Sediment delivery ratio(SDR) is the important indicator to represent the basin soil erosion and sediment:one of the sediment transport characteristics.Based on the measured data of runoff plots

small watersheds and hydrological stations of loess hill gully region

using the methods of runoff plots measured data and unit watershed erosion modulus

the SDR of 4 spatial scales were analyaed.The results showed that:(1)The SDR of watersheds between area of 10 and 100 km2 was approximated by two methods estimated.It was feasible to use unit watershed materials to calculate SDR

while there was no runoff plots data.(2)For the hydrological station controlled watershed

it could take the watersheds between 1 and 100 kmz as the unit watershed to calculate SDR while there was no material of watershed below 1km2.However

it has too large error for tributary of different erosion types.(3)Watershed management measures have obvious effect for reducing SDR

but its effect has a degree of lags.