A screening method for the fast identification of well-specific peculiarities in hydrographs of groundwater head monitoring networks is suggested and tested. The only information required is a set of time series of groundwater head readings all measured at the same instants of time. The results were used to check the data for measurement errors and to identify wells with possible anthropogenic influence.

We investigate the impact of revegetation on the hydrology of the Loess Plateau based on high-resolution simulations using the Weather Research and Forecasting (WRF) model. We find that past revegetation has caused decreased runoff and soil moisture with increased evapotranspiration as well as little response from rainfall. WRF suggests that further revegetation could aggravate this water imbalance. We caution that further revegetation might be unsustainable in this region.

How far can we reach in predicting river flow globally, using integrated catchment modelling and open global data? For the first time, a catchment model was applied world-wide, covering the entire globe with a relatively high resolution. The results show that stepwise calibration provided better performance than traditional modelling of the globe. The study highlights that open data and models are crucial to advance hydrological sciences by sharing knowledge and enabling transparent evaluation.

In many places, seasonal variability in precipitation and evapotranspiration (climate) leads to seasonal variability in river flow (streamflow). In this work, we explore how climate seasonality is transformed into streamflow seasonality and what controls this transformation (e.g. climate aridity and geology). The results might be used in grouping catchments, predicting the seasonal streamflow regime in ungauged catchments, and building hydrological simulation models.

Accurately estimating coupling of evapotranspiration (ET) and soil water content (θ) at different depths is key to investigating land–atmosphere interaction. Here we examine whether the model can accurately represent surface θ (θ_s) versus ET coupling and vertically integrated θ (θ_v) versus ET coupling. We find that all models agree with observations that θ_s contains slightly more information with fPET than θ_v. In addition, an ET scheme is crucial for accurately estimating coupling of θ and ET.

A method for linking releases of a storm overflow with the precipitation-forming mechanism, depending on air circulation, was presented. The logit model was used to simulate overflow releases, and a rainfall generator accounting for a forming mechanism was used for forecasting. It was found that the logit model is universal and can be applied to a catchment with diverse geographical characteristics and that the precipitation-forming mechanism has an impact on the operation of the storm overflow.

The new generation of satellite soil moisture observations are used to correct the streamflow in a regional-scale river basin simulated by a mathematical model. The correction is done via both the direct updating of soil moisture and correction of rainfall input. Results show some streamflow improvement, but the magnitude is small. A larger improvement will need future generations of even higher-quality satellite soil moisture data and better process representation in the mathematical model.

The AquiFR hydrogeological modelling platform aims to provide short-term-to-seasonal hydrological forecasts over France for daily water management and long-term simulations for climate impact studies. The results described in this study confirm the feasibility of gathering independent groundwater models into the same numerical tool. This new tool encourages the development of groundwater modelling, and it has the potential to be valuable for many operational and research applications.

The groundwater regime in cold regions is strongly impacted by the soil freeze–thaw processes and semiarid climatic conditions. In this paper, we incorporate groundwater dynamics in the Noah-MP land surface model to simulate the water exchange between the unsaturated soil zone and an unconfined aquifer in the Prairie Pothole Region. The water table dynamics are reasonably simulated. The water budget of groundwater aquifer under current and future climate are also investigated.

We present the first annually resolved stable isotope record (1819–1998) from shells of Swedish river mussels. Data reflect hydrological processes in the catchment and changes in the isotope value of local precipitation. The latter is related to the origin of moisture from which precipitation formed (North Atlantic or the Arctic) and governed by large-scale atmospheric circulation patterns. Results help to better understand climate dynamics and constrain ecological changes in river ecosystems.

We compare lake models with different complexity focusing on the key factors (e.g., eddy diffusivity) which can have an influence on the distribution of the dissolved gases in water. For the first time, we compare the biogeochemical modules in the ALBM and LAKE models. The result showed a good agreement with observed data (O₂), but not for CO₂. It indicates the need to improve the representation of physical and biogeochemical processes in lake models.

Secondary dryland salinity is a global land degradation issue. Our understanding of causal processes is adapted from wet and hydrologically connected landscapes and concludes that low end-of-catchment runoff indicates land clearing alters water balance in favour of increased infiltration and rising groundwater that bring salts to the surface causing salinity. This study shows surface flows play an important role in causing valley floor recharge and dryland salinity in low-gradient landscapes.

This study quantifies uncertainties in the prediction of long-term water balance for mine reclamation soil covers using random sampling of model parameter distributions. Parameter distributions were obtained from model optimization for field monitoring data. Variability in climate is a greater source of uncertainty than the model parameters in evaporation predictions, while climate variability and model parameters exert similar uncertainty on predictions of net percolation.

We revisit and shed light on the textbook The Extraction of Hidden Waters by the Persian mathematician and engineer Abubakr Mohammad Karaji. Ground-breaking ideas and descriptions of hydrological and hydrogeological perceptions such as components of the hydrological cycle, groundwater quality and driving factors for groundwater flow were presented in the book. We speculate that Karaji's book is the first of its kind to provide a construction and maintenance manual for an engineering project.

