Impact of Water Diversion of Ningxia-Inner Mongolia Irrigation Area on the Mainstream Streamflow of the Yellow River

The irrigation area taking water from river will certainly have influence on the runoff. Comparing the relations between the runoff of lower cross section and the major effect factor before and after water diversion, we can quantitatively analyze the influence on the runoff change. This article uses some methods, such as the reach cross section amount of runoff month relations, the diversion graduation amount of runoff relations, the multiple regression analysis method and the cross section amount of runoff interpolation, to analyze the water diversion of Ningxia - Inner Mongolia irrigation area from 1997 to 2006. We conclude that the influence caused by the water diversion from the Yellow River Ningxia - Inner Mongolia reach main current runoff. The results show that, in the recent ten years, as Ningxia - Inner Mongolia irrigation area diverts 0.1 billion m(3) water, the amount of runoff of Toudaoguai cross section will reduce by 0.066 billion m(3), and as diverts net 0.1 billion m(3) water, correspondingly 0.098 billion m(3) runoff will be reduced. The findings indicate that, the influence of Ningxia - Inner Mongolia irrigation area is mainly decided by the net amount of water diverted in the irrigation area. The decrement of Yellow River main current runoff caused by the irrigation area diversion is related to draws back directs of the irrigation area.