Study On Water Resource And Ecological Environment In The Lower Reaches Of Heihe River Basin Based On Remote Sensing

In the recent about 20 years, the ecological environment of Heihe River Basin has been deteriorating obviously due to natural and human reasons. In this dissertation, by adopting numerical simulation combined with remote sensing technology, the problem of water resources and ecology environment in Heihe River Basin, especially in downstream of Heihe, are analyzed in detail.The hydrogeological conditions of Heihe River Basin are obtained through field investigation and data collection. And the groundwater depth is estimated by groundwater modeling technology.The changes of area covered by vegetation with time on the regional scale are monitored by use of multi-source satellite data. A new method, which is called Equal Area Method, is given to calculate the area of oasis in different years, and is applied to Ejina oasis in downstream of Heihe River. It is shown that the area of this oasis has decreased at the rate of 9.5 km~2/a in recent 14 years.The relationship between the oasis area and factors such as river flow rate, rainfall, altitude, slope and depth to groundwater are analyzed. The vegetation coverage rate is proposed to describe the relationship between the groundwater depth and the vegetation state and 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 lager than 3×10~8m~3/a. (2) There is little relationship between oasis and rainfall. (3) The oasis vegetation grows well if the altitude is between 930m and 950m a. s. 1. in the Ejina area. (4) The oasis vegetation also grows well if the depth to wroundwater is between 3.2 m and 3.8 m.