development of a new integrated method for generation of idf curves based on three scenarios of climatic changes

Climate change can change the intensity-duration-frequency (idf) curves. this research evaluates idf curves changes of the baghmalek climatic station in iran’s southwest. developed integrated method extracts the idf curves using of the gumbel and log-pearson iii probability distributions and observed maximum annual precipitations. durations of these precipitations are 15, 30, 45 minutes and 1,2,3,6 and 12 hours.   for this purpose, this method utilizes the recorded precipitation data of the baghmalek climatic station in a 40-year period (1974-2013). then mean square error method determines the probability distribution that has the best fitting with this data. the hadcm3 prepares precipitation data for a 30-year period (2021-2050) based on a1b, b1 and a2 scenarios. also this method selects an optimum artificial neural network to extraction of maximum annual rainfall intensity for different durations and scenarios. then selected network and the chosen probability distribution produce idf curves for different return periods and scenarios. produced idf curves for different scenarios are compared to idf curves of base time period. because of increasing carbon dioxide and its greenhouse effects in these scenarios, rainfall intensity will increase for return periods less than 2.33 years while it will decrease for return periods more than 2.33 years.