额济纳植被覆盖变化及对地下水埋深的响应

Vegetation Cover Change and Response to Groundwater Depth in Ejina Area

利用MODIS卫星遥感数据,建立了1998—2015年额济纳地区植被覆盖时空数据集,借助Mann-Kendall趋势检验和地统计学分析等方法,探讨了额济纳地区植被覆盖时空分布特征及其动态变化规律,揭示了研究区植被覆盖变化对地下水位埋深的响应机制。结果表明:1998—2015年额济纳地区年平均归一化植被指数(NDVI)为0.072～0.089,从年际变化特征看,额济纳地区NDVI值呈波动性上升趋势,从空间分布特征看,额济纳地区NDVI值的空间分布格局呈现斑块状分布;从地下水位埋深空间分布特征看,沿河流流向,东河、西河地下水位埋深呈现先增大后减小的变化趋势。

In this paper, using MODIS satellite data, a temporal-spatial data set of vegetation coverage for Ejina Oasis was established from1998 to 2015. With MannKendall trend test and geostatistical analysis, the spatial-temporal distribution pattern and dynamic changes of veg-etation cover in the Ejina region over the past 18 years were explored and the response mechanism of vegetation cover change to groundwaterdepth in the study area was revealed. The results show that the average NDVI of the Ejina region is between 0.072 and 0.089 during the peri-od of 1998-2015. From the perspective of inter-annual variations, the NDVI values in the Ejina region show a fluctuating upward trend.Since the implementation of the watershed policy in the Heihe River basin, the vegetation coverage in the Ejina region has gradually increasedand the oasis vegetation has been restored. From the spatial distribution characteristics, the spatial distribution pattern of NDVI values in Eji-na area is patchy. From the spatial distribution characteristics of the depth of the groundwater, along the river flow direction, the depth of thegroundwater in the east and west rivers shows a trend of increasing first and then decreasing. The growth and development of vegetation in theEjina area are controlled by the depth of groundwater.