In order to probe the ecological groundwater table along the mainstream and in the downstream tributary-intensive areas of Ejina River, GPS, RS and GIS technology were applied to analyze the interactions between ground water table and different plant communities based on the data of observed long-term groundwater tables. The single point method was used in analysis of east-west river mainstream areas and west river downstream. The method of overlay between the groundwater table and the plant communities was used for analyzing east river downstream tributary-intensive areas. The results showed that the ecological ground water table was changed in different areas. It was estimated as 2.14 to 2.27 m in the east-west mainstream areas with a variable range of 0.61 to 1.14 m, 2.52 to 3.88 m in the west river downstream areas with a variable range of 0.90 to 1.09 m, and 2.48 to 3.39 m in the northern Andou Grassland areas with a variable range of 0.26 to 0.33 m. The different ground water depth associated with different plant communities in the tributary-intensive areas of the downstream of east river. Populus euphratica community appeared in the areas where the groundwater table was less than 3.0 m with a variable range of 0.51 to 1.41 m. Tamarix ramossima community appeared in the areas where the groundwater table was 3.0 to 6.0 m with a variable range of 0.85 to 1.94 m, and weed habitat appeared in the areas where the groundwater table was 3.0 m with a variable range of 1.41 to 2.46 m. The results are helpful for the allocation of surface water in Ejina eco-irrigation district.%为探讨额济纳沿河及支流密集区生态水位,运用GPS、RS和GIS技术,结合地面定位点观测,对不同植物群落与地下水位间的关系进行研究.东西两河的干流段及西河下游沿河采用单点法分析；东河下游的支流密集区采用地下水位等埋深与植物群落覆盖图叠置法分析.结果表明,河段不同地下水埋深不同,东西河干流段的沿河地下水位埋深为2.14～2.27 m,水位变幅为0.61～1.14 m；西河下游沿河地下水埋深2.52～3.88 m,变幅0.90～1.09 m;安都草原北端地下水埋深2.48～3.39 m,变幅0.26～0.33 m.东河下游支流密集区的植物群落不同,相应的地下水位埋深不同,胡杨群落的地下水埋深＜3m,水位变幅0.51～1.41 m;柽柳群落的埋深3.0～6.0 m,变幅0.85～1.94 m;杂草地的埋深＜3m,变幅1.41～2.46 m.研究成果可用于指导新建额济纳生态灌区地表水的配水管理.
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