| Xinjiang is one of the western provinces with the most serious soil erosion in China.Rainfall runoff is the main driving factor of soil erosion.Vegetation and soil types had a profound effect on the runoff and sediment yield.In this paper,the combination of natural and artificial rainfall simulation.The natural grassland vegetation,soil in Yili River Valley and 2 types of soil of Manasi County were studied as the research objects.Runoff and sediment reduction effects of different vegetation types in Yili River Valley were explored.To study the regularity of the runoff and sediment yield and its influencing factors.The erosion characteristics of 3 types of soils were compared under the same rainfall condition.By selecting sample plots,vegetation investigation,field sampling,determination of indoor sample,data processing,the following conclusions were obtained:(1)Simulated rainfall test of runoff area near Water Conservancy Bureau of the town in Yining Bayan Dai showed that:The length of initial runoff time of several types of grassland are:Pod quinoa>Yili Artemisia=Bermuda grass>Bare land;the size of the runoff rate is in the order:Bare land>Yili Artemisia>Bermuda grass>Pod quinoa;the size of the sediment concentration is in the order:Bare land>Yili Artemisia>Bermuda grass>Pod quinoa.The values of sediment reduction factor of Pod quinoa are between 0.02 and 0.11,the values of sediment reduction factor of Bermuda grass are between 0.21 and 0.58,the values of sediment reduction factor of Yili Artemisia are between 0.14 and 0.87.The values of flow reduction factor of Bermuda grass are between 0.16 and 0.76,the values of flow reduction factor of Pod quinoa are between 0 and 0.42,the values of flow reduction factor of Yili Artemisia are between 0.42 and0.88.(2)Natural rainfall experiment of runoff area near the northern slope of Yining showed that:Different vegetation types,there were differences in runoff and sediment yield in each plot.the size of runoff was in the order:Bare land>Dried apricot>Grassland>Ulmus pumila cv.jinye>Mountain peach and desert date.The effect of reducing runoff was in the order:Mountain peach and desert date(The values of flow reduction factor were between 0.37 and 0.46)>Ulmus pumila cv.jinye(The values of flow reduction factor were between 0.45 and 0.66)>Grassland(The values of flow reduction factor were between 0.51 and 0.71)>Dried apricot(The values of flow reduction factor were between 0.27 and 0.87).The effect of reducing sediment was in the order:Mountain peach and desert date(The values of sediment reduction factor were between 0.14 and 0.57)>Ulmus pumila cv.jinye(The values of sediment reduction factor were between0.38 and 0.56)>Grassland(The values of sediment reduction factor were between 0.38 and 0.61)>Dried apricot(The values of sediment reduction factor were between 0.57 and 1.04).Mountain peach and desert date was the best for soil and water conservation benefits,followed by Ulmus pumila cv.jinye and grassland,the worst was the Dried apricot.From the monthly change,the runoff and sediment reduction's effects of the 5 different vegetation types runoff plots occurred in May.With the increase of rainfall,the cumulative runoff of plot showed a trend of increasing power function,there was significant correlation:The correlation of mountain peach and desert date was the largest,R~2 was 0.93,the correlation of dried apricot was the least,R~2 was 0.56.The cumulative sediment yield increased with the increase of cumulative runoff,the correlation coefficient was between 0.61 and 0.89.(3)Artificial rainfall test of 3 types of soil in Xinjiang showed that:particle composition and soil organic matter concentration were the main factors influencing the difference of soil erodibility(K).The higher silt content was,the higher sediment concentration and K value were,suggesting it was much easier to cause soil erosion.To the contrast,the higher clay content in the soil was,the smaller sediment concentration and K value were,illustrating it was much easier to resist soil erosion.Correlation analysis shown that correlation coefficient of runoff rate and sediment yield was 0.56,and there was no significant correlation relationship.Soil organic matter and cumulative total sediment had a significant correlation relationship,and the correlation coefficient was 0.73.By breaking the soil structure,we found that for the 3types of soils with>2 mm soil structure,runoff rate,sediment yield and K value of Gray calcium soil were all the least;while for soils with<2 mm soil structure,runoff rate,sediment yield and K value of Brown calcium soil were all the least.The ability of resisting erosion of soil with>2 mm soil structure was larger than that of soil with<2 mm soil structure. |
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