Abstract:

Variation of vegetation is one of the important indices for regional eco-environmental condition, and the secular vegetation change can reflect the variation regulation of the eco-environment with time. Based on MODIS NDVI, this paper studied the variation trend of vegetation index in the years of 2000 to 2004 in Ningxia area using quantitative remote sensing technique and slope method. According to the result, due to the reduction of diverted water volume from the Yellow River, the NDVI in some of the area became decrease from 2000 onwards. On the basis of the above research, the vegetation variation and different influence factors in some areas, such as Helan mountain, Liupan mountain, Hongsipu area and Yinchuan plain, were analyzed. The vegetation of Helan mountain and Liupan mountain areas were mainly controlled by the precipitation, and the vegetation degradation of Hongsipu area was strongly affected by the unreasonable utilization of water resources and was the result of soil salinization. The decrease of diverted water volume from the Yellow River and the groundwater overdraft were the main influence factors for the vegetation degradation in Yinchuan plain.

Key words: MODIS NDVI, slope method, groundwater, diverted water volume from the Yellow River, Ningxia