Extracting and Evaluating Future Intensity-Duration-Frequency Curves of the Present Century Using Dynamic Time and Space Down-Scaling (Case Study: Rasht City)

One of the main goals of this research is to evaluate the changes in intensity-duration-frequency (IDF) curves under the effect of climate change in the future to show the necessity of adopting new methods in urban flood management. In this research, the dynamic method and the PRECIS regional climate model were used for spatial downscaling, due to the need for high accuracy in urban areas. The data generated by general and regional circulation models are too large in terms of temporal resolution to be used in the development of IDF for short-term precipitation. In this research, a special and two-step method was used to convert daily rainfall into short-term rainfall up to a resolution of 10 minutes. In this research in the city of Rasht, as representative of the Semi-Mediterranean climate, the IDF curves for the distant future (2070-2100) were produced and were compared with the curves in the near historical period to ensure using the data belonging to the first and second decades of the 21st century, i.e. after occurring the climate jump in the region. The results showed that for storms with a short duration of 10 to 60 minutes for all return periods, the intensity of precipitation increases significantly. Therefore, it is necessary to review the intensity-duration-frequency (IDF) curves to adopt new methods in urban flood management in Rasht City.