Effects of climate and land use changes on runoff extremes

This work proposes a modeling framework for the analysis of alterations in the watershed hydrological response and, more specifically, in runoff extremes, induced by climate change and urbanization. A weather generator and a cellular automata land-use change model are used to generate hypothetical scenarios accounting for relevant trends at the global scale. Such scenarios are successively considered to force a spatial-distributed hydrological model, which simulates, at high time-resolution, most of the key hydrological variables at the basin scale. The framework is applied to the Peatcheater Creek at Christie basin (OK, USA). The considered climate alterations are negative and positive variations in mean annual precipitation, obtained by different configurations of rainfall intensity and frequency, and simultaneous increase in temperature. Urbanization is conceptualized by an increase in the fraction of impervious areas within the basin. The analysis of the hydrological response simulated under the different scenarios, shows how the considered perturbations, acting separately or combined, may significantly alter the runoff generation mechanisms, resulting in relevant alterations of the extreme runoff events intensity and their associated return period.