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Quantifying changes in global terrestrial evapotranspiration (ET) is essential for understanding how the hydrological cycle responds to climate change. Most current ET estimates are limited to the satellite observation era, starting in the 1980s, leaving the dynamics of global ET over longer time scales, such as the past century, largely unknown. Based on thoroughly validated centennial‐scale global ET rates, estimated by the complementary relationship method, here we show that global ET significantly increased with a trend of 0.08 ± 0.011 mm yr−2 (p < 0.001) during 1901–2014, equivalent to an accumulated relative increase of 1.8 ± 0.2%. This pronounced increase provides robust evidence of the intensification of the hydrological cycle on a centennial scale. The increase in global ET has mainly occurred in the most recent five decades, as the trend during 1966–2014 is five times as large as that during 1901–1965. From 1901 to 2014, the scaling rate of global ET to temperature (ηae) is 1.3 ± 0.3% °C−1. Notably, ηae remains nearly constant across different timescales, despite an accelerated warming and rising atmospheric CO2 concentrations in the recent past. Similar findings of stable ηae values can also be observed in the state‐of‐the‐art land surface models, despite being parameterized in more complex ways. This timescale invariance property may enable the application of a constant ηae value to facilitate predictions of future global ET changes based solely on temperature projections. These findings have relevance for global‐scale water resources management under the ongoing climate change.

Hydrological responses corresponding to the agricultural land use alterations are critical for planning crop management strategies, water resources management, and environmental evaluations. However, accurate estimation and evaluation of these hydrological responses are restricted by the limited availability of detailed crop classification in land use and land cover. An innovative approach using state-of-the-art Variable Infiltration Capacity (VIC) model is utilized by setting up the crop-specific vegetation parameterization and analyse the effect of uniform and heterogeneous agricultural land use over the hydrological responses of the basin, in the Kangsabati River Basin (KRB). Thirteen year simulations (1998–2010) based on two different scenarios i.e., single-crop in agricultural land use (SC-ALU) and multi-crop in agricultural land use (MC-ALU) patterns are incorporated in the model and calibrated (1998–2006) and validated (2007–2010) for the streamflow at Reservoir and Mohanpur in the KRB. The results demonstrated that the VIC model improved the estimates of hydrological components, especially surface runoff and evapotranspiration (ET) at daily and monthly timescales corresponding to MC-ALU than SC-ALU (NSC > 0.7). Grid-scale ET estimates are improved after incorporating heterogeneous agricultural land use (NSC > 0.55 and R2 > 0.55) throughout the period of 1998–2010. This study improves our understanding on how the change in agricultural land use in the model settings alters the basin hydrological characteristics, and to provide model-based approaches for best management practices in irrigation scheduling, crop water requirement, and management strategies in the absence of flux towers, eddy covariance, and lysimeters in the basin.

Understanding how catchments respond to environmental changes is critical for water resource management. However, few studies have systematically linked catchment characteristics, environmental changes, and hydrological responses. Therefore, this study proposes a novel dual‐clustering approach for identifying hydrological response patterns. It constructs the catchment characteristic indicator system for the baseline period and introduces dynamic similarity indicators that reflect climate change and anthropogenic impacts to achieve dual clustering, thereby identifying hydrological response differences. Furthermore, it employs the eXtreme Gradient Boosting (XGBoost) and SHapley Additive exPlanations (SHAP) methods to identify key influencing factors of runoff change significance, providing interpretable insights into differences in hydrological responses. The approach is applied to the Haihe River Basin, indicating that 160 catchments are classified into nine static groups (A1–A9) based on catchment characteristics and five dynamic groups (B1–B5) based on environmental changes. The XGBoost model demonstrates good performance in identifying hydrological response patterns, SHAP analysis identifies the top four important factors as percentage of areas with substantial declines in the water table (positive), proportion of natural land use (positive), degree of humidity (negative), and mean elevation (positive). Catchments located in the northwestern mountainous areas are more susceptible to environmental changes, while those located in the southwestern mountainous areas and the southern plains show relatively stable response patterns. Additionally, environmental change patterns characterized by substantial water table decline are more likely to trigger significant runoff change. This approach provides new insights into the effects of interactions between static catchment characteristics and dynamic environmental changes on hydrological functioning.

