Recent  

Common intuition holds that higher input data resolution leads to better results. To assess the benefits of high-resolution data, we conducted simulation experiments using data with various temporal resolutions across multiple catchments, and found that higher resolution data does not always improve model performance, challenging the necessity of pursuing such data. In catchments with small areas or significant flow variability, high-resolution data is more valuable.

A systematic laboratory experiment elucidates two-phase heat transport due to water flow in saturated porous media to understand thermal propagation in aquifers. Results reveal delayed thermal arrival in the solid phase, depending on grain size and flow velocity. Analytical modeling using standard local thermal equilibrium (LTE) and advanced local thermal non-equilibrium (LTNE) theory fails to describe temperature breakthrough curves, highlighting the need for more advanced numerical approaches.

Groundwater recharge and flow processes are difficult to quantify on a larger scale. Therefore, it is difficult to assess groundwater resources, substantially used for fresh water supply, and their changes over time. In karst areas, groundwater drainage networks over large areas are generated due to the soluble rocks. The observation of discharge from springs provides an alternative to estimate changes in groundwater resources over time, which can be connected to changing climatic conditions.

The glacier-expanded SWAT version, SWAT-GL, was tested in four different catchments. The assessment highlighted the capabilities of the glacier routine. It was evaluated based on the representation of glacier mass balance, snow cover and glacier hypsometry. It was shown that glacier changes over a long time scale could be adequately represented, leading to promising potential future applications in glaciated and high mountain environments.

Our study conducted a detailed analysis of runoff component and future trend in the Yarlung Tsangpo River basin owing to the existed differences in the published results, and find that the contributions of snowmelt and glacier melt runoff to streamflow were limited, both for ~5 % which were much lower than previous results. The streamflow there will continuously increase in the future, but the overestimated contribution from glacier melt would lead to an underestimation on such increasing trend.

A new drought characteristic, i.e., the duration of drought onset is proposed to depict how rapid drought develops. The roles of pre-drought and post-drought high temperatures on drought onset are quantified. High temperatures behave differently among areas with different vegetation conditions.

This study assesses the value of Seasonal Flow Forecasts (SFFs) in informing decision-making for drought management in South Korea and introduces a novel method for assessing value benchmarked against historical operations. Our results show the importance of considering flow forecast uncertainty in reservoir operations. But the difference in value between SFFs and Ensemble Streamflow Prediction is negligible. The method for selecting a compromise release schedule is a key control of the value.

In this study, we present a detailed characterisation of flash drought in United Kingdom over the period 1969–2021.The spatiotemporal distribution of flash droughts is highly variable, with important regional and seasonal contrasts. In the UK, flash drought occurrence responds primarily to precipitation variability, although the atmospheric evaporative demand (AED) is important as a secondary driver. The atmospheric and oceanic conditions during flash droughts development were also analyzed.

This study explores how to improve models predicting water flow in South Vietnam's Saigon and Dongnai rivers, where data is scarce. By testing three different methods to adjust the river model using river water level and river discharge measurements, we found ways to better predict river behavior. These findings can help manage water resources more effectively and aid decision-making for flood protection and environmental conservation.

Estimating the sizes of flood events is critical for flood-risk management and other activities. We used data from several sources in a statistical analysis of flood size for rivers in the Philippines. Flood size is mainly controlled by the size of the river catchment, along with the volume of rainfall. Other factors, such as land-use, appear to play only minor roles in flood size. The results can be used to estimate flood size for any river in the country alongside other local information.

We accomplished an interdisciplinary study to study the Fuente de Piedra (FdP) playa-lake evolution in southern Spain. We made water balances during the FdP lifespan . Our results indicate that the FdP playa-lake level moved and tilted towards SW caused by active faults.

Flash drought (FD) in the North China Plain (NCP) from 1981 to 2022 was identified by three methods. It occurs more frequently in central and northern NCP than southern, with longer duration in southern and eastern NCP. FD shows seasonal variations. NCP is prone to severe FDs. There is a decreasing trend in FD, with three hotspots in northwestern, eastern and southwestern NCP. The FD frequency is affected by thresholds in the identification methods. This study may be valuable for FD mitigation.

This study explores the timing and content of media coverage (i.e., newspaper articles) of droughts in England. We found that media coverage generally coincides with meteorological drought, but the inverse case did not always generate media coverage. Dominant topics include the water deficiency and weather forecasts, but also the mismanagement of water companies and hosepipe bans, highlighting current challenges in water management practices in England.

Soil moisture is crucial for the water cycle since it is the frontline of drought. Satellite, model, and in-situ data help identify soil moisture stress but challenged by data uncertainties. This study evaluates trends and data coherence of common active/passive microwave sensors and model-based soil moisture data against in-situ stations across Europe from 2007 to 2022. Data reliability is increasing but combining data types improves soil moisture monitoring capabilities.

Our research compares two techniques, Bias-Correction (BC) and Data Assimilation (DA), for improving river flow forecasts across 316 UK catchments. BC, which corrects errors post-simulation, showed broad improvements, while DA, adjusting model states pre-forecast, excelled in specific conditions like snowmelt and high base flows. Each method's unique strengths suit different scenarios. These insights can enhance forecasting systems, offering reliable and user-friendly hydrological predictions.

