annual water availability is determined for 1976-2010 and validated for 2011-2024. The results reveal 0.8 °C rise in temperature, 12% decline in annual precipitation, and 7% increase in evaporation in the past 25 years. This caused 15% reduction in the P–E balance, which directly reduced the annual water availability. The climate elasticity factor of 0.55 has been determined to water availability in Kabul for the period of 1976-2010. By using this elastic factor, the average water availability of 19.54 MAF is predicted for the period of 2011-2024 whereas the observed water availability is 20.43 MAF. This finding reflects the sensitivity of a watershed to P-E alteration for water availability and underscore the urgent need of climate resilient water management strategies to mitigate the future impacts of climate change in the Kabul watershed.
How to cite: Kosar, T., Rahim, A., Yaseen, M., Naz, R., Mamoor, M., and Akif, A.: Climate Driven Hydrological Intensification and Its Implications for Water Availability, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-6269, https://doi.org/10.5194/egusphere-egu26-6269, 2026.
