By considering the three objectives of ecology

economy

and society in soil and water conservation

the two principles of guaranteeing regional grain self2sufficiency and increasing vegetation coverage

as well as the current status of soil and water loss in the Chaohe River basin in 2005

the three allocation plans of food grain security plan

eco2priority plan

and comprehensive plan are established

as soil and water conservation measures.Impacts of the three allocation plans for soil and water conservation on annual runoff of the Chaohe River are simulated and analyzed based on the water reduction norm of level terraces and forest-lands under different precipitation schedules.Results show that if all the soil erosion areas are converted to artificial woodland

the impact to annual runoff reduction is greater

with the reductions in wet year

normal year

and dry year being 8.27 %

8.28 %

and 11.13 % of the annual average runoff

respectively.Adopting comprehensive allocation plan may affect annual runoff greatly and the reductions in wet year

normal year

and dry year are 11.42 %

8.38 %

and 13.21 % of the annual average runoff

respectively.The impact of grain security allocation plan on annual runoff reduction is littler and the reductions are 7.59 %

6.03 %

and 9.11 % of the mean annual runoff during wet year

normal year

and dry year

respectively.