Changes in vegetation and landscape patterns with altered river water-flow in arid West China

Landsat TM images of Tarim Basin in western China for 1986, 1999 and 2004 were analyzed for quantifying the patterns of landscape change relating to changes in water supply. Results showed that vegetation area and NDVI mostly decreased from 1986 to 1999, and increased from 1999 to 2004, while changes in desert area displayed an inverse pattern. Saline alkali soil showed a tendency of increase from 1999 to 2004. Spatially, percentage of vegetation area decreased and percentage of desert area increased with distance from the river in the upper section, while such patterns were not observed for both the middle and the lower sections. Landscape displayed a pattern of fragmentation from 1986 to 1999 and integration from 1999 to 2004. Shape of vegetation patches tended to become more regular from 1986 to 1999 and more irregular from 1999 to 2004. Our results indicated hydrological control of spatio-temporal variations of vegetation and landscape pattern in arid regions. Water diversion can be effective for raising the local groundwater level and improving plant growth, but its effect is largely restricted to areas adjacent to the water pathway.