DETECTION OF LAND-USE/COVER CHANGES OVER CHAHNIMEH IN IRAN USING LANDSAT TM IMAGES

摘要

Climate change, particularly the recent drought and excessive human exploitation of geo-environmental resources, has caused rapid changes in land-use and ground cover in many south-east areas of Iran. This study classified land-use/cover detection using a combination of multi-spectral and hyper-spectral images as innovative change detection techniques in the ChahNimeh water reservoir of Iran. The intensity of change was determined for the periods 2000-2010, using multi-temporal Landsat TM and field-visits in 2010, in which a combination of post-classification comparison and image ratio methods were used. Visual interpretation of false-color composites and hybrid supervised classification method integrated with GIS analyses were used to generate land-use/cover maps. The results showed that vegetation and salty land decreased, while bare land and shallow-water areas increased. Changed areas accounted for 46.5$ of the total area. Conversions from and to salty lands, shallow water level and bare lands were by far the most extensive changes. Shallow water level and bare land increased, while salty land and vegetation land areas decreased in the 10-year period between 2000 and 2010. Four classes of qualitative changes were recognized based on land-use detection; The Type I change indicated changes in water level from deep water to moderate and shallow levels due to reduced water output from Hirmand, and a lower water depth in the ChahNimeh reservoirs. Vegetation cover was decreased. The Type II changes mainly transpired within vegetation lands. The Type III changes included changes from vegetation to salty lands. Transformations between salty lands to bare land were typical of Type IV changes. Detecting and monitoring of these changes are discussed in relation to the management of this important shelter for wintering migratory birds.