Runoff Analysis and Estimation of the Binggou Basin in the Qilian Mountain
Yang Zhihuai, Yang Zhenniang Wang Qiang (Lanzhou Institute of Glaciology and Geocryology, Academia Sinica)
The runoff forming principle and its estimation in cold region is one of the major contents on hydrology of cold region. This paper deals with, taking Binggou Basin of the Qilian Mountain as the object of study, the characteristic and regularity of the runoff forming under the condition of the cold regions, especially the effects of the variations of frozen soil upon the runoff forming. The result shows that frozen soil changes with season is one of the main factors affecting runoff forming. In the Binggou Basin, the thawed depth of frozen soil is shallow in spring. The proportions of surface runoff and subsurface that supply stream runoff during this time are about 0.45 and 0.55 respectively. As a result of thawed depth increasing after spring, 0.08, 0.65 and 0.28 of the stream runoff are supplied by surface, subsurface and groundwater runoff separately. In addition, when simulating the daily discharge of the subsurface and groundwater runoff with a linear reservoir model the storage constant K is variable with season. The K for subsurface runoff is equal to 8 in spring and then rises to 11 after spring. In contrast, the K for groundwater runoff is 60 and the variation is smaller in summer and autumn.