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 river
networks and are considered to increase under climate change and growing anthropogenic water
use. However, the hydrological mechanisms that control the spatio-temporal flow patterns in IRES
and 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 and
in the rivers’ main stems. They are often less impacted by flow intermittence than headwaters and
smaller river channels. In consequence, impacts of climate change and anthropogenic alterations on
hydrological process dynamics in IRES cannot easily be analysed, neither the influences of climate
change and human water use on IRES be quantified.
Within the framework of the Horizon 2020 project DRYvER on Drying River Networks and
Climate Change, we try to tackle this challenge by developing methods and tools using the JAMS
modelling framework and J2K model family to assess hydrological process interactions at high
spatial and temporal resolutions, which include the scale of small reaches (about 50 ha catchment
size). For that purpose, we developed process-based hydrological models for six mesoscaled river
basins 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 measurements
and a citizens science application to validate our models at the reach scale. In this study we
analyse the ability of our hydrological model to represent observed temporal and spatial dynamics
of flow intermittence at high resolution, and develop adaptations that allows using these models
in an upscaling step to estimate the impacts of future climatic changes and anthropogenic water
consumption on flow intermittence all over Europe.