Flash flood potential prioritization of sub-basins in an ungauged basin in Turkey using traditional multi-criteria decision-making methods

Morphometric analysis of watersheds based on morphometric parameters is the most widely accepted method for watershed prioritization. However, traditional methods adopted for prioritization of sub-basins lack a standard classification of the morphometric parameters and ranges of their values. So, in this study several multi-criteria decision-making (MCDM) methods and a number of traditional methods are used for watershed prioritization regarding the flash flood potential of the sub-basins. Akçay, a small ungauged basin in Turkey, was chosen as the study area, and 12 morphometric parameters were determined for the basin. The geomorphological instantaneous unit hydrograph concept coupled with Monte Carlo analysis was used to estimate the flood yield of the basin due to the lack of flow data. Kendall tau and Spearman correlation coefficient tests and receiver operating characteristics analysis were performed to validate the results of the traditional methods and the MCDM approaches for prioritization of the sub-basins. Results showed that the AHP method could well predict the sub-basins with higher flood potential, while the methodology adopted in the study to determine the criteria weights obtained from ANP method in MCDM improved the prediction capability of those approaches, especially VIKOR. The initial values of criteria weights were determined to be effective on the predictions and sensitivity analysis. When the results of traditional methods and MCDM approaches were compared, the MCDM approaches were found to give improved results. This study showed that MCDM approaches can be used to provide an efficient management of basins regarding conservation of water resources and soil.