Prioritizing the Construction of Watershed Check dams using spatial multi-criteria evaluation model (Case study: Dorahan watershed)

Identifying the appropriate places for implementing various management actions in the watershed is a challenging issue. Multi-Criteria Analysis (MCA) is an approach to assist managers in solving this problem. This study aimed to determine appropriate places for gabion check dams, earth embankments, and stone and mortar dams using the MCA technique in the Dorahan watershed in Chaharmahal and Bakhtiari province. First, a criteria tree was developed to integrate some ecological maps (flooding, erosion, channel number, slope, and geomorphology) with economic variables (distance to villages and roads) and spatial restriction variables (stream order, slope, geomorphology, and elevation). Analytical Hierarchical Process (AHP) was used to compare and weight the variables and management options. The eigenvalue vectors were measured for all criteria used in AHP. According to the AHP, the eigenvalues of flooding and erosion as the most important variables were 0.36 and 0.32, respectively. The management options against all criteria were then compared and earth embankment with an eigenvalue of 0.494 was recognized as the best management option in the watershed. Stone and mortar dams and gabion check dams were the two later management options with eigenvectors of 0.316 and 0.126, respectively.  All criteria maps were produced in a raster format by ILWIS software and were then imported into the Spatial Multi-Criteria Evaluation (SMCE) model. The appropriate areas for the construction of these management options (different kinds of small dams) were then mapped in the watershed. Sub-watersheds 6 and 7 were identified as the most suitable area for implementing these management options. A similar approach can be used to identify the best management practices for suggesting other bio-mechanical projects.