Review the Efficiency of Empirical Relations on Estimating the Peak Flow Rate of Flood in Arid Areas of Central Iran

Flood, is a natural event, which every year causes severe and great life and property damages in the world, and also creates serious obstacles for social and economical development of the countries. Therefore, studying this phenomenon particularly estimating peak flow rate of flood and identifying the effective factors on it, has a great importance for mitigating its damages. In general, implementing empirical methods is one of the methods for estimating maximum flood in the basins with no hydrometric stations. Theses methods are based on one or more effective factors on formation of flood and sometimes is presented for special areas with particular physical and climatic conditions. Therefore, for using the said methods, the review and evaluation of their regional coefficients seems necessary. In fact, these coefficients reveal the impact of terrestrial and atmospheric factors in converting precipitation to runoff and creating peak flood discharge. This research tries to provide a more detailed analysis of Fuller empirical approach and its regional coefficient calibration in Central Iran basin. The importance of calibrating this approach is obvious since Fuller method is widely used in different parts of Iran to estimate maximum discharge as design flood for water related projects. So far, this approach has been used for designing Hydraulic structures in different parts of Iran, regardless of calibrating its regional coefficients.In this research, the 31 years statistics of ten hydrometric stations has been used in this basin in order to be calculated based on the moment flow rate quantities of flood in different return periods. statistical analysis at the first stage showed that the empirical method of Fuller in this wide climatic limit with the existing weak climatic quality has no appropriate efficiency. But the test results of Fuller's empirical in other climatic zones (semi-dry, semi humid and humid) implies a relatively high efficiency.. Langbyn homogeneity test (which is often used for determining the hydrologic homogeneous groups) based on the findings of this study did not show a high efficiency in central Iran.