Assessment of climate change impact on floods using weather generator and continuous rainfall-runoff model

One of the potential impacts of climate change (CC) is the change on flood frequency and magnitude. Assessment of impact on floods involves many uncertainties. Difficulty in preparing reliable continuous time series of climate variables with fine time step and capturing extreme rainfalls for future climate scenarios has led to limited studies aimed at investigation of the change of flood regime due to CC. Weather Generators (WGs) have the potential for downscaling of GCMs (General Climate Models) outputs. However, WGs inabilities in relation to producing extreme rainfalls and low-frequency variabilities have caused WGs to receive limited attention in flood studies. In this study, a new WG model, that removes the aforementioned WGs' inabilities, is coupled with a continuous daily rainfall-runoff model to assess the CC impacts on floods of a basin in Iran. Changes in different characteristics of climate variables are applied in the downscaling procedure. Results indicated that, aside from the large uncertainty of emission scenarios, the climate change will lead to considerable increase in flood magnitude in the study basin. Copyright (c) 2011 Royal Meteorological Society