The research area at the watershed scale has been selected as the typical inland river basin - the Heihe River Basin, with an area of approximately 128700 km2. It is the second largest inland river basin in China, located at longitude 96 ° 42 ′ -102 ° 00 ′ E and latitude 37 ° 41 ′ -42 ° 42 ′ N. It includes different landscape types such as alpine ice and snow belts, forest grassland belts, plain oasis belts, and Gobi desert belts. The Heihe River Basin is a research base for inland river basins in China, with a good research foundation, a complete observation system, and rich data accumulation. Taking into account the main hydrological processes of the inland river basin, including cold region hydrology, forest hydrology, ecological hydrology, and arid region hydrology, three representative key experimental areas were selected throughout the entire basin to conduct comprehensive observation experiments Upstream cold region hydrological experimental area. It is selected as Babaohe sub basin of the east branch of the upper reaches of the Heihe River, where the snow cover is stable in winter and the frozen soil is developed, which is suitable for the study of Hydrology in cold regions. There are Qilian Hydrological Station and Qilian Meteorological Station in the experimental area, with a catchment area of approximately 2452 km2 above the hydrological station Forest hydrological experimental area. Including a series of mountain front sub basins such as Dayokou and Haichao Dam, the landscape types include glaciers, snow cover, permafrost, alpine grasslands, and forests. The main observation object of this experimental area is forest hydrological processes Hydrological experimental area in the middle arid region. This area mainly includes Zhang, Lin, and Gao oases. In this experimental area, two hydrological stations, Yingluo Gorge and Zhengyi Gorge, on the main stream of the Heihe River, are used as control points for surface water input and output, forming a complete water cycle system. Taking into account the representativeness, integrity of the watershed or irrigation area, research foundation, possibility of aerial remote sensing experiments, and traffic accessibility, an encrypted observation area is selected.