Climate model outputs can be used to assess the expected behaviour of extreme precipitations in the future due to climate change. In Europe, the EURO-CORDEX project provides precipitation projections in the future under various representative concentration pathways (RCP), proposed by the Fifth Assessment Report (AR5) of the IPCC. The EURO-CORDEX project regionalised Global Climate Model (GCM) outputs in Europe through a set of Regional Climate Models (RCM).
In this work, 12 combinations of GCM and RCM under two scenarios (RCP 4.5 and RCP 8.5) supplied by the EURO-CORDEX programme are analysed in the Iberian Peninsula. Annual maximum daily precipitation series are considered. Precipitation quantiles for a set of probabilities of exceedance are estimated by using the three-parameter Generalized Extreme Value distribution and L-moments. Precipitation quantiles expected in the future are compared with the precipitation quantiles in the control period, for each climate model. Delta changes in precipitation quantiles are obtained as thresholds exceeded by a percentage of climate models: 50%, 68% and 90%. Three periods in the future are considered: 2011-2040, 2041-2070 and 2071-2100.
An approach based on Monte Carlo simulations is developed, in order to assess the uncertainty from the climate model projections. Expected changes in the future are compared with the sampling uncertainty in the control period. Thus, statistical significant changes are identified. The higher the significance threshold, the fewer cells with significant changes are identified. Consequently, a set of maps are obtained for various thresholds, in order to assist the decision making process in subsequent climate change studies.
The results of this study are currently being applied to implement the Floods Directive in Spain, regarding the preliminary assessment of flood risks.
Annual maximum daily rainfalls will change in the future because of climate change, according to climate projections provided by EURO-CORDEX. This study aims at understanding how the expected changes in precipitation extremes will affect the flood behaviour in the future. The expected changes in precipitation extremes cannot be transformed directly into changes in runoff, as for a given rainfall event, the flood magnitude depends on the initial moisture content in the catchment, which in turn also depends on precipitation and temperature in the days before its occurrence. Therefore, hydrological modelling is required to characterise the rainfall-runoff process adequately in a changing climate to estimate flood changes.
Precipitation and temperature projections given by climate models in the control period usually do not fit exactly the observations in the same period from a statistical point of view. To correct such errors, bias correction methods are used. This paper aims at finding the most adequate bias correction method for both temperature and precipitation projections, minimising the errors between observed and simulated precipitation and flood frequency curves.
Four catchments located in central western Spain have been selected as case studies. The HBV hydrological model has been calibrated, using the observed precipitation, temperature and streamflow data available at a daily scale. Daily rainfall and temperature projections for RCP 4.5 and 8.5 provided by EURO-CORDEX have been used.
The results have shown that the correct calibration of some parameters of the HBV model is essential to obtain coherent results, mainly those related to surface runoff generation. In addition, soil moisture content at the beginning of flood events affects flood magnitudes. Consequently, expected changes in precipitation extremes are usually smoothed by the reduction of soil moisture content due to expected increases in temperatures and decreases in mean annual precipitation. Because of this the rainfall is the most signifcant imput to the model and the best bias correction is quantille mapping polynomial.