Impact of Climate Change on Intensity-Duration-Frequency Curves of Precipitation (Case study: Babolsar station)

Climate change is effective on the amount of precipitation in all areas and consequently it is effective on IDF curves. The aim of this study is the evaluation of effects of climate change on IDF curves in Babolsar station in future period since 2011 to 2030 using atmospheric general circulation model and under emission scenarios. In this respect، two appropriate statistical distributions، the Gumbel and Log - Pearson Type III، were fitted with hourly rainfall values between 1998-1966. Then IDF curves have extracted For intervals of 10، 20، 30 min and 1، 2، 6، 12 and 24 hours and return periods of 2، 5، 10، 25، 50 and 100 years. Next، data in daily time scale were estimated for intervals of 2013-2030 using atmospheric general circulation model of HadCm3 under emission scenarios A1B، A2، B1 and down scaling model of LARS-WG. The derivative curves of assumption scenarios have extracted by modified relationships of Bell. The results indicate that the values of correlation coefficient in Gumbel distribution were in the range of 0. 996-0. 998 and for Log - Pearson Type III، they were in the range of 0. 969-0. 974 that shows more significant correlation for Gumbel distribution. Comparison between rainfall predicted by the scenario mentioned and rainfall calculated by Gumbel distribution for data from 1966-1998 is showed an increase in precipitation intensity for BABOLSAR station in future periods (2 - 2011). For example، according to three scenarios A1B، A2، B1 the rainfall value for interval of one hour and return period of 2 year، respectively، 28%، 17% and 25% have increased than the values of basic rainfall.