Study On Dynamic Changes Of Desertification In Wutongwozi, Mulei County, Xinjiang Province

In this thesis, researches on vegetation, salinization and shallow groundwater in Wutongwozi coalmine area in Xinjiang Province are separately presented before final evaluating desertification. After analysis of annual variation from 2000 to 2012 on vegetation and its impact factors by using MODIS, DEM and meteorology data, the overall vegetation growth shows an increasing trend although the average NDVI in this area is very low. Also, vegetation is found to have positive correlation with relative humidity, previous precipitation and altitude, which shows an appropriate growing range between 1640 m to 1830 m. In the study of salinization, TM data of year 1989, 2000 and 2010 were used with decision tree to interpret saline soil. The result shows a low degree of salinization with no more than 2% saline soil. Area of salinization in 2010 is the largest whereas in 2000 is the smallest. This change is speculated to have relations with variation of temporal precipitation, annual precipitation and temperature. Due to the lack of groundwater information, this thesis used Analytic Hierarchy Process method to assign weights on slope, relief amplitude, flow accumulation, saline soil and vegetation to finally predict possibility distribution of shallow groundwater. The whole area shows a deficient shallow groundwater resource with only 2.56% area of most probable region and distributes mainly in northern salt pool, middle gullies and around surface water. In order to evaluate desertification in this area, fractional vegetation cover was used as major factor and to classify desertification degree from 2000 to 2012. Variation rates of these lands and their changes show some improvements on environment. However, other two factors – salinization and shallow groundwater implies a contrary situation. After analyzing the correlation between salinization and NDVI, saline soil proved the restriction effect on NDVI, especially when salinization was exacerbated. Similarly but differently, the increase in probability of shallow groundwater indicates a growing trend in NDVI but the deficiency of shallow groundwater had already proved. Therefore, although the study area showed an improvement in desertification, the rapid increasing salinization and shortage of shallow groundwater would restrain development in this area.