A TOPSIS approach-based morphometric analysis for sub-watersheds prioritization of high Oum Er-Rbia basin, Morocco

Abstract

The study area covers 1871 km2 is located in the upstream of Oum Er-Rbia river basin, between latitudes 33° and 34° North, and longitudes 4°30′ and 5°20′ East. Watersheds prioritization based on morphometric parameters through the analysis of linear, areal and relief aspects is necessary in order to develop a sustainable watersheds management plan. The High Oum Er-Rbia basin has been subdivided into 17 sub-watersheds using remote sensing data (Aster-DEM) and Geographic Information System. For prioritization of sub-watersheds. The Multi-Criteria Analysis through the Technique for Order Preference by Similarity to Ideal Solution (TOPSIS), were applied to determine the relative weights of various parameters. Linear parameters; such as bifurcation ratio (Rb), drainage density (Dd), stream frequency (Fs), drainage texture (Dt), and shape parameters such as form factor (Rf), shape basin (Bs), elongation ratio (Re), compactness constant (Cc), and circularity ratio (Rc). The present study is an attempt to use TOPSIS approach based morphometric indices for prioritization of watersheds for water and soil resources conservation and management. The results show that sub-watersheds 2 and 6 have been ranked 1 and 2 assigned to highest closeness (C i + ) to ideal solution with 0.6838 and 0.6788 respectively. These sub-watersheds must be given the highest priority for soil and water conservation measures, to insure future sustainable agriculture, water quality and to prevent silting of Ahmed El-Hansali Dam.