From regional climate simulations to the hydrological information needed for basin scale impact studies

摘要

The accuracy of local downscaling of rainfall predictions provided byclimate models is crucial for the assessment of climate change impacts onhydrological processes because the presence of bias in downscaledprecipitation may produce large bias in the assessment of soil moisturedynamics, river flows, and groundwater recharge.In this study, the output of a regional climate model (RCM) is downscaledusing a stochastic modelling of the point rainfall process able toadequately reproduce the daily rainfall intermittency which is one of thecrucial aspects for the hydrological processes characterizing Mediterraneanenvironments. The historical time-series from a dense rain-gauge networkwere used for the analysis of the RCM bias in terms of dry and wet dailyperiod and then to investigate the predicted alteration in the localrainfall regime. A Poisson Rectangular Pulse (PRP) model (Rodriguez-Iturbeet al., 1987) was finally adopted for the stochastic generation of localdaily rainfall as a continuous-time point process with forcing parametersresulting from the bias correction of the RCM scenario.