Because of the extremely continental dry climate, the Heihe River basin is characterized by less precipitation, rapid evaporation and low runoff ratio. The mountain watersheds of the Heihe River basin receive much more precipitation, and possess lower temerature and lower evaporation rate as compared with the basin area in front of the mountains, therefore are the runoff generation area of the Heihe River basin. A trend analysis indicate that, in the Heihe River basin during the 40 years from 1956 to 1996, air temperature increase is mainly in winterm, next in autumn, while summer precipitation increase trend. The runoff simulation is carried out with a model for simulating the response of monthly runoff from the mountain watersheds in ta inland area of northwest China to climate change. Taken the mountain watershed of the Heihe River basin controlled by the Yingluoxia Hydrometric station as an example, the water balance and hydrological processes are simulated. The water balance simulation indicates that from the dry years to the wet years, precipitation, evaporation, runoff and runoff decrease. The simulation of funoff change under the global warming indicates that, from 1990s to 2000s, as compared with the runoff during 1980s, along with the increase of air temperature, precipitation and glacier melt water increase in some amount. This compesates in some degree the runoff reduction caused by the increment range is within 3%. Then, to 2010s and 2040s, the increase of precipitation and glacial melt water is not enough to compensate the runoff reduction caused by air temperaturre increase, and the runoff will decrease in the aptitude within 10%.
展开▼
