Classification of ecological capability of Hesarak watershed using multi criteria evaluation and GIS methods for forest expansion

Human activities, with increasing population of Tehran created a lot of environmental problems in this city. According to the functions of forests, afforestation can be adjusted to these problems. The objective of this research was to assess the ecological capability for afforestation in the Region of Hesarak, Tehran province. After identification of the ecological factors included the physical (physiography, topography, pedology etc.) and biological factors (vegetation area), the maps are prepared and then integrated using geographic information system (GIS). The result of integration was a layer of information unit, whose absolute limitations in each index were specified and then they were omitted from the assessment process using Boolean logic. The assessable area of the remaining district after omission was 843.8 Hectares which had a relative limitation and studied by multiple attribute decision making method. In the multiple criteria decision making method, the values were changed into qualitative values using bipolar interval scale. The weight of the criteria was designed through analytic hierarchy process method using pair compared matrix and was specified using skilled experts’ advices. At the last stage the final value was calculated using simple additive weighting method. Then the ecological capability of the area without limitation (843.8 he) was divided in 4 classes. The positioning of the forest development concluded from the four classes, by the multiple attribute decision making method was performed: The planning for the forest development was made for classes 1 and 2 with a total area of 489.17 Hectares.