Annualized Agricultural Non Point Source model(AnnA GN PS)

a continuo us simulation model at water shed scale

simulates surface water

sediment

nut rients

and pesticides leaving the cells and their transport through watershed.The Daning River water shed is selected as a study case.The characteristics of sediment delivery are studied based on landuse

soil

topographic data

and eight year climatic data from 11 meteorological stations.Averaged annual sediment load is 1.25×106t/a at the Wuxing station

rapidly rises up to 1.81×106t/a at the Dachang station

and reaches 1.95×106t/a at the water shed outlet.Xixi River

one of the biggest tributaries in the Daning River watershed

has the largest volume of water discharge up to 20.97%of the total at the watershed outlet.Dongxi River

the second tributary

has the most sediment load up to 26.88%of the total at the watershed outlet.In addition

the area of left bank in the middle watershed(from Wuxi station to Dachang station)is another large sediment source.The sediment delivery ratio(SDR)of the whole watershed is 0.30 in accordance with published references.Viewed from four main stream stations

i.e.Do ngxi river outlet

Wuxi station

Dachang station

and the watershed outlet

the SDR is positively correlated with the watershed area.However

the relation is not significant in the six tributaries owing to the high variatio ns of drainage area

slope

runoff rainfall facto rs

land use/ land cover

etc.