Glacial lake outburst floods pose a significant threat to downstream communities and infrastructure as they rapidly unleash stored lake water. Nepal is home to many potentially dangerous glacial lakes, yet a holistic understanding of the hazards faced by these lakes is lacking. This study develops a framework using remotely sensed data to investigate the hazards and risks associated with each glacial lake and discusses how this assessment may help inform future management actions.

Quantifying water and heat fluxes in the shallow subsurface is particularly important due to their strong control on recharge, evaporation and biogeochemical processes. This study developed and tested a new inversion scheme to estimate subsurface hydro-thermal parameters by joint using different hydrological, thermal and geophysical data. It is especially useful for the increasing number of studies that are taking advantage of autonomously collected measurements to explore ecosystem dynamics.

The authors apply an object-based geomorphometric procedure to define the runoff contribution areas. The results enabled us to identify the contribution area related to the different runoff components activated during the storm events through an advanced hydro-chemical analysis. This kind of approach could be useful applied to similar, rainfall-dominated, forested and no-karst Mediterranean catchments.

The climate is subject to variations which must be considered studying the intensity and frequency of extreme events. We introduce in this paper a new methodology for the study of variable extremes, which consists in detecting the pattern of variability of a time series, and applying these patterns to the analysis of the extreme events. This technique comes with advantages with respect to the previous ones in terms of accuracy, simplicity, and robustness.

Many flood disaster impacts could be avoided by preventative action; however, early action is not guaranteed. This article demonstrates the design of a new system of forecast-based financing, which automatically triggers action when a flood forecast arrives, before a potential disaster. We establish "action triggers" for northern Uganda based on a global flood forecasting system, verifying these forecasts and assessing the uncertainties inherent in setting a trigger in a data-scarce location.

This paper uses the natural geochemical tracer Rn together with streamflow measurements to differentiate between actual groundwater inflows and water that exits the river, flows through the near-river sediments, and subsequently re-enters the river downstream (parafluvial flow). Distinguishing between these two components is important to understanding the water balance in gaining streams and in managing and protecting surface water resources.

This study investigates the way bias correcting precipitation forecasts can improve the skill of streamflow forecasts at extended lead times. Eight variants of bias correction approaches based on the linear scaling and the distribution mapping methods are applied to the precipitation forecasts prior to generating the streamflow forecasts. One of the main results of the study is that distribution mapping of daily values is successful in improving forecast reliability.

The paper includes a review of the current state of high-frequency monitoring in groundwater and surface waters as an outcome of a special issue of HESS and four sessions at EGU on this topic. The focus of the paper is to look at how high-frequency monitoring can be used as a valuable support to assess the management efforts under various EU directives. We conclude that we in future will see a transition from research to implementation in operational monitoring use of high-frequency sensors.

In the Anthropocene, drought cannot be viewed as a natural hazard independent of people. Drought can be alleviated or made worse by human activities and drought impacts are dependent on a myriad of factors. In this paper, we identify research gaps and suggest a framework that will allow us to adequately analyse and manage drought in the Anthropocene. We need to focus on attribution of drought to different drivers, linking drought to its impacts, and feedbacks between drought and society.

Possible transient futures of winter and summer low flows for two snow-influenced catchments in the southern French Alps show a strong decrease signal. It is however largely masked by the year-to-year variability, which should be the main target for defining adaptation strategies. Responses of different hydrological models strongly diverge in the future, suggesting to carefully check the robustness of evapotranspiration and snowpack components under a changing climate.

This study reveals the effects of groundwater-dependent evapotranspiration (GDE) in the shift of annual water balance for a catchment in the Budyko space. The ABCD model is modified to incorporate GDE in simulating the monthly hydrological behaviors of a catchment, and the results are aggregated to annual data. GDE enhances the occurrence of excess evapotranspiration (E / P > 1) in dry years, which could not be captured by the traditional Budyko curves. Six catchments are analyzed with the model.

Our paper explores the reliability of conceptual catchment models in the dry Andes. First, we show that explicitly accounting for irrigation water use improves streamflow predictions during dry years. Second, we show that sublimation losses can be easily incorporated into temperature-based melt models without increasing model complexity too much. Our work also highlights areas requiring additional research, including the need for a better conceptualization of runoff generation processes.

We present a review of how transport and fate of micropollutants, i.e., pharmaceuticals and pesticides that are found in groundwater worldwide, can be studied using a laboratory setup of column experiments. Hereby, transport relevant processes are presented and which compounds and which of their properties can be studied with column experiments. We discuss advantages of this laboratory method and show weaknesses and problems.

