Characteristics And Control Measurements Of Hillslope Soil And Water Loss In Ili Valley

Ili vallley of western TianShan mountians in Xinjiang has special geographical location,and belongs to the humid continental temperate climate.The degree of water erosion is moderately strong in Ili Valley.Increasingly serious soil and water loss causes soil degradation,reduces siol water content and soil fertility,causes heavily soil erosion,and threatens to development of sustainable agricultural and soil security directly.Therefore,it is urgent to explore the characteristics of soil and water loss and preferable sediment and runoff reduction of control measurements.Firstly,this study analyzed correlation among terrain,vegetation and soil.The second,characteristics of hillslope soil and water loss was researched under 20、10 and 36mm/h rainfall intensities in the field by artificial rainfall simulation,and compared the effects of sediment and runoff reduction on five control measurements(bare land,Ceratocarpus arenarius L.,Kochia prostrate(L.)Schrad.,fish scale pit and horizontal ditch)under artificial rainfall simulation condition.To provide sustainable utilization of land resources and effective measurement of soil and water conservation,had the following primary results:(1)Slope positions and vegetation influenced distribution of organic matter content.Vegetation coverage,content of organic matter and clay had strong relationship on the slope posions.The results of correlation analysis showed significantly positive correlation among soil erodibility factor K,vegetation coverage,organic matter content,soil bulk density,sand and clay.(2)Initial runoff time was largely affected by 3 rainfall intensities,initial runoff time of slope positions discreased when rainfall intensities increased,and followed the order lower>middle>upper.Initial runoff time of bare land was so short that suffered rainfall erosion easily,while runoff of horizontal ditch plot was never happened under 3 rainfall intensities.(3)Runoff rate and sediment concentration of slope positions and control measurements were impacted by rainfall intensities.Runoff rate and sediment concentration increased significantly in a short time under rainstorm.Runoff rate followed the order upper>middle>lower,sediment concentration followed the order upper>middle>lower under 3 rainfall intensities.The soil erodibility factor K gradually reduced from upper to lower.It is fitting relation of sediment concentration and runoff rate that upper had polynomial function relationship,middle and lower had linear function relation.And sediment concentration had small sensitivity when runoff rate increased in lower.(4)Sediment concentration and runoff rate had linear function relation on bare land,Ceratocarpus arenarius L.,Kochia prostrate(L.)Schrad.and fish scale pit.Sediment and runoff reduction of all measurements listed in the following order: horizontal ditch>Kochia prostrate(L.)Schrad.>fish scale pit>Ceratocarpus arenarius L.>bare land.Therefore,fish scale pit and Kochia prostrate(L.)Schrad.Showed more obvious effects on sediment and runoff reduction than the other control measurements.