Simulating the spatio-temporal variability of streamflow response to climate change scenarios in a mesoscale basin

A continuous rainfall-runoff simulation was performed to assess the potential effect of climate changes on the streamflow regimes and water resources of tributaries of the Alzette river basin extending over 1176 km2, mainly in the Grand Duchy of Luxembourg, characterized by various hydrological patterns. Global climate change scenarios for the 2050 horizon, based on GCM projections from the KNMI and UKHI synoptic runs, were disaggregated into mesoscale daily PET and rainfall series. Seasonal expected PET changes were proportionally applied to present daily values, whereas future hyetographs were empirically constructed according to observed trends in rainfall time series for the study area. The various ways of applying the mesoscale rainfall scenarios exert a significant influence on the magnitude and spatial distribution of streamflow responses. The comparison of future and present hydrographs also shows that the impact of mesoscale climate change is extremely variable with regard to the considered hydrological variable. The spatial variability of streamflow responses is largely conditioned by climatic and physiographical characteristics of the sub-basins. The winter period is most affected by altered climate conditions and some sub-regions appear to be particularly sensitive in terms of changes in low or high flows.