河西走廊水资源特征及其循环转化规律

Characteristics and Cycle Conversion of Water Resources in the Hexi Corridor

河西走廊水资源主要以雪冰水资源、地表水资源与地下水资源的形式存在,分布于石羊河、黑河、疏勒河3大相对独立的流域水系。南部祁连山区发育大小河流共计57条,多年平均出山径流量71.29×108m3,总体而言,近50 a出山径流变化比较稳定。走廊平原主要由8个大型的构造地貌盆地组成,盆地地下水主要接受出山河水及引灌河水的入渗补给,是地表水资源的重复表现形式,多年平均地下水补给量为42.42×108m3。近50 a来,地下水补给量减少了17.19×108m3,由此引起泉水资源23 a来衰减了24.6%。受构造地貌的制约,自南部山区至北部盆地,地下水与河水之间经过5个不同地带有规律的、大数量的、重复的转化过程,形成完整统一的“山区地下水—地表水—南盆地地下水—地表水(泉水)—北盆地地下水”水资源循环系统。

Located in the hinterland of northwest China, the Hexi Corridor is one of the famous arid and water-shortage areas in China. Water resources exists mainly in forms of snow-glacier resources, surface water resources and groundwater resources which are distributed in three main independent river basins, i. e. , the Shiyang River Basin, Heihe River Basin and Shule River Basin. The south Qilian Mountains （upstream） with high elevation is the headwaters of the rivers. The plain in the Hexi Corridor, located in the north （middle and lower reaches）, is the main irrigated area in the Hexi Corridor. As many as 2 444 glaciers with a total area of 1 657.21 km^2 are distributed in the alpine zone of the Qilian Mountains, and the volume of water resources of the glaciers is 8.0131× 10^10m^3. Fifty-seven streams in various sized rise in the south Qilian Mountains, their total annual runoff volume out of the debouchures is 7.1291×10^9 m^3, the change process of runoff in the mountainous region is relatively stable in recent 50 years. The annual runoff volume of the Shiyang River in the east Qilian Mountains is in a decrease trend, that of the Heihe River is relatively stable, and that of Shule River is in an increase trend. The plain in the Hexi Corridor is mainly composed of 8 large tectonic basins, where groundwater is mainly recharged by the rivers and the infiltration of irrigation canals. The average annual groundwater recharge is about 4. 2419×10^9 m^3 in recent 50 years; however, the groundwater recharge in the region has been decreased by 1.7189×10^9 m^3, which results in a reduction of spring water resources in recent 23 years. In the plain of the Hexi Corridor, the total water resources composed of surface runoff out of the debouchures and groundwater is 7.6721×10^9 m^3, and the proportions of surface runoff out of the debouchures and groundwater account for 92.9% and 7.1% respectively. Affected by the conditions of tectonic landforms in the region, there are the regular, massive, repetitious conversion processes between groundwater and rivers, and a complete water resources cycle system of ＂groundwater in mountainous region-surface water-groundwater in southern basin-spring water-groundwater in northern basin＂ is formed.