RESEARCH ON LAND COVER CHANGES IN SHIYANG RIVER BASIN IN RECENT 50 YEARS BASED ON RS AND GIS

The Landsat series satellite remote sensing data from 1970 to 2017 are adopted for basic data to study the land covers in the Shiyang River Basin by data processing and object-oriented information extraction. The transfer matrix and GIS approaches are used to analyze the temporal and spatial variation characteristics of different land types in Shiyang River Basin. The results show that:1) In the past 50 years, the natural oasis area in Shiyang River Basin has been decreasing year by year, from 35 917.53 km² in 1970 to 33 865.47 km² in 2017; and the area of artificial oasis increased correspondingly from 5 355.79 km² to 7 207.70 km². 2) The cultivated land, natural forest land, natural grassland and construction land show a generally increasing trend. The increased cultivated land is transferred mainly from natural grassland, unused land and wetland. The increase of natural forest land is mainly from natural grassland and unused land. The natural grassland area is increased mainly by the transferring of unused land. The construction land expands by taking up surrounding grassland, cultivated land and unused land. 3) The evolution of land types reflects the better ecological environment and increasing oasis area of the Shiyang River Basin.