中国西北干旱区水资源利用及其生态环境问题

THE UTILIZATION OF WATER RESOURCE AND ITS INFLUENCE ON ECO ENVIRONMENT IN THE NORTHWEST ARID AREA OF CHINA

近５０年来，西北干旱区随水土资源开发利用规模的不断扩展，使区域内工农业与经济得以稳定持续发展。但同时，引起一系列生态环境变化。①大多数河流下游水量锐减，甚至断流，河道缩短，终端湖泊萎缩或干涸，水质咸化和污染趋势加剧；②土壤沙漠化和盐碱化，沙漠化土地面积达６７４９３×１０４ｈｍ２，盐碱化耕地面积逾１３５５６×１０４ｈｍ２；③植被退化，生物多样性减少，与５０年代初相比，天然森林面积减少４９％～５８％，草地面积减少１６％～９２％；④沙尘暴灾害发生频数增加，灾害程度加剧。

The northwest arid area of China,having about 1/4 of the total area o f China,is located near the center of the Eurasian continent.There are many mounta ins with elevations of 4300-7000m,which scatter between plains feeding 676 inla nd rivers.In the late 50 years,the exploitation and utilization of water resourc es in those rivers have led to the formation of 390 07×104 ha of man made oas es that scattered all over the river basins,and built of about 622 reservoirs wi th a storage capacity of 65 5×108m3 The large scale utilization of water reso urces has not only facilitated the steady development of agricultural economy bu t also resulted in very serious impacts on eco environment in the arid area: (a) The runoff courses of most rivers were shorten ed and the terminal lakes were reduced or dried up.The water quality in the lower reach esbecame worsened.(b)Soil salinization and desertification became more and more s erious in these regions.The salinized area totalled about 210 18×104ha,and des ertified area about 674 93×104ha.(c)Vegetation has been seriously degraded or destroyed.The natural vegetated area was reduced by 49%-58%,grassland reduced by 16%-92% and degraded grassland area occupied about 52%.