Predicting flow intermittence in France under climate change

Abstract

As climate changes, perennial headwater streams could become intermittent and intermittent rivers could dry more often due to more severe droughts. A modelling framework supported by field observations was applied to assess the probability of drying in headwaters at the regional scale (P D) under climate change. Empirical relationships between severity of low flows and observed proportions of no-flow states have been calibrated for 22 hydro-ecoregions under present conditions. These relationships were applied using daily discharge data on a large set of gauging stations simulated by the Modèle du Génie Rural à 6 paramètres Journalier (GR6J) hydrological model under Representative Concentration Pathway (RCP) RCP2.6 and RCP8.5 emission scenarios. The results suggest a more contrasting spatial pattern in the future than under current conditions. Noteworthy changes include increases in drying extent and duration, particularly in regions with historically high probabilities of drying and changes in seasonality in Alpine regions. Aquatic ecosystems will experience unprecedented hydrological conditions, which might lead to losses of ecosystem functions.