Effect Of Artificial Meicago Soiva And Caragana Korshinskii Communnities On Runoff, Sediment Under Simulated Precipitation Conditiongs

Vegetation is one of the key measurements for soil and water conservation in Loess Plateau. However, there are few researches on the influence of native communities on the runoff and sediment in this region. Based on artificial precipitation and laboratorial analysis, the changes of Runoff-sediment-yield characteristics were studied on slopes with two native communities (Meicago Soiva and Caragana korshinskii), and these conclusions could be drawn as follows:(1)Effect on Runoff: Compared with control slope, the time from precipitation to runoff emergence was delayed on the slopes with Meicago Soiva and Caragana korshinskii. With the increasing of rain intensity and invariability of the vegetation coverage, the time from precipitation to runoff emergence become shorter. In addition, with the increasing of vegetation coverage and the invariability of the rain intensity, the time from precipitation to runoff emergence become longer. The time in control slope is 3min when the rain intensity is 1.28mm/min while the time is 55s when the rain intensity is 2.47mm/min.With the increase of rain intensity and invariability of the vegetation coverage, the runoff yield is increasing sharply. On the other hand, the runoff yield is decreasing with the increase of vegetation coverage and the invariability of the rain intensity. The runoff yield on slope with Caragana korshinskii communities is greater than on the slope with Meicago Soiva community.(2)Effect on sediment: The sediment yield on slope is decreasing with the increase of vegetation coverage. In the beginning stage, the sediment yield increased slowly with process of precipitation. In the latter stage, however, it increased sharply with precipitation process. The increasing of sediment yield has significant difference among slopes with different vegetation coverages. The reduced sediment yield could reach 70-80% when vegetation coverage is above 80%. Compared with Meicago Soiva community, the Caragana korshinskii communities has better capacity in reducing sediment.(3)Infiltration characterstics: The two native communites can improve the capacity of soil infiltration. The cumulated infiltration yield, instantaneous infiltration yield and instantaneous infiltration vococity are all increasing with vegetation coverage. The early infiltration ration and stable infiltration ratio could reach 1.18 mm/min and 0.60mm/min respectively when the rainfall indensity is 1.28mm/min and vegetation coverage is 80%.â‘¡The infiltration ratio and rainfall indensity have significant linea relationship.â‘¢The infiltration ratio and rainfall time have significant relationship of power function.â‘£Compared with ck,the vegetation can strongen the soil infiltration,and the Caragana korshinskii community is stronger than Meicago Soiva community in the same coverage.(4) In order to improve work efficiency and accuracy, a new device, runoff and sediment automatic monitoring system (RSAMS), were use in this study. Based on the comprison between artificial measurement results and RSAMS results, some advices were suggested in this paper.