River connectivity is essential for maintaining fertile floodplains, healthy ecosystems, and human activities, particularly in semi‐arid regions, where water flow is often intermittent. Despite its importance, very few studies have attempted to quantify connectivity at the scale of individual rainfall‐runoff events. In this study, we present a novel framework for exploring synchronous and sequential connectivity to capture the hydrological response of a system. We distinguish between structural (SC) and functional (FC) connectivity by constructing structural networks utilizing topographic data from the Walnut Gulch Experimental Watershed in Arizona, USA, and correlation‐based functional networks using high‐resolution runoff data. We examine how SC‐FC relations vary across events and how they relate to the hydrological responses of the system. We classify rainfall events via unsupervised clustering and identify the corresponding dominant runoff connectivity patterns within each cluster. The results of our analysis showed that short, intense storms tend to produce localized runoff connectivity, characterized by dominant synchronous SC‐FC relations, whereas larger rainfall events tend to exhibit higher sequential SC‐FC correlation values, indicating widespread system connectivity. Furthermore, our analysis revealed that there is a minimum threshold in the synchronous connectivity value (0.13), before positive sequential activity appears in the system. Comparable synchronous and sequential connectivity values typically indicate that water flow reached the watershed outlet; however, maximum SC‐FC value is not necessarily associated with peak discharge at the watershed outlet. Due to its flexibility, our approach suggests a general framework for analyzing connectivity in any river network with an ephemeral flow regime.

Land use and land cover change (LUCC) can affect the hydrological response time of rivers. However, it is difficult to generate robust and quantitative evidence of this impact at the catchment scale. This lack of evidence also affects the development of rainfall‐runoff models to make ex‐ante predictions. Here, we analyze high‐frequency observational data from a network of pairwise catchments in the tropical Andes and find a statistically significant impact of intensive land use on the hydrological response time, which can be used for regionalization. First, we isolated individual rainfall response events from 5‐min precipitation and discharge time series of 16 catchments (8 pairs). We then fitted unit hydrographs on these events to estimate the catchment response times. These response times were subsequently regionalized by, first, applying a forward stepwise regression to select statistically significant catchment characteristics including land use and land cover, then, fitting a linear mixed‐effects model with the selected characteristics to account for within‐site variability between pairs. We find that catchments with intensive land use have a significantly quicker response than their natural counterparts. Differences were often sub‐hourly, highlighting the value of high‐frequency monitoring. Forward stepwise regression identified only catchment area and intensive land use percentage (LUP) as statistically significant predictors. Model coefficients show that, even when considering other catchment characteristics, increasing intensive LUP decreases response times. This study provides solid evidence and a robust methodology to quantify the impacts of LUCC on catchment hydrology.

In this study, we analyze the impact of reduced snow cover in the Northern Hemisphere on the atmosphere and if the atmospheric response depends on the model resolution. We use the atmospheric component of the global climate model EC-Earth and perform three experiments: in the first experiment, we reduce the snow cover in the entire Northern Hemisphere by reducing the snow albedo to a constant value of 0.3, in the second experiment, we reduce the snow albedo only over Eurasia, and the third experiment is the control run using normal snow conditions. All experiments are integrated over the period 1980–2015 at standard resolution (~ 80 km) and high resolution (~ 40 km). Experiments comprise 11 and 5 ensemble members at standard resolution and high resolution, respectively. Reducing the snow albedo in the Northern Hemisphere leads to 5–10% snow cover reduction in winter and spring. Significant warm responses are found over northern Eurasia in spring and summer with a warm response reaching 3 °C. Similar but weaker warm temperature responses are found in the middle and upper troposphere (up to 2 °C) and reversed temperature responses in the stratosphere (up to – 2 °C), particularly over eastern Eurasia. This is closely associated with westerly jet flow response which is enhanced at high-latitude and weakened at low-latitude in winter and spring over eastern Eurasia. Reduced snow cover leads to warmer surface temperatures that accelerate snow-melting and further lead to different snow-hydrological responses in western and eastern Eurasia and more precipitation occurs over eastern Eurasia (increasing 10–20%), particularly in the Siberian region. When the snow albedo is reduced only in the Eurasian sector, the surface response pattern resembles the results of the Northern Hemisphere experiment. The warm response is slightly weakened about 0.25–0.5 °C over Eurasia and significantly weakened outside of Eurasia. However, the upper air circulation response is much less pronounced over Eurasia. The impact of resolution on the mean surface field response is small yet it is more pronounced on the large-scale circulation response, particularly in spring and winter.

