Improving the flow duration curve predictability at ungauged sites using a constrained hydrologic regression technique

In this study, we proposed an improved streamflow regionalization technique to avoid the systematic errors associated with the existing techniques, such as the simple Multiple Linear Regression (MLR) and Stepwise Regression (SWR). We hypothesized that the proposed Constrained Hydrologic Regression Technique (CHRT) would be more robust, consistent, and accurate than the MLR and SWR. Cross validation was also conducted in order to verify how the proposed CHRT was a feasible tool, along with the SWR and Principal Component Analysis (PCA) based regression. The predictive performances of the proposed method were evaluated using the Leave One Out Cross Validation (LOOCV) procedure and other evaluation criteria, such as the Nash-Sutcliff coefficient (NASH), Root Mean Square Error (RMSE), and the adjusted coefficient of determination (R (adj) (2) ). The results indicated that for the CHRT, SWR, and PCA, the average NASH values were 75, 58.16, and 65.23 respectively based on performance measures. Therefore, it is noted that the CHRT is a significant method for prediction of the Flow Duration Curve (FDC) as compared to contenders. Hence, the CHRT could be a more promising tool for the hydrological prediction at ungauged basins.