黄河源区生态环境恶化的现状及其原因

黄河是中华民族的母亲河 ,黄河流域是世界上著名的四大文明古国的发祥地之一。远古时代黄河流域气候湿润、水源丰富、土地肥沃。轩猿黄帝和他的沿黄部落就在这里开始创造中华文明。而今黄河下游常年发生断流 ,中游水土流失严重 ,河源区生态环境恶化 ,已引起我国政府和民众的关注。目前 ,防治黄河源区生态环境进一步恶化的研究工作必须加大力度 ,在财力、人力方面应给予更大的支持 ,及早编制该区治理生态环境的规划 ,加强环境保护措施

The Deterioration of Ecology Environment and Its Cause in the Lake Regions of the Yellow River Source, Qinghai, China

The Yellow River is the mother river of the Chinese nation, andthe watersheds of the Yellow River is also one of four famous countries with an ancient civilization in the World. In remote antiquity, the climate was warm and moist, abundant water resources and good soil favorite to the Xuanyuan Emporia and his tribe lived along both sides of the Yellow River, and created a Chinese civilization. But at present a broken flow of the Yellow River is frequent in the lower reach and heavy soil erosion in the middle reach, ecological environment steadily deteriorated in the headwater. Attention has be paid to these situations by the chinese Government and their people.Over the confluence of the Maqu River and Heihe River (the range before the Huashixia)is called the source region of the Yellow River with an area of 22000km2, the length of the riverbed 323km from the Maqu River to the headwater with slope of 1.2%o. The whole source region is a Cenozoic tectonic depression situated between Buqingshan and Bar Yanhara Mountains, and can be divided into five landform units based on geomorphologic features, and show as follow from north to south: 1.Zagarishan-Buqingshan high-middle mountainous region 2.Joguzhongle Basin-Xinsuhai Lake-Gyaring Lake-Ngoring Lake-Maqu River broad-valley basin region 3.Joguzhongle Mountain-Mianshaling Ridge lower mountain-hill region 4.Kariqu River-Heihe River broad-valley basin region 5.Baryan Har high-mountainous region The watershed region of the Yellow River is a great Tertiary lacustrine basin with red-clastics and redmudstone stratigraphies distributed extendedly in both south and north sides of present lake basin. During the early Pleistocene, the northern side of the paleolake extended to the southern piedmont of the Buqingshan Mountain about 30km farward to the Ngoring Lake. Beginning in the middle Pleistocene, the Buqingshan and the Baryan Har Mountains were strongly uplifted, and the high-mountainous zone upwards into the cryospherice in about 700 ka BP and developed three larger icecaps on the Buqingshan Mountain, Zagari Mountain and Baryan Har Mountain, respectively, and glacial meltwater flows into basins and depressions, a large glacial-water lake appeared first. In the Last Interglacial stage (30-40 ka BP) the lake water flowed and erosed along the fault broken zone, cut down a river-valley and link to the Yellow River, and uniform big lake separate into many small lakes. Up the maximum stage of the Last Glaciation (about 20 ka BP) thick-sandy loess layer and actives desert dune were formed in the Mianshaling Hill, Xinxinhai Lake and so more because of drycold climate, lake level dropping, strongly wind activity and lake beach extending at that time. The Madoi River was formed in the Holocene Megathemal at about 6 ka BP. As global climatie warms, the mean annual air temperature of the watershed region became warmer, and mean annual air temperature increasing rate is 0.08C/10a at Madoi County, low limit of permafrost have shift up 58m at Madoi Town. In range of Madoi County there were 4077 lakes in past, but now 2000 or more small lakes have dried up, and others are contracted and salinized. The degration of eco-environemnt in the source region has became very serious, the degraded grasslands reached to 24143300 Mu, which is 70% of total grassland area, 63.7% of total area at 1999 in Madoi County. The land desertification is expanding rapidly, and the expanding rate rose from 3.9% in 1970s to 20% in 1990s. The Gyaring Lake (526km2 in area) and the Ngoring Lake (610.7km2 in area) are the two largest lakes in the region. And lake level of the Ngoring Lake has dropped 5m in past 20 years more, and outflow discharge of the lake is 7.8m3/s in 1993 and only 2.71m3/s in 1999, and the outflow discharge of the Gyaring Lake into the Ngoring Lake is onkly 0.006m3/s, resulting in an evidently lake level dropping in the Ngoring Lake in 1999, which reached up 1cm dropping per 4～5 days. The biodiversity is decreased, too. The region is fragile area of ecological environment because of the vast cryospheric conditions. After degeneration of grassland ecological environment, the reclamation of ecological condition will become more difficult. Thus, improvement and protection of ecological environment are important tasks for keeping an ecological environment system balance, and have significance for sustainable development in the region.