Fushun, located in Northeast China, is prone to debris flow disasters due to its complex topographical and geological conditions. In 2013, large-scale debris flow disasters triggered by a rainstorm broke out, causing hundreds of casualties and serious economic losses. Therefore, it is significant to evaluate the susceptibility and hazard of debris flows in Fushun. Instead of adopting grid units, this research adopts the hydrological response units as the evaluation units and conducts debris flow susceptibility assessment for Fushun area with analytical hierarchical process. By combining the susceptibility with two different precipitation data, hazard assessment is further conducted. Comparison between the two hazard maps is conducted to explore the influence of precipitation on debris flow hazard assessment. Under different precipitation conditions, the debris flow hazard of the same area changes. Statistics on the accuracy of the susceptibility and hazard assessment results is conducted and further compared with the local existing debris flow disaster records, demonstrating that the evaluation results are generally in good consistency with the actual situation in Fushun.

This article investigates the hydrological response and ecological flow in the diversion area from the Hanjiang River to the Weihe River. Quantifies the impact of the inter-basin diversion project on the hydro-ecological environment of the downstream river. MIKE BASIN is initially utilized in this research to create the multi-year reservoir operating model of Sanhekou Reservoir. Then Indicators of Hydrologic Alteration (IHA) and Range of Variability Approach (RVA) are used to evaluate the change degree of hydrological indicators. Secondly, set seven different ecological flow process schemes considering ecological demand and inter-annual wetness and dryness variability. Finally, evaluate the optimization scheme by Analytic Hierarchy Process (AHP). According to the hydrological response results, suggestions are put forward from the perspective of engineering and non-engineering. The results show that the simulation results of the MIKE BASIN have a high degree of fitting with the design results, which verifies the rationality of the model. Under the design scheme, the overall hydrological change of the river is 72.91% and the hydrological response of the river is high changed. Scheme 6 can reduce the overall hydrological change to (56.63%) moderate change under the premise of less impact on economic benefits, and scheme 6 is the optimal scheme. The research results not only guarantee the ecological function of the river but also provide guidance and reference significance for the actual operation of the reservoir.

Climate and land use/land cover (LULC) changes significantly affect Hanjiang River Basin (HRB) hydrology, making it more unpredictable with global warming. Using a patch-generating land-use simulation model, we projected LULC from 2030 to 2100 and applied the VIC model to assess hydrological responses. Then, we quantified the contributions of climate and LULC changes to streamflow at Danjiangkou (DJK) and the basin outlet (OUT), as well as to the water yield in the HRB in four periods: 2021–2040, 2041–2060, 2061–2080, and 2081–2100. The results showed that: (1) the escalating trend of air temperature and precipitation will become more remarkable under the high emissions scenario; (2) the considerable LULC changes include grassland conversion to forests, primarily upstream, and cropland conversion to urban lands, mainly in the middle and downstream areas; (3) under the SSP245 scenario, climate change will decrease streamflow at DJK and OUT by ‒0.67 m 3 /s and ‒1.21 m 3 /s, respectively, with annual water yield varying ‒1.26 ~ 2.00 mm/a. Under the SSP585 scenario, the streamflow in DJK and OUT will rise by 1.67 m 3 /s and 1.62 m 3 /s, with annual water yield ranging from ‒1.06 to 2.89 mm/a; (4) under SSP245, climate change dominates streamflow variability, and in SSP585, it remains the key driver except for 2041–2060. Moreover, LULC changes also play a decisive role in the water yield of a certain area, and their impact on the basin hydrology cannot be ignored. This work provides a guide for watershed management decision-making, especially carbon emission policies and land-use planning, to enable the better allocation of water resources and addressing water supply risks in the future.

Climate change has the potential to reduce water resource availability in the Nile Basin countries in the forthcoming decades. We investigated the sensitivity of water resources to climate change in the Lake Tana Basin, Ethiopia, using outputs from global climate models (GCMs). First, we compiled projected changes in monthly precipitation and temperature in the basin from 15 GCMs. Although the GCMs uniformly suggest increases in temperature, the rainfall projections are not consistent. Second, we investigated how changes in daily temperature and precipitation might translate into changes in streamflow and other hydrological components. For this, we generated daily climate projections by modifying the historical data sets to represent the changes in the GCM climatologies and calculated hydrological changes using the Soil and Water Assessment Tool (SWAT). The SWAT model itself was calibrated and validated using the flows from four tributaries of Lake Tana. For the Special Report on Emissions Scenarios A2 scenario, four of the nine GCMs investigated showed statistically significant declines in annual streamflow for the 2080–2100 period. We interpret our results to mean that anthropogenic climate changes may indeed alter the water balance in the Lake Tana Basin during the next century but that the direction of change cannot be determined with confidence using the current generation of GCMs. Key Points Climate variability Climate change impact on hydrological processes Uncertainty in climate change impact predictions