Zoning flooding by using GIS (Case Study: Marjan and Khosban basins, Alborz province)

Development of remote sensing techniques in various fields of management has providedthe access to a large amounts of data in different fields of natural hazards management.Environmental planning and risk management are the cases that are done very well by theapplication of Geographical Information Systems (GIS). The damage caused by naturaldisasters such as floods has increased in recent years in Iran. In this paper, the effects ofgeomorphologic features on flooding were studied and compared by the comparison of thevariables effectiveness in basin, in Marjan and Khosban sub-basins of Taleghan basin inAlborz province. For this purpose, morphometric features of these two sub-basins include:area, watershed length, form factor, Elongation factor, main channel slope and time ofconcentration were studied, quantified and analyzed by Arc-GIS. The results show that therunoff height in Khosban sub-basin is more than Marjan’s and it is more productive aboutpeak discharge and runoff volume, structural measures therefore set in this area should bemore resistant. On the contrary, the reaction rate of runoff and flooding in Marjan sub-basinis shorter in duration. So it is necessary to do more investigations on effective parameterson flooding and flood-prone areas and the main factor that can make the greatest impact onflooding should be identified and management actions need to be taken.

Keywords:

Flooding , GIS , Khosban and Marjan basins , Peak discharge , Runoff