Prioritization sub-watershed of Acemangar Basin in Chaharmahal-e- Bakhtiari for soil and water management using morphometric parameters and ensemble of TOPSIS-multivariate linear regression algorithm

Sub-watershed prioritization is very important in natural resources and watershed management. This study deals with prioritization of sub-watersheds using a mixed multivariate linear model of New TOPSIS-Regression over morphometric parameters of 11 sub-watersheds. Morphometric parameters include constant of compression ratio, roundness factor, form ratio, slenderness ratio,channel maintenance, drainage density, ruggedness number, The frequency channel, slope, drainage texture rate, The roughness rate, branching ratio and channel length were weighted using multivariate linear regression and observed flood events. Prioritization was performed by TOPSIS decision Method. Results obtained from weighting analysis showed that branching ratio, form ratio and ruggedness number have the most effect on flooding with 0.612, 0.221, and 0.212 scores, respectively. According to the results of prioritization, 4, 6 and 9 Sub-watersheds with the least distance to the positive optimum (0.0062, 0.051, and 0.048, respectively) and maximum distance to negative optimum (0.1734, 0.1809, and 0.1746, respectively) have the highest flooding intensity with maximum scores of 0.7365, 0.7777, and 0.7841, respectively, that should be prioritized for action management and watershed management. In order to validate the results, special deposition and sediment delivery ratio  ​​(SDR) was calculated for each Sub-watershed by PSIAC method using nine parameters including geology, climate, soil, water, topography, land cover, land use, surface erosion and river erosion. Validation of results indicate that the morphometric parameters and  used model has a high performance of prioritization of watersheds prone to flooding and high sediment production;  so that 4, 6 and 9 Sub-watersheds have the highest amount of Special deposition 97.1, 80.2, 70.1 Ton/Hec/Year and sediment delivery ratio 57, 55, and 59 percentage, respectively. The results of this study can be used in watershed management.