Sedimentary Causes and Management of Two Principal Environmental Problems in the Lower Yellow River

Flood and water shortage are two of the leading environmental problems around the world, and among the causes of the problems is sedimentation. The Yellow River brought disastrous floods in its lower reaches in Chinese history. Today, although floods caused by the river are still a formidable hazard hanging over China, it cannot provide the lower reaches with enough usable water. The ineradicable flood hazard and newly emerged water shortage problems of the river are proved to be closely associated with its immense sediment load. The over loaded flow of the river can quickly fill the reservoirs and unceasingly raise the riverbed, attenuating the capacity of reservoirs to suppress floods and provide more water for dry seasons and of river channels to convey floods. Also, the high sediment content pollutes the water and reduces the volume of usable water. In virtue of the intimate linkage between these problems and the formidable sediment load in the river, the solution to these problems should be based on sedimentation management. After reviewing the defects and merits of management measures implemented and proposed, a management scenario composed of multiple measures are recommended. Beside of persistent soil conservation to reduce the huge sediment load, more reservoirs to check sediment and regulate river flows, approaches to alleviating riverbed accretion, interbasin water transfer to mitigate water deficiency, and so on, an emphasis should be laid on use of muddy flows in order to scatter the sediment in a vast area, which was a natural process but has been interrupted by construction of embankments.