ENVIRONMENTAL EFFECT OF ENGINEERING ACTIVITIES OF YELLOW RIVER WATER CONSERVANCY IN ANCIENT CHINA

Historically in China, the engineering activities of the Yellow River water conservancy were mostly focused on the water harnessing, while the silt harnessing was neglected.As a result, the Yellow River became gradually a world-famous above-ground suspended river and a "watershed" in the middle part of the Huang-Huai-Hai (Yellow R.-Huaihe R.-Haihe River)Plain.This has, on the one hand, changed the primary geological environment of the largest plain of China and, on the other hand, created the new geological environment of the Bohai Sea, Yellow River delta and coastal plain with an area over 10 000 km² in the recent 800 odd years.
Based on the historical facts, it is suggested in this paper that the traditional concept on the Yellow River water conservancy should be changed and the silt in the Yellow River should be paid attention to.The silt is regarded as a precious wealth and should be, in an aimed and planned way rather than a laissez-faire attitude, led to an appropriate area to fill the sea and create the land.As the soil loss in loess plateau is an irresistible natural process and the amount of silt is practically infinite, the sea-filling and land-creation by utilizing the transported silt by Yellow River (though in a relatively long period of time)is incomparably more advantageous than by mountain excavation and sea-filling.
The paper suggests that the ideal area for the land accretion with the Yellow River silt is the Yellow Sea coast at northern Jiangsu rather than the Bohai Sea, because the latter is small in area and is our inland sea.The Bohai Sea could be quickly filled up with the silt of Yellow River, but the changing of Bohai Sea into land is quite harmful to North and Northeast China with respect to climate, hydrology etc.Key words:Yellow River;water harnessing;silt harnessing; sea-filling and land accretion