Discharge Estimation by Drainage Area Ratio Method at Some Specific Discharges for 2251 Stream Gauging Station in East Black Sea Basin, Turkey

Authors : Fatih SAKA, Hasan Törehan BABACAN

Pages : 22-25

View : 13 | Download : 12

Publication Date : 2019-08-31

Article Type : Research Paper

Abstract :Flow duration curves insert ignore into journalissuearticles values(FDC); showing exceedance probabilities across flow value frequencies at a specific time can be used for determining flow values having certain exceedance probability. But FDC has not been obtained at the place where flow measurements are not existed or insufficient, so discharges having certain exceedance probabilities have been estimated by different methods. In this study, drainage area ratio insert ignore into journalissuearticles values(DAR); method was considered due to obtaining discharge values at ungauged sites for feasibility studies. Three basins having similar hydrologic characteristics were chosen for this purpose. Discharges having %3, %20, %30, %50 and %90 exceedance probabilities were selected for the estimation. Three basins are 2251 streamflow gauging station insert ignore into journalissuearticles values(SGS);, 22-88 SGS, and 22-61 SGS in the Black Sea Basin, Turkey. The 22-88 and 22-61 SGSs are included in the area of 2251 SGS. If discharges having special exceedance probabilities need to be determined, firstly it is considered to investigate whether the DAR method can be used. DAR method is mainly depended on a regression analysis between the project site and the other basins/subbasins which have long-term data. %3, %20, %30, %50 and %90 exceedance probabilities on yearly scale discharges were obtained from 10 years of data from each SGS. Regression analysis was applied between flow records and drainage areas of the SGSs. Flows having exceedance probabilities of 3, 20, 30, 50 or 90 percent and their regression equations were analyzed and absolute relative error of them were investigated. After analysis, determination coefficients of discharges having %3, %20, %30, %50 and %90 exceedance probabilities were obtained as 0.898, 0.807, 0.834, 0.782 and 0.892, respectively. Mean absolute relative errors were 18.88, 7.28, 5.83, 2.14 and 1.53, respectively. According to discharges for the considered exceedance probabilities, errors can be dangerous level for %3 exceedance probability, but the other exceedance probabilities , DAR method can be useful for feasibility studies. Consequently, it has been found that errors of the DAR method can’t be convenient for all percent values of exceedance probabilities. Using for higher discharges having smaller exceedance probabilities can cause more errors.
Keywords : Drainage area ratio method, Flow duration curves, Regression analysis, Discharge estimation, Ungauged basins