بررسی تغییرات اراضی تحت تاثیر بیابانزایی به کمک سنجش از دور و سیستم اطلاعات جغرافیایی مطالعه موردی: بیابان سبزوار

Desertification is one of the difficulties which has been taken in to consideration in the world. The main objective of this study is: determination of lands affected by disertification using Remote Sensing and Geographic Information Systems, in Sabzevar. In order to meet this general objective: Satellite imagery of Landsat TM- 29 April 1987 and 13 May 2001 were selected and used, after haze and geometric correction. A large number of Principal Componentes (PC) and False Color Composit (FCC) were calculated, but FCC521:RGB was selected for background of classification because of the best correlation. The Satellite imageryies were classified by the maximum likelihood algorithm on the base of the field data. A study was conducted to determine the iso line of change in groundwater salinity and depth, in the study area, by using subsurface water data ( quality and quantity). The results showes that on non saline parts of the study area and in the area of gypsum the differentation is less in both maps. Also the area of land use is more or less the same in two classified maps except in new agriculture which increase of 3632 ha and in urban which developed of 672 ha. Merging and processing the whole data showes that the agriculture lands has increase from 1987 to 2001. More salinity and less depth of groundwater than their past, are the results of groundwater data analysis, specially in SE part of the region. Keywords: Desertification, GIS, RS, Salinity, Sabzevar.