The Estimation of Surface Run off in Rasht City and Case study Shahid Gholipoor Avenue to the Yakhsazi Square

In this research after supplying the data and TIN for a restricted area that was studied separately we studied land efficiency situation in georefrenced polygons with conformity of the city network on paths and streets along with the physiographics characteristic of the urban drinage? Runoff depth and flood water capacity of the 17 fold sub basins with different return periods were calculated using SCS and deductive approach. They did not show good efficiency because of shortness of the basin. The infiltration severity and the flood waters of the immediate approximation with different return periods was considered as dependent variables The impenetrable city basins and the changes across the city and changes due to development, as well as destruction of vegetation cover, soil compaction and the establishment of surface water systems that reduces water infiltration in the soil. Runoff depth and flood water capacity with the different returns were calculated through SCS and deductive approach. The research showed that there is a positive correlation between the maximum peak discharge and the rate of precipitation. Also there is a strong correlation between the maximum peak discharge and the maximum of intensity precipitation in 24 hours. By using the geographic information system (GIS) we drew topographic maps, soil and plant cover maps. Through preparing the maximum rainfall table in 24 hours and using the curve number (CN) formula and soil conservation service (SCS) model.The main object of this research was to determine the role of human factors, such as house or road, construction and the removal of plant cover and natural areas, on floods and also present some suggestions for solving flooding problems focusing on Shahid Gholipoor Avenue to Yakhsazi square of Rasht.