Modeling flood flow of Jajrood Basin River

Flood is natural phenomena. That human social accept it، is inevitable. But the reason of occurrence، size، and repetition is multifactor that change condition region of climatology، natural and geographical. Obviously the reason of flood is precipitation. But studies show there is not liner relation with this factor. As such disruptive this relation in additional to geographical condition has physical properties of basin and is properties of hydrologic. The case study of this research is located northeast of Tehran. It located in the east longitude from 51o 22’ to 51o 52’ and north latitude from 35o 45to36، 50. In this research for modeling of flood flow of Jajrod river basin first effective indexes in flooding with use of experience past study and special traits of basin recognized that superlative indicator effective in flooding region has been characterized and proportion of each sub basin was characterized. Ultimately، with the use of multiple regression method (enter method) the flooding model of basin was produced. Required layer for evolution with use of GIS software was produced. Conclusion of research shows in physiographic properties of studied، invoices of ratio of figure، ratio of density، time concentration، basin surrounding، sum of length of river، length of first class River modeling of flooding has maximum importance.