黑河下游额济纳绿洲变化规律及其相关因素分析

Analyses of variations of the Ejina Oasis and relevant factors in the downstream of the Heihe River,Northwest China

通过处理额济纳旗地区的卫星数据，以归一化植被指数为重要指标，对可能影响绿洲的各种人为和自然因素进行了定量分析，其中包括年径流量、年降雨量、高程、坡度和地下水埋深等。结果表明：当通过狼心山的黑河流量大于3×10^8m^3／a时，额济纳绿洲面积与黑河下游径流量呈良好的线性关系；该地区植被的生长和降雨几乎无关，两者相关系数为0．016；绿洲植被生长与高程有一定关系，最适宜绿洲植物生长的高程为930-950m；坡度和植被生长也有一定关系，坡度小的地方，植被相对茂密；地下水埋深对植被的生长存在密切的关系，用植被覆盖率的概念得到最适宜绿洲植物生长的地下水位埋深为3．2～3．8m。

This paper discusses the variations of the Ejina Oasis and relevant factors in downstream Heihe River. The variation in the oasis area through the years is monitored by use of meteorological satellite images. The relationships between the oasis area and factors such as river flow rate, rainfall, altitude, slope and depth to groundwater are analyzed. The following conclusions can be drawn： （1） There is a good linear relationship between the area of Ejina Oasis and runoff of Langxinshan mountain, when the runoff is larger than 3 × 10^8 m^3/ a. （2） There is little relationship between oasis and rainfall. （3） The oasis vegetation grows well if the altitude is between 930 m and 950 m a, s. 1. in the Ejina area. （4） The oasis vegetation also grows well if the depth to groundwater is between 3.2 m and 3.8 m.