Prediction of flow intermittence in Drying River Networks using a process-based hydrological model

Intermittent rivers and ephemeral streams (IRES) account for about half of the world’s rivernetworks and are considered to increase under climate change and growing anthropogenic wateruse. However, the hydrological mechanisms that control the spatio-temporal flow patterns in IRESand their effects on the expansion and contraction of stream segments are not fully understood.Discharge measurements mainly exist for gauging stations, which are often located downstream andin the rivers’ main stems. They are often less impacted by flow intermittence than headwaters andsmaller river channels. In consequence, impacts of climate change and anthropogenic alterations onhydrological process dynamics in IRES cannot easily be analysed, neither the influences of climatechange and human water use on IRES be quantified.Within the framework of the Horizon 2020 project DRYvER on Drying River Networks andClimate Change, we try to tackle this challenge by developing methods and tools using the JAMSmodelling framework and J2K model family to assess hydrological process interactions at highspatial and temporal resolutions, which include the scale of small reaches (about 50 ha catchmentsize). For that purpose, we developed process-based hydrological models for six mesoscaled riverbasins between 200 km² and 350 km² in different European countries (Croatia, Czech Republic,Finland, France, Hungary, Spain). At the same time, we used data from field measurementsand a citizens science application to validate our models at the reach scale. In this study weanalyse the ability of our hydrological model to represent observed temporal and spatial dynamicsof flow intermittence at high resolution, and develop adaptations that allows using these modelsin an upscaling step to estimate the impacts of future climatic changes and anthropogenic waterconsumption on flow intermittence all over Europe.