新疆阿克苏地区近40 a气候、水文变化特征分析

Analysis on the Change Characteristics of Climate and Hydrological Conditions in Aksu Prefecture, Xinjiang since Recent 40 Years

近20 a来,阿克苏平原绿洲区气候明显变暖增湿,戈壁区略有变干的迹象。同期,由于气温升高,冰川消融加快,山区降水增多,源流出山口径流量略有增加;根据塔里木河干流阿拉尔水文站监测结果,近40 a来,年径流量呈持续稳定减少趋势。20世纪90年代,径流量平均距平为-4.85,径流量减少达10.58%。这主要是人类干预和源流区粗放农业发展,耗水量不断增加,导致汇入塔里木河干流水量不断减少,从而引起中下游生态急剧恶化。

The study area, Aksu Prefecture, is located in the southern piedmont of the Tianshan Mountains and the northern marginal zone of the Tarim Basin, its total area is 1. 325 × 10^5 km^2, and the population is 2.2 × 10^6. In this paper, the change of climatic and hydrological conditions in the study area is researched. The results are as follows： （1） Under global warming and the trend that the climate is changing from warmingdrying type towards warming-wetting type in northwest China, the climate change in Aksu Prefecture is different to some extent. Air temperature has been mainly increased since recent 20 years, the precipitation increase, however, occurred mainly during the period from the 1960s to the 1980s, the annual precipitation was increased in the ecotones and the plain oases but decreased in the Gobi deserts, and the difference between the annual precipitation and evaporation becomes high. All these promote the occurrence of dust storms in the prefecture. （2） The air temperature and precipitation change in a gradient way with the increase of elevation, the increase rates of air temperature and precipitation are reduced with the increase of elevation; the response of air temperature to the events of severe invasion of cold air current is lagged due to the effects of mountainous glaciers. （3） The change of the area of modern glaciers is not so obvious in recent 40 years; under the effects of climate change in northwest China, the annual runoff volumes of the 5 source streams at their debouchures has been increased by 9.25% in average since recent 20 years, and their increase is stable; however, the annual runoff volume of the mainstream of the Tarim River has been continuously reduced since recent 40 years, thus, the ecological environment in the lower reaches of the Tarim River is seriously degenerated. （4） Human activities are the dominant factor affecting the change of water resources in Aksu Prefecture. The excessive exploitation and utilization of water resources in the source stream watersheds have resulted in the enlargement of lands discarded from cultivation, reduction of the areas of steppes and waters, enlargement of the area of vegetation-uncovered lands, and more serious degeneration of ecological environment.