Evaluate the Flood Potential of the Hydrologic units in order to Control Flood using RS and GIS (Case Study:Watershed of Birjand City)

Flood is a natural Phenomenon that several factor has been caused it by event, size and repeat that it changes depending on Climatic conditions, natural and geographical area.One of the most important intended actions in the management of flood projects, Evaluation of the various sub basins participation in a Basin watershed in determining of various Component of the flood outlet in the basin. This study performed by GIS in order to calculate the runoff of the shahrood's watershed and the Soil Conservation Service model.For this research the shahrood’s watershed area of birjandcity was selected and after estimating the concentration time each watershed within kerpich method, the intensity of rainfall in returning period 25,50,100 of the year was calculated and By using the Rossmiller method the flow coefficient of flood was determined in the shahrood's watershed and the potential of each watershed were determined towards generating runoff and flooding. The results indicate that the potential runoff In the highlands bordering of this watershed that have a much slop and Geological formations of a hard type, has a large quantities and the highest potential level of flood rise. Because the reason that was in the shahrood's watershed the general slop towards the area of the city and this river is watershed drainage. the watersheds kh1 and kh3 have the Maximum flood ratio and the watershed kh6 has less ability than other watershed in order to produce runoff. Development of urban areas in the examined watershed has been the effective factors in increasing the potential of the flood and also provided by using weighted model in the calculation of the curve number that all the effective factors were considered in producing runoff and obtained more accurate estimate of runoff caused by rainfall in result and in order to do it seriously and Principles of prevention and in order to reduce the risk caused by flooding in the area shall be placed in working order.

کلیدواژه ها:

Flooding ، Runoff ratio ، estimation runoff ، Intensity of rainfall ، curve number ، Shahrood