We assessed the impact of initial conditions on convection-permitting simulations of a flood event over mountainous terrain. The calibrated convection-permitting model performs better than the simpler conceptual model. Discharge is slightly more sensitive to spin-up time than precipitation due to the influence of soil moisture. A maximum of 0.5 m of snow is converted to runoff irrespective of the initial snow depth, and this snowmelt contributes to discharge mostly during peak flow period.

We focus on the net exchange of water between land and air via evapotranspiration and dew during the night. We provide, for the first time, an overview of the magnitude and variability of this flux across the globe from observations and climate models. Nocturnal water loss from land is 7 % of total evapotranspiration on average and can be greater than 15 % locally. Our results highlight the relevance of this often overlooked flux, with implications for water resources and climate studies.

We proposed an approach that integrates universal multifractals and a segmentation algorithm to precisely identify extreme precipitation (EP) and assess spatiotemporal EP variation over the Loess Plateau, using daily data. Our results explain how EP contributes to the widely distributed severe natural hazards. These findings are of great significance for ecological management in the Loess Plateau. Our approach is also helpful for spatiotemporal EP assessment at the regional scale.

This study developed predictive models to represent the spatial and temporal variation of stream water quality across Victoria, Australia. The model structures were informed by a data-driven approach, which identified the key controls of water quality variations from long-term records. These models are helpful to identify likely future changes in water quality and, in turn, provide critical information for developing management strategies to improve stream water quality.

During dry weather, different delayed sources of runoff (e.g. from groundwater, wetlands or snowmelt) modulate the magnitude and variability of streamflow. Hydrograph separation methods often do not distinguish these delayed contributions and mostly pool them into only two components (i.e. quickflow and baseflow). We propose a method that uncovers multiple components and demonstrates how they better reflect streamflow generation processes of different flow regimes.

Urban drainage models are usually calibrated using a few events so that they accurately represent a real-world site. This paper compares 14 single- and two-stage strategies for selecting these events and found significant variation between them in terms of model performance and the obtained values of model parameters. Calibrating parameters for green and impermeable areas in two separate stages improved model performance in the validation period while making calibration easier and faster.

Recharge assessment in the shared transboundary Western Aquifer Basin is highly relevant, scientifically as well as hydropolitically (in Israeli–Palestinian water negotiations). Our unique combination of field-measured soil characteristics and soil moisture time series with soil moisture saturation excess modelling provides a new basis for the spatial differentiation of formation-specific groundwater recharge (at any scale), applicable also in other previously ungauged basins around the world.

This paper provides the documentation of the REGEN dataset, a global land-based daily observational precipitation dataset from 1950 to 2016 at a gridded resolution of 1° × 1°. REGEN is currently the longest-running global dataset of daily precipitation and is expected to facilitate studies looking at changes and variability in several aspects of daily precipitation distributions, extremes and measures of hydrological intensity.

Lateral carbon fluxes from terrestrial to aquatic systems remain central uncertainties in determining ecosystem carbon balance. This work explores how temperature and hydrology control production and export of dissolved organic carbon (DOC) at the catchment scale. Results illustrate the asynchrony of DOC production, controlled by temperature, and export, governed by flow paths; concentration–discharge relationships are determined by the relative contribution of shallow versus groundwater flow.

Studies of the surface energy balance of the earth (SEB) often show that measured incoming energy exceeds the sum of measured outgoing energy terms. The present study models two contributions to the outgoing terms of the SEB: (a) water vapor and dry air as non-ideal gases and (b) the contribution of evaporation to the convective heat. As anticipated, the results are insufficient to resolve the closure mystery, but they should provide insights into atmospheric thermodynamics and the SEB.

Fluorescent tracers such as uranine and sulforhodamine B are useful tools to gain knowledge about water and solute fluxes in aquatic and terrestrial ecosystems. In this study we systematically investigated the influence of important soil properties (pH, organic carbon content and texture) on tracer adsorption in soils and sediments. These properties also determine whether the tracers in the respective soil behave conservatively or non-conservatively.

Between 1992 and 2012, concentrations of suspended sediment decreased at about 60 % of 137 US stream sites, with increases at only 17 % of sites. Sediment trends were primarily attributed to changes in land management, but streamflow changes also contributed to these trends at > 50 % of sites. At many sites, decreases in sediment occurred despite small-to-moderate increases in the amount of anthropogenic land use, suggesting sediment reduction activities across the US may be seeing some success.

Reference evapotranspiration (ET₀) forecasts play an important role in agricultural, environmental, and water management. This study evaluated probabilistic post-processing approaches for improving daily and weekly ensemble ET₀ forecasting based on single or multiple numerical weather predictions. The three approaches used consistently improved the skill and reliability of the ET₀ forecasts compared with the conventional method, due to the adjustment in the spread of the ensemble forecast.