COMPARISON AND MODIFICATION OF RUNOFF ESTIMATION EMPIRICAL METHODS USING HYDROMETRIC STATIONS OBSERVED DATA (CASE STUDY: THE POLECHEHR WATERSHED- THE GAMASIAB RIVER), IRANGelavizh Moradi and Fariborz Yosefvand
Runoff estimation due to the rainfall is one of the most important issues in analyzing hydrology and water management problems. Using of empirical models in order to estimate the annual runoff in basins which are without hydrometric stations has always been recommended in hydrological studies. The main aim of this study is providing the best method using empirical methods for calculating the runoff estimation by determining the modification coefficient of these methods. To this end, the Polechehr hydrometric station which is one of the main branches of the Karkhe River has been selected and 8 relationships developed in different parts of the world have been used. These methods include the D, Souza, Irrigation Department of India, Turc, Kutayn, Khuzela, Agriculture Research Association of India, Justin and Lacey relationships. For statistical comparison of estimation methods with calculated runoff, the statistical indices such as RMSE, the mean difference and BIAS have been used. According to the obtained results in the Polechehr hydrometric stations, the most suitable method is the method of Agriculture Research Association of India (ICAR) and the worst method is the Khuzelamain coefficients. Although in the modified relationships the ICAR method is introduced as the best method, the other methods evaluation criteria (except the Justin method) does not have any difference with these methods. Therefore, these methods are applicable, too.
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