Aeolian activities

precipitation and human activities are the main factors affecting the delivery of the coarse sediments(0.05 mm) from the transition zones of arid and humid areas into the Yellow River in Northern China.The variations of coarse sediment transportation are determined by the total sediment yield and the percentage of coarse sediment.Based field collected suspended sediment yield

grain size of suspended sediment

precipitation

events of sand-dust storms and areas of soil and water conservation measures

the relationship between coarse sediment yield and its influencing factors were investigated in the basin of Wudinghe River.Both total sediment yield and proportion of coarse sediment in the total yield were used to describe the dynamics of coarse sediment transportation.Effects of physical process

referred to as the interactive fluvial-aeolian process

and human activities on the generation of the coarse sediment were studied

and the relationships between the two parameters and the influencing factors were investigated using geographic information system(ArcGIS) and statistical software(SPSS 12.0).The contribution of fluvial-aeolian changes and human activities to coarse sediment ratio and the total suspended sediment yield was analyzed using multivariate regression.The results showed that total suspended sediment yield correlated closely with the amount of precipitation and the area of soil and water conservation measures.The coarse sediment ratio was linked closely with aeolian factors and the area of soil and water conservation measures.It was also found that the contribution of precipitation to total suspended sediment yield was almost equal to that of human activities

while the contribution of human activities to the reduction of coarse sediment ratio was higher than that of aeolian activities.