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

Öz

Flow duration curves (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 (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 (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.

Anahtar Kelimeler

• Drainage area ratio method,Flow duration curves,Regression analysis,Discharge estimation,Ungauged basins

Kaynakça

1. Ryu, “Developing homogeneous sequences of river flows and performing comparative analyses of flow characteristics,”Ph.D. thesis, Texas A&M University, 2015.
2. Saka, “Determination of synthetic flow duration curves by using mathematical methods and a case study in the eastern black sea,”Ph.D. thesis, Graduate School of Natural and Applied Sciences, Karadeniz Technical University, Turkey (in Turkish).
3. M. Sivapalan, K. Takeuchi, S.W. Franks, V.K. Gupta, H. Karambiri, V. Lakshmi, X. Liang, J.J. McDonnell, E.M. Mendiondo, P.E. O'Connell, T. Oki, J.W. Pomeroy, D. Schertzer, S. Uhlenbrook and E. Zehe, “IAHS decade on prediction in ungauged basins (PUB), 2003-2012: Shaping an exciting future for the hydrological sciences,” Hydrological Sciences Journal, 48.6: 857-880, 2003.
4. Farmer, “Estimating monthly time series of streamflows at ungauged locations in the united states,” MEng. thesis, Department of Civil and Environmental Engineering, Tufts University, 2012.
5. W.H. Farmer and R.M. Vogel, “Performance-weighted methods for estimating monthly streamflow at ungauged sites,” Journal of Hydrology, 477, 240–250, 2013.
6. D.G. Emerson, A.V. Vecchia, and A.L. Dahl, “Evaluation of drainage-area ratio method used to estimate streamflow for the Red River of the North Basin, North Dakota and Minnesota,” US Geological Survey Scientific Investigative Report 5017, 2005.