Satellite Snow-Cover Monitoring in the Qilian Mountains and an Analysis for Characteristics of Stream Snow-Melt Run-Off in the Hexi Region, Gansu, China

The images of NOAA/TIROS-N APT, AVHRR and a few Landsat MSS obtained from 1980 to 1985 are analysed in this paper. It is found that the snow-cover distribution in Qilian Mountains is above 3700 m a.s.l. during winter to spring every year. There are two concentrations of snow cover. One is on Mount Leng Longling in the upper reaches of the Shiyang River and the other is located between Hala Lake and Mount Danghe Nanshan.Based on preliminary investigations, it is known that the surface water resource in the Hexi region is 68 8 × 108m3, of which about 24.8% is from glaciers and melting, and the snow-melt run-off is 7.63 × 108m3, equal to 62.6% of the total amount of spring run-off.The average value of Cv for spring run-off in the Shiyang River, Heihe River, and Shule River is 0 32 and the Cv value of snow-melt run-off in spring is 0.41, about three times as much as that of the annual run-off in the Hexi, region. A prediction model of spring snow-melt run-off at the Ying Louxia Hydrometric station in the Heihe River area can be constructed by using hydrometeorological data and snow-cover percentage for the Heihe River basin obtained from NOAA/TIROS-N APT, and AVHRR images. The prediction models (2) and (3) have been tested by the Water Resources Management Office of the Heihe River basin in the Zhangye and Flood Prevention Office of Gansu Province. The prediction accuracy is suitable for demands.