黄河源区水环境变化及黄河出现冬季断流的原因

自1954年有水文观测资料以来，黄河曾在青海省玛多县黄河沿水文站发生过3次断流。本文在分析黄河源区水环境特征及其影响因素的基础上指出，鄂陵湖、扎陵湖的环湖融区调节能力低，当遇到连续干旱、冬季其调节水量不足以维系黄河径流时便会发生断流，这是断流的主因。湖水位降低、开采沙金、过度放牧等自然和人为因素也会对黄河发生断流产生影响。鄂陵湖口附近黄河上修建的水电站开始蓄水，提高了两湖及环湖融区的调节能力，今后黄河冬季出现断流的可能性将大为降低。

Changes of the water environment in the headwater area of the Yellow River and the cause for the zero-flow of the river occurring in winter

Hydrologic observations of the Yellow River began in1954.Since then zero-flow of the river has occurred three times at the Huangheyan Hydrologic Station in Madoi County.Since1999the zero-flow of the Yellow River has become an issue of extensive concern by the society.On the basis of an analysis of the hydrologic environment of the headwater area of the Yellow River and its influence factors,the authors indicate that due to the low regulation capacities of the thawing areas around the Ngoring Lake and Gyaring Lake,their regulated flow is insufficient to maintain the runoff of the Yellow River during winter or continuous drought seasons and thus the zero-flow occurs.In addition,natural and an-thropogenic factors such as the lowering of the water level of the lake,mining of placer gold and over-grazing also have important influence on the occurrence of the zero-flow of the Yellow River.As the hydraulic power plant built on the river near the outlet of the Ngoring Lake has begun to impound wa-ter,the regulating capabilities of the two lakes and their surrounding areas have increased.Thus the possi-bility of the occurrence of the zero-flow of the river will be reduced considerably in the future.