Report on downscaling global climate projections for catchment-scale hydrological modelling
Résumé
Intermittent rivers and ephemeral streams (IRES) account for more than half of the world's rivers.
However, few studies have investigated the evolution of IRES under climate change. Aiming to
overcome this problem, DRYvER proposed to provide daily hydrological projections, daily flow
conditions and flow intermittence indicators in 6 European Drying River Networks (DRNs).
The current work aims to produce reach-scale daily hydrological projections available for the period
1985-2100 for each DRN. To this end, coarse spatial resolution daily projections from Global Climate
Models (GCMs) are downscaled to obtain high resolution projections over the period 1971-2100.
Secondly, the high-resolution projections are used as input to the JAMS/J2000 model to obtain daily
catchment-scale hydrological projections. Several GCMs are used as well as 3 shared socio-economic
pathways (SSPs) to capture the uncertainty due to climate modelling and greenhouse gas emission
scenarios.
The results show that the methodology is able to reproduce the historical hydrological behaviour of
the DRNs in terms of seasonality, with some difficulties in Morava and Vantaanjoki regarding summer
discharge. Regarding the future periods, the responses of the six catchments were clearly different,
showing an impact of climate change closely related to their location. Spring, summer and autumn
discharges show a decrease for all catchments and all SSPs considered. For winter discharge, two of the
catchments show a slight increase, but the other four also show a decrease of varying intensity.