Assessment of the Estimation Methods of Flood Peak Discharge in Urban Catchment for Controlling Flood

With the increasing development of cities and changing the agricultural and pasture land use into residential and industrial lands, plus the parallel flood crisis in urban areas, the created changes in infiltration, runoff deviation, evaporation and transpiration lead to abnormal and irregular hydrological behavior of the urban watersheds toward the natural basins. Many factors influence emerging floods and their intensity, and studying them requires more comprehensive research works. For this purpose, in many small watersheds there is a need to select appropriate methods due to the basin conditions and features because of the lack of hydrometric station and many statistical flaws. This research aims to study and assess the peak discharge of flood in Birjand’s watershed. For this purpose, the hydrological method of rainfall- runoff and empirical methods were used. In this article, for zoning the model, the data of 11 hydrometric stations near the studied area were used. Then, the HYFA software was used to obtain proper distribution and calculate the discharge with different return periods in the area; and the maximum discharge amounts of floods in the similar basins without statistics were calculated in different return periods. The results from empirical methods indicate that these methods do not provide acceptable results and are not suitable for the studied stations, while hydrologic model of rainfall-runoff has acceptable results.