Based on the distribution of hydrological stations

the study area was divided into 98sections controlled by hydrological stations and then

234 soil erosion units were determined according to the different soil erosion areas. The variation of sediment yield

sediment reduction rate

and the area variation and spatial distribution were analyzed for different degrees of sediment yield in the different soil erosion areas in different control periods.The control standards for the different soil erosion areas on the Loess Plateau in the future 20years were put forwarded:Soil loss is controlled at 3.6×108t and soil erosion modulus is less than 1300t/(km2·a). For the different soil erosion are-as

soil erosion modulus is 3000t/(km2·a) in loess Mao hilly and gully region

2000t/(km2·a) in loess Liang hilly and gully region

2000t/(km2·a) in arid loess hilly and gully region

1000t/(km2·a)in loess gentle slope hilly and gully region

1000t/(km2·a) in wind and sand loess hilly and gully region

1000t/(km2·a) in lo-ess piedmont hilly and gully region

300t/(km2·a) in forest loess hilly and gully region

1500t/(km2·a) in loess tableland hilly and gully region

3000t/(km2·a) in loess residual plateau hilly and gully region

500t/(km2·a) in loess terraces region

500t/(km2·a) in wind and sand grassland region

and 100t/(km2·a) in plateau mountain and rock region.The key control areas in the future 20years are loess Mao hillyand gully region (2.20×104km2)

arid loess hilly and gully region(1.50×104km2)

loess tableland hilly and gully region(8600km2)

and loess Liang hilly and gully region(4600km2).