Identification of Flood Prone Areas Using Geological Formations in Watershed Shahroud in Birjand

Flood is a natural phenomenon whose occurrence, severity and frequency depended on several factors which change due to climatic, natural and geographical conditions of each zone. The importance of understanding water resources and lack of acceptable network of hydrometric stations indicate the necessity of use of indirect methods to calculate runoff volume. The Shahroud watershed extends from the north highlands of Birjand to the eastern domain of highlands and in terms of the country’s watershed division it is considered as a part of the Loot watershed. The main reasons for increased flooding in the Shahroud watershed are changes in natural land use, illegal construction of buildings upstream of the watershed and illegal construction of buildings near the canals in recent years. In this research, the surface storage parameters of the watershed are determined based on geological maps and identification of material and kind of watershed stones. Then a map of areas prone to flooding is prepared based on the watershed geologic, petrology, hydrology and hydrogeology parameters. Based on the results of this study, only four cubic Kilometers from the whole watershed (0.25 percent of the whole watershed) are regions with low flooding potential and 1344 cubic Kilometers from the whole watershed (84 percent of the whole watershed) are regions with high and very high flooding potential. Therefore, identification of the areas of the Shahroud watershed that are prone to flooding could help in terms of soil conservation and reduction of flood damages and provides the possibility of proper management of the watershed.