Vulnerability Analysis of Flood in Rangelands Using Multi Criteria Decision Analysis and Geographic Information System (Case Study: Gilard Basin, Damavand, Iran)

Flood disaster is considered as a major natural hazard due to its devastating effects on the affected areas. Determining the flood vulnerable areas is important for decision makers in order to perform planning and management activities. Geographical Information System (GIS) is integrated with Multi Criteria Decision Analysis (MCDA) used to analyze the flood vulnerable areas. The aim of this research was to provide more flexible and accurate decisions to evaluate the causative factors for planning and management of rangelands of Gilard, Damavand. So, effective factors influencing flood occurrence in the study area was first surveyed. Some of the causative factors for flood in the watershed such as mean annual precipitation, basin area, basin slope, drainage density, land uses and soil type were taken into account. Then, through assembling spatial and descriptive information related to the study area and using Analytic Hierarchy Process (AHP), the criteria have been grouped and weighted. At the end, as regards of ultimate weight, the basin was classified into five classes. Results of this research show that mean annual precipitation and Sedimentation Rate with the average values of 26.5% and 2.01% had maximum and minimum effects on flood occurrence in rangeland of Gilard in Damavand, respectively.