|
|
|
| Rules of Erosion & Sediment Yield and Benefits of Flood & Sediment Reduction of Soil and Water Conservation Measures in the Middle Reaches of the Yellow River |
| Zhu Jinzhao,Hu Jianzhong |
|
|
|
|
Abstract The course sands in the middle reaches of the Yellow River are mainly from the reach from Hekou to Longmen, Jinghe River, Luohe River, Weihe River, etc., and the source of course sands areas and strong erosion areas happen to be in the similar areas, that is, the so-called areas of course sands and strong erosion (ACSSE). The ACSSE covers an area of 78600km2, producing 69.2% of the total sediment and 77.2% of the total course sediment with only 22.8% of the total basin areas. The soil erosion module in sub-region one of the gully and hilly region of the Loess Plateau appears largest from 12420 to 36440t/(km2·a) contrasted with other areas. The measures of soil and water conservation including terraced fields, forestland, grassland, dam, etc., have played good functions in reducing flood and sediment. The results on study in reach from Hekou to Longmen show that the annual reduction of sediment of soil and water conservation measures is from 0.208 to 0.275 billion tons in the 80' of the 20th century, and from 0.320 to 0.448 billion tons in the 90', 0.316 billion tons from 1990 to 1996, through the hydrological method. The functions and benefits of that in Jinhe River, Luohe River, and Weihe River are all prominent. Through the roles of interception and absorption of the canopy layer, litter layer, and root and soil layer, the benefits of flood and sediment reduction of forest vegetation are prominent. Contrasted with neighboring non-forest or less-forest areas basin, the sediment reduction rates get to 78%～96% in a lot of experimental basins with the artificial forest in Western Shanxi and Eastern Gansu, etc., diminishing the strongly changing flood disasters and controlling the soil erosion radically. Further study on scaling of variation of flood and sediment in different scale basins should be strengthened henceforth.
|
|
Received: 21 May 2004
|
|
|
|
|
|
|
