Solution of hydrological survey control system of important lakes in western China

The survey of some important lakes in western China is a national water conservancy prophase project. There are a large number of lakes in the western part of China and most of the them are located in high-altitude areas. Because of their remoteness, uninhabited and inconvenient traffic conditions and harsh natural environment, no systematic scientific surveying work was conducted for the most lakes. These lakes are unclear in basic condition and blank in historical data and cannot meet the requirement of lake development and management, ecological and environmental protection, water resources management, scientific research and other work. Therefore, the State Council decided to carry out the survey work. In this paper, the solution of hydrological survey control system of five major lakes in Tibet is summarized. Due to without plane coordinate leading position in surveying area, the combined survey by using the world IGS tracking station and the lake control site was innovatively adopted to determine the plane coordinates of the accurate control points. In the light of less elevation points in the survey area, EGM2008-based gravity field model was innovatively adopted to calculate the elevation of the lake survey control site. The results have been verified, which play a decisive role in the survey of some important western lakes.