Our study introduces a new method to improve flood forecasting by combining soil moisture and streamflow data using an advanced data assimilation technique. By integrating field and reanalysis soil moisture data and assimilating this with streamflow measurements, we aim to enhance the accuracy of flood predictions. This approach reduces the accumulation of past errors in the initial conditions at the start of the forecast, helping to better prepare for and respond to floods.

To understand how ecohydrological variables evolve jointly and why, this study develops a framework using correlation and causality to construct complex relationships between variables at the system level. Causality provides more detailed information that the compound causes of evolutions regarding any variable can be traced. Joint evolution is controlled by the combination of external drivers and direct causality. Overall, the study facilitates the comprehension of ecohydrological processes.

In this study, we use climate model simulations and process-based ecohydrological modeling to assess the effects of solar radiation changes on hydrological variables. Results show that direct changes in solar radiation without the land–atmosphere feedback primarily affects sensible heat with limited effects on hydrology and vegetation. However, including land–atmosphere feedbacks exacerbates the effects of radiation changes on evapotranspiration and modifies vegetation productivity.

We investigate the potential of long-term satellite and reanalysis products for characterising soil drying by analysing their 2000–2022 soil moisture trends and their representation of agroecological drought events of this period. Soil moisture trends are globally diverse and partly contradictory between products. This also affects the products' drought-detection capacity. Based on the best-estimate products, consistent soil drying is observed over more than 40 % of the land area covered.

We assess changes in blue and green water scarcity in an anthropogenic highly impacted watershed and their association with climate change and land use change, using the multi-water-flux validated Soil and Water Assessment Tool. Observed streamflow, evapotranspiration, and soil moisture are integrated into model calibration and validation. Results show that both climate change and land use change decrease blue water, while land use change increases green water.

Flood peak distributions indicate how likely the occurrence of an extreme flood is at a certain river. If the distribution has a so-called heavy tail, extreme floods are more likely than might be anticipated. We find heavier tails in small catchments compared to large catchments, and spatially variable rainfall leads to a lower occurrence probability of extreme floods. Spatially variable runoff does not show effects. The results can improve estimations of probabilities of extreme floods.

The Unsolved Problems in Hydrology (UPH) initiative has emphasized the need to establish networks of multi-decadal hydrological observatories to tackle catchment-scale challenges on a global scale. This opinion paper provocatively discusses two endmembers of possible future hydrological observatory (HO) networks for a given hypothesized community budget: a comprehensive set of moderately instrumented observatories or, alternatively, a small number of highly instrumented supersites.

Reliable quantification of the amount and variability of evapotranspiration (ET) on the Tibetan Plateau is important for understanding the regional water cycle and resources. This study compares 22 ET products and finds that the mean annual ET over the Tibetan Plateau is 333.1 mm yr^-1, and most products show an increasing trend. It also finds that soil evaporation is the largest contributor to total ET and that contributions from open-water evaporation and snow/ice sublimation cannot be ignored.

The Yellow River basin shows worsening water stress indicators (WSIs) over 1965‒2020. Water withdrawal is the main factor driving WSI before 2000, balanced by water availability. Local water yield and upstream flows are key drivers of sub-basin water availability. Water demand is expected to rise by 6.5 % in the 2030s, creating an 8.36 km³ surface water deficit. Enhanced irrigation efficiency can cut this deficit by 25 %, maintaining the stress level but worsening it for 44.9% of the population.

We developed a device (named VapAuSa) that automates stable water isotope analysis. Stable water isotopes are a natural tracer that many researchers use to investigate water (re-)distribution processes in environmental systems. VapAuSa helps to analyse such environmental samples by automating a formerly tedious manual process, allowing for higher sample throughput. This enables larger sampling campaigns, as more samples can be processed before reaching their limited storage time.

Floodplain trees play a crucial role in increasing flow resistance. Their impact extends beyond floodplains to affect the main channel. The experiments reveal the influence of floodplain trees on the discharge capacity of channels with varying roughness. We determine resistance coefficients for different roughness levels of the main channel bottom. The research contributes to a deeper understanding of open-channel flow dynamics and has practical implications for river engineering.

Soil moisture memory (SMM) shows how long soil stays moist after rain, impacting climate and ecosystems. Current models often overestimate SMM, causing inaccuracies in evaporation predictions. We enhanced a land model, Noah-MP, to include better water flow and ponding processes, and we tested it against satellite and field data. This improved model reduced overestimations and enhanced short-term predictions, helping create more accurate climate and weather forecasts.

We calibrate a global hydrological model using multiple observations to analyse the benefits and trade-offs of multi-variable calibration. We found such an approach to be very important for understanding the real-world system. However, some observations are very essential to the system, in particular, streamflow. We also showed uncertainties in the calibration results, which are often useful for making informed decisions. We emphasize considering observation uncertainty in model calibration.