The Estimating of Shower and Forming IDF Curves in the West of Gilan Province (Case study: The Rasht, kharjegil and Estoor stations)

Regarding to the great significance of the showers in the repelling of the surface water in cities and also other instances, throught this research first we tried to gather some statistical information about the amount of the showers which have been fallen across the three stations of Rasht, Kharjegil and Estoor for 15 years. These data were collected from the archives of the organization of water resources. Then we did statistical calculations on the data of the showers and at last we applied the Smada software to distribute different fittings and making some basic equations for estimating the amount of the shower on the basic of their time intervals.The result of this research shows that in the most cases the data through the Gumble distribution of the extreme of type I and in some trivial cases through the log Pearson distribution of type III have better fitting than other ones. Also estimated equations for the showers are logarithmic 2 and 3; meanwhile, the correlation coefficient between duration and intensity in all cases was estimated more than 0/99. Furthermore we demonstrated that the curves of intensity, duration and frequency (IDF) through time and place scales can change regarding to the return period of the plan. Hence forming the models of estimating the shower in these zones are essential to plan and perform some of the urban development projects which directly are connected to this issue.