Land use and landscape pattern changes in the middle reaches of the Keriya River

Water is the main driving factor of oasis survival. Rivers play important role in maintaining the formation of ecological systems in arid regions. In this study, the spatial and temporal changes of land use/land cover and the landscape pattern in the middle reaches of the Keriya River were analyzed using the GIS technology through ArcGIS and Fragstats, based on remote sensing images from 1995, 2005, and 2015. A buffer analysis along the main river channel was conducted to analyze the spatial land use/land cover(LULC) characteristics and landscape patterns. A model was introduced to quantify the directions of LULC changes. The results were as follows: 1) From 1995 to 2015, cropland area increased by 6.44%, while grassland and water area decreased by 16.69% and 4.38%, respectively. Cropland expansion and water area degradation primarily occurred along the river, and grassland degradation was mostly noted in the oasis-desert ecotone. Along the river, cropland area was mainly converted from the water area and grassland, and the water area was mostly converted into cropland. In the oasis-desert ecotone, grassland was mostly converted into unused land. 2) The landscape pattern also changed obviously. Landscape fragmentation increased, and diversity of the landscape decreased, which occurred along the river and oasis-desert ecotone most obviously. 3) Results of the LULC change direction model showed that a LULC change along the river experienced a process of degradation and slight melioration. In the other areas, the LULC change experienced continuous degradation.