Root water uptake strongly affects plant development and soil water balance. We use novel upscaling methods to develop land surface and crop models from detailed mechanistic models. We examine the mathematics behind this upscaling, pinpointing where errors occur. By simulating different crops and soils, we found that the accuracy loss varies based on root architecture and soil type. Our findings offer insights into balancing model complexity and accuracy for better predictions in agriculture.

We provide a method how to estimate extreme rainfall from radar observations. Extreme value statistic is applied for observed radar rainfall covering different areas from point size up to about 1000 km². The rainfall extremes are supposed to be as higher as smaller the area is. This behaviour could not be confirmed by the radar observations. The reason is the limited single point sampling approach of the radar data. New multiple point sampling strategies are proposed to mitigate this problem.

Stream temperature sensitivity in northern regions responds to many of the same environmental controls as in temperate regions, but the presence of annually frozen ground (permafrost) influences catchment hydrology and stream temperature regimes. Permafrost can have positive and negative influences on thermal regimes. The net effect of northern environmental change on stream temperature is complex and uncertain, but permafrost will likely play a role through its control on cold region hydrology.

In general, water infiltration systems in peat meadows reduce groundwater level lowering and yearly vertical soil dynamics. Groundwater level fluctuations induce soil volume decreases and increases in both the saturated and unsaturated zone, causing yearly soil dynamics of up to 10 cm. Multi-year subsidence rates are in the order of mm/yr. Such research is vital to increase knowledge on subsidence processes and to develop effective measures to reduce land subsidence and greenhouse gas emission.

In areas heavily influenced by monsoon climates, external factors, like the seasonal winds, typhoons typical of monsoon regions, can disrupt the connection between soil moisture and air humidity. The pattern of actual evapotranspiration becomes more unpredictable and irregular, the conventional Complementary Relationship shows unexpectedly high uncertainty , which was validated through the data from special instruments like flux towers, evaporimeters, and weather stations.

This study examined how water availability, climate dryness, and plant productivity interact at the catchment scale. Using various indices and statistical methods, it found a 0–2-month lag in these interactions. Strong correlations during peak productivity months were observed, with a notable hysteresis effect in vegetation response to changes in water availability and climate dryness. The findings help better understand catchment responses to climate variability.

This study evaluates the effectiveness of Wallonia's sustainable nitrogen management program against groundwater nitrate contamination, 20 years post-implementation. We analysed nitrate concentration time series from 36 locations, finding a modest overall improvement and variability across sites. Results reveal interrelated controlling factors, with land use and aquifer characteristics being key. Lack of improvement may be due to a time lag before the impact of regulatory measures is observable.

When water infiltrates into a snowpack, it alters the thermal state of the system. This work presents a first of its kind multi-phase heat transfer model for local thermal non-equilibrium scenarios of water infiltration into an existing snowpack, such as during Rain-on-Snow events. The model can be used to calculate the formation of ice layers as well as partial melting of the snow. Hence, it can support hazard assessment for flash floods and snow avalanches.

Uncrewed Aerial Systems (UAS) lidar and structure-from-motion (SfM) photogrammetry are effective methods for mapping high-resolution snow depths. However, there are limited studies comparing their performance across different surface features and tracking spatial patterns of snowpack changes over time. Our study found that UAS lidar outperformed SfM photogrammetry. With limited wind effects, the snow spatial structure captured by UAS lidar remained temporally stable throughout the snow season.

Future extreme rainfall events are influenced by changes in both absolute and relative humidity. The impact of increasing absolute humidity is reasonably well understood, but the role of relative humidity decreases over land remains largely unknown. Using hourly observations from France and The Netherlands, we find that lower relative humidity generally leads to more intense rainfall extremes. This relation is only captured well in recently developed convection-permitting climate models.

We introduce a machine-learning framework to study flood spatial characteristics and drivers in eastern China, using 37 years of flood peak data from a vast gauging network. Our analyses provide better understanding of contrasting flood behaviors by explicitly characterizing their spatial extents. This knowledge can help improve flood risk management.

In this article, we show that by taking the optimal parameters calibrated with a semi-lumped model for the discharge at a catchment's outlet, we can accurately simulate runoff at various points within the study area, including three nested and three neighboring catchments. In addition, we demonstrate that employing more intricate melt models, which better represent physical processes, enhances the transfer of parameters in the simulation, until an overparametrization limit is reached.

Our study develops a new model to study groundwater flow under uncertainty, using mathematical techniques to improve accuracy and efficiency. This approach allows for better management of water resources, particularly in drought-prone areas, by providing more reliable groundwater availability and movement estimations. This research combines traditional techniques with innovative methods to address water scarcity and support sustainable water use.

This study assesses how on-farm reservoirs (OFRs) can impact surface hydrology in Eastern Arkansas, US, using a new framework combining remote sensing and hydrological modeling. Findings show that reservoirs can reduce annual flow by 14–24 % and peak flow by 43–60 %, with effects varying by location and reservoirs's capacity. This is relevant as the number of OFRs is expected to increase globally as an adaptation to climate change under severe drought conditions.

In mountainous areas, the relationship between slope and annual hydrological processes is pronounced. However, at lower elevations, this relationship is weak in steeper watersheds. In addition, urbanization leads to an increase in annual surface runoff in all watersheds, especially in steep-slope watersheds. Flatter watersheds exhibit a buffering capacity against urbanization. However, this buffering capacity is diminishing as annual rainfall intensity increases.