Impact of vegetation restoration on hydrological processes in the middle reaches of the Yellow River, China

摘要: Sediment discharge from the Yellow River originates mainly drainage area between Hekouzhen and Longmen, i.e., Helong area. Spatial-temporal variations of vegetation cover in this during 1981–2007 period have been investigated using GIMMS SPOT VGT NDVI data. We also analyzed interannual changes annual runoff sediment discharge, consequences precipitation change Grain for Green Project (GGP). The results show that has increased period. northwestern part area, where flat sandy lands are covered by grass, experienced largest increase. region declined is largely found southern southeastern which a gullied hilly or forested. Although was relatively low 1999–2007 period, showed significant increase due to implementation GGP. During most improvement occurred areas Loess Plateau, such as basins Kuyehe Tuweihe rivers middle lower reaches Wudinghe Yanhe rivers. A comparison average maximum earlier (1998–2002) stage next five years (2003–2007) GGP indicates with increases 10% 20% account 72.5% 36.4% total respectively. Interannual variation shows declining trend, especially since 1980s, when decrease became very obvious. Compared 1950–1969 1980–2007 reduced 34.8×108 m3 6.4×108 t, accounting 49.4% 64.9% There positive correlation discharge. This reversed 1999 increased, associated Less an important factor driving 1999–2007. However, restoration may played role accelerating enhancing evapotranspiration alleviating soil erosion.