Impacts of Rainfall Characteristics and Vegetation Cover Patterns on Slope Runoff and Sediment Yields in the Three Gorges Reservoir Area
[Objective]This study was aimed to explore the impacts of rainfall characteristics and vegetation cover patterns on slope hillslope runoff and sediment yields in the Three Gorges Reservoir area,and to adapt to the new needs of the prominent contradiction between man and land and the development of rural industries for the optimal utilization of underforest land resources.[Methods]Taking a typical fallow forest in the Three Gorges Reservoir area as the research object,four runoff plots with full-slope herbaceous cover(QF),upper-slope bare ground+lower-slope herbaceous cover(XF),equidistant herbaceous strip cover(TF),and full-slope herbless coverage(WF),were set up to carry out field observation of slope runoff and sand production in 24 erosive rainfall events and to identify the effects of erosive rainfall and vegetation cover patterns on hillslope runoff and sediment yields.[Results](1)The 24 erosive rainfall events were classified into three categories,including A-type(small rainfall,heavy rainfall intensity,and short duration),B-type(large rainfall,heavy rainfall intensity,and short duration),and C-type(small rainfall,light rainfall intensity,and long duration).A-type was the rain type with the highest occurrence frequency at 45.83％.The cumulative rainfall of B-type was the largest,accounting for 63.44％of the total rainfall.(2)The cumulative runoff depth and cumulative erosion volume of the four vegetation cover patterns generally showed QF＜XF＜TF＜WF;The peak value of runoff depth and erosion volume all occurred in B-type rainfall,which led to an increase in runoff depth of 337.74％～410.32％and an increase in erosion volume of 283.47％～504.58％compared to A-type rainfall.(3)The proportion of runoff depth and erosion amount produced by the WF was 75.75％and 98.51％,while XF and TF accounted for only 12.20％and 1.08％,7.28％and 0.34％,respectively.Compared with WF,the runoff interception and reduction of XF and TF were 84.18％and 75.85％,and the sediment interception and reduction were 96.99％and 93.30％,respectively.[Conclusion]By comparing the runoff and sediment yields of runoff plots under different vegetation cover patterns,it was found that the modes of upper-slope tillage+lower-slope 1 herbaceous coverage,strip tillage+contour hedgerow can take into account the functions of water regulation and soil conservation of forest land and ecological planting of understory,which can provide a theoretical basis for ecological restoration and the optimal utilization of understory land resources in the Three Gorges Reservoir area.
soil erosionerosive rainfallvegetation cover patternecological restorationThree Gorges Reservoir area
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