Evaluation of the ecological capability of Aqujan watershed for rangeland and agriculture using GIS

Evaluation of the ecological capability of the land is an intermediate stage of the land planning process, which the most appropriate land uses are determined for an area. So these studies which require investigation in locations from different perspectives are necessary for sustainable development. The purpose of this study was to determine the capability and suitability of lands for agricultural and rangeland uses and also to determine the area of unauthorized land uses of the Aqujan watershed of Qazvin province. The maps of the ecological resources of the watershed (including precipitation, elevation, slope, land units (soil depth and texture), vegetation, and erosion) were prepared and crossing in a GIS environment, the homogeneous environmental map units (work units’ map) were obtained. The ecological potential of watershed lands was determined by comparing the characteristics of ecological homogeneous units with the ecological model of agricultural and rangelands. Finally, the area of unauthorized land uses was determined using overlaying the current land use map and the land use map derived from ecological capability. The results showed that 3188 ha (44%) of the area is occupied by unauthorized land uses. The contributions of unauthorized livestock and range management, irrigated orchards and cultivations, and dry farming land uses were 2569 ha (34.9%), 211 ha (2.8%) and 408 ha (5.5%), respectively. The results of this study showed that there is a big difference between the proper and current land uses in the Aqujan watershed, which indicates the degree of deviation from the principles of sustainable development.