In the field of cancer research, a scandal occurred at Duke University in the USA in which independent researchers were unable to repeat analysis performed by another group. This led to recommendations by the university and governing organizations to motivate the use of scripting languages to enhance repeatability of research. The hydrology community can easily adopt similar protocols to enhance the integrity of our data analysis and modeling.

While the assessment of "vertical" (magnitude) errors of streamflow simulations is standard practice, "horizontal" (timing) errors are rarely considered. To assess their role, we propose a method to quantify both errors simultaneously which closely resembles visual hydrograph comparison. Our results reveal differences in time–magnitude error statistics for different flow conditions. The proposed method thus offers novel perspectives for model diagnostics and evaluation.

A technology for the spatial derivation of soil texture classes is presented. Information about soil texture is key for predicting the local and regional hydrological cycle. It is needed for the calculation of soil water movement, the share of surface runoff, the evapotranspiration rate and others. Nevertheless, the derivation of soil texture classes is expensive and time-consuming. The presented technique uses soil samples and remotely sensed data for estimating their spatial distribution.

Based on ECMWF's two reanalysis datasets, our assessment of the spatiotemporal trends revealed an average warming of 1.26 °C [0.8 to 1.8] in Turkey from 1979 to 2010. With respect to the regional trends in hydrological variables, ERA-Interim and ERA-Interim/Land revealed quite different pictures. Based on ERA-Interim/Land, which was closer to the observations, there have been no widespread and strong hydrological trends for the same period throughout the country despite the strong warming.

The western African Sahel region has been one of the most important research areas for studying climatic variability due to its fragile climate conditions. Between 1950 and 2012, summer rainfall in the Sahel changed from a multi-decadal decreasing trend to an increasing trend (positive trend shift) in the mid-1980s. We found that this trend shift was synchronous with similar trend shifts in global oceanic evaporation and in land precipitation on all continents except the Americas.

This review paper investigates the determinants of modelling choices for numerous applications of 1-D free-surface flow and morphodynamics in hydrology and hydraulics. Each case study has a signature composed of given contexts (spatiotemporal scales, flow typology, and phenomenology) and chosen concepts (refinement and subscales of the flow model). This review proposes a normative procedure possibly enriched by the community for a larger, comprehensive and updated image of modelling strategies.

The influence of riparian evapotranspiration (ET) on stream hydrology and chemistry is poorly understood. We investigated temporal changes in riparian ET, stream discharge and nutrient chemistry along a Mediterranean catchment. Despite being a small component of annual water budgets (4.5 %), our results highlight that riparian ET drives stream and groundwater hydrology in Mediterranean catchments and, further, question the potential of the riparian zone as a natural filter of nitrogen loads.

Here we present a strategy to use globally available datasets in the calibration function used to convert observed moderated neutron counts into volumetric soil water content. While local sampling protocols are well documented for fixed probes, the use of roving probes presents new calibration challenges. With over 200 fixed probes and 10 roving probes in use globally, we anticipate this paper will serve as a keystone for the growing cosmic-ray neutron probe and hydrologic community.

The 2-year measurements of δ²H and δ¹⁸O in rainfall, stream, soil, and groundwater revealed that surface and groundwater are isotopically disconnected from the annual precipitation cycle but showed bidirectional interactions in the Schwingbach catchment. We established a hydrological model to estimate spatially distributed groundwater ages and flow directions. Our model revealed complex age dynamics and showed that runoff must have been stored in the catchment for much longer than event water.

In Alpine catchments, snowmelt is a major contribution to runoff. In this study, we address the question of whether the performance of a hydrological model can be enhanced by integrating data from an external snow monitoring system. To this end, a hydrological model was driven with snowmelt input from snow models of different complexities. Best performance was obtained with a snow model, which utilized data assimilation, in particular for catchments at higher elevations and for snow-rich years.

The value of using moving cars for rainfall measurement purposes (RCs) was investigated with laboratory experiments by Rabiei et al. (2013). They analyzed the Hydreon and Xanonex optical sensors against different rainfall intensities. A continuous investigation of using RCs with the derived uncertainties from laboratory experiments for areal rainfall estimation as well as implementing the data in a hydrological model are addressed in this study.

The hydrologic reference stations website (www.bom.gov.au/water/hrs/), developed by the Australia Bureau of Meteorology, is a one-stop portal to access long-term and high-quality streamflow information for 222 stations across Australia. This study investigated the streamflow variability and inferred trends in water availability for those stations. The results present a systematic analysis of recent hydrological changes in Australian rivers, which will aid water management decision making.

We present a framework for assessing climate impacts on future low flows that combines different sources of information termed pillars. To illustrate the framework, three pillars are chosen: low-flow observation, climate observations and climate projections. By combining different sources of information we aim at more robust projections than obtained from each pillar alone. The viability of the framework is illustrated for four example catchments from Austria.