Supplementing Missing Data Using the Drainage-Area Ratio Method and Evaluating the Streamflow Drought Index with the Corrected Data Set

Abstract

In water resources management, it is essential to have a full and complete set of hydrological parameters to create accurate models. Especially for long-term data, any shortcomings may need to be filled using the appropriate methods. Moving the recorded observed data using the drainage-area ratio (DAR) method to different points is considered one of these methods. The present study used data from six different flow observation stations in the Asi River sub-basin, known as the fertile agricultural areas in Turkey, and transferred the data to various other locations that already have existing observations. This study tested how close the values this method produced were to the actual values and investigated the question “how is missing data imputation improved by the determination of method bias coefficients?” to analyze the method’s accuracy, the streamflow drought index (SDI)—a hydrological drought index—was applied over a 12 month timescale. Contour maps were formed according to both the obtained index results by using the original data from the target station and the transferred streamflow data. As a result of this study, a severe divergence from the actual values was observed in the data directly transferred to the target stations in proportion to their area. The distance of the existing stations between each other produced a very high correlation coefficient, both in the direct transfer process and after the correction was applied. Similarly, in terms of drought index calculations, values close to 97% were seen in the original and transferred flow rates. Consequently, from the perspective of the effective management processes of water resources, the transportation of the data from basin-based observation stations corrected according to the drainage areas can be thought to positively affect the design stages and cost calculations for future water structures.