Study on Ecological Water Requirement of Vegetation in Wuhai Based on GIS

Abstract

Wuhai City is located in Inner Mongolia, belongs to the arid and semi-arid area of Northwest China, where precipitation is scarce, vegetation coverage is low and evaporation is large. With the exploitation of coal resources, the cultivated land area is gradually reduced and the surface is seriously damaged. After mining, a large number of mines and coal gangue piles are left behind, causing serious ecological problems. In order to ensure the normal growth of vegetation in Wuhai City, it is of great significance to study the ecological water demand of vegetation in Wuhai City for the realization of reasonable allocation of water resources, ecological restoration of mines and sustainable development of the city. Based on remote sensing satellite image data, combined with land use type map and ground meteorological data, this paper analyzes the spatial and temporal variation characteristics of normalized difference vegetation index (NDVI) in Wuhai City, calculates the evapotranspiration of vegetation in reference year, and obtains the ecological water demand of vegetation in Wuhai City by using area quota method according to different water demand spatial areas. The results showed that: in the total ecological water demand of vegetation in Wuhai City, the water demand of medium coverage grassland was the largest, reaching 407.59 mm, while that of forest land was the smallest, reaching 309.01 mm. The other water requirements from large to small are: low coverage grassland, high coverage grassland, sparse forest land, shrub land. Grassland accounts for 98% of ecological water demand, while woodland only accounts for 2%. The total ecological water demand is 326 million m3.