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 devastatingeffects on the affected areas. Determining the flood vulnerable areas is important fordecision makers in order to perform planning and management activities. GeographicalInformation 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 moreflexible and accurate decisions to evaluate the causative factors for planning andmanagement of rangelands of Gilard, Damavand. So, effective factors influencing floodoccurrence in the study area was first surveyed. Some of the causative factors for flood inthe 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 anddescriptive 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 ultimateweight, the basin was classified into five classes. Results of this research show that meanannual 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 inDamavand, respectively.