近50a来黑河流域水文及生态环境的变化

CHANGES OF HYDROLOGY AND ECOLOGICAL ENVIRON MENT DURING LATE 50 YEARS IN HEIHE RIVER BASIN

利用详实资料，对比分析了４０年代以来不同时期黑河流域水文及生态环境的变化特征，并对不同时期流域水土资源开发利用规模及出山径流的变化进行对比分析，结果说明：本世纪４０年代以来，流域中游地区地表水利用量增加了１９倍，灌溉绿洲扩大了８９．５％，使流域３３条支流相继断流，干流下游水量减少了５１％，终端湖泊干涸，水质恶化，土地盐碱化和沙漠化在全流域发展，沙漠化土地面积自１９４９年以来增加了４％～１１％。人类对流域水土资源的大规模开发利用是产生这些变化的主要因素。

The purpose of study is to investigate the influences of water resource development on the ecological environment in the arid regions of northwest China with Heihe River basin as an example. During late 50 years, the Heihe River system changed heavily: the discharge of the lower reaches of the river decreased seriously; more than 30 tributaries and its terminal lakes have dried up. Such hydrological change results in the degradation of the ecological environment, secondary salinization and land desertification in whole basin. Since 1949 the water consumption in the middle reaches area of the basin has increased by 19 times; the area of oasis has added by 89 5%; thus, the discharge in the lower reaches of the river has reduced by 51%; the spring water output has reduced by 22 8%; mineralization degree of surface water and shallow groundwater in the middle and low reaches have been increasing due to variations of hydrological condition and redistribution of water resources. Furthermore, both surface water and groundwater were seriously polluted. In the middle section of the river basin some 43 18×10 4 hm 2 of grassland degraded seriously; 0 93×10 4 hm 2 of forest have been destroyed and the desertified land has increased to 5 35×10 4 hm 2. In the lower reaches of the river basin, degraded vegetation has reached 27 18×10 4 hm 2 and land desertification is expanding at a rate of (1 1￣1 3)×10 4 hm 2 per year. Human activities are the main reason responsible for these changes.