Response of Soil and Water Loss to Land Use and Precipitation Changes on the Loess Plateau
[Objective]In order to clarify the law of sediment yield and sediment loss of different land use types under different rainfall types,and to evaluate the benefit of sediment reduction of different land use types under different rainfall types.[Methods]Based on the monitoring data of runoff and soil loss under natural rainfall conditions over 2015-2016 in 31 runoff plots located in the Loess Plateau of China the characteristics of sediment yield and loss in different land use types,including farmlands,abandoned lands,artificial grasslands,natural grasslands,shrublands and artificial forest lands were discussed.The efficiency of runoff and sediment reduction for each land use type under different rainfall types was determined.[Results]The runoff and soil loss of abandoned lands were the largest(30 mm,86 t/hm2)and artificial forest lands were the smallest(8 mm,24 t/hm2)under the annual rainfall scale,and there was no significant difference between other land use types.Through the application of duster analysis a total of 120 rainfall events were categorized into three distinct rainfall types based on criteria that included amount,duration,and maximum intensity of rainfall in a 30-minute period.That is,Rainfall Type Ⅰ:characterised by moderate rainfall duration(749 min),moderate rainfall volume(35.4 mm),and moderate rainfall intensity(16.9 mm/h);Rainfall Type Ⅱ:comprising short-duration rainfall(222 min),moderate rainfall volume(25.2 mm),and intense rainfall intensity(23.8 mm/h);Rainfall Type Ⅲ:involving a long duration of rainfall(1 451 min),substantial rainfall volume(40.6 mm),but low intensity of rainfall(11.5 mm/h).When considering the impact of these types of rainfall within the given scale,the study observed the following trends,for the runoff coefficient,exhibiting Rainfall Type Ⅱ＞Rainfall Type Ⅲ＞Rainfall Type Ⅰ,while for soil loss,exhibiting Rainfall Type Ⅱ＞Rainfall Type Ⅰ＞Rainfall Type Ⅲ.The runoff coefficient of Rainfall Type Ⅰwas significantly higher than that of other land use types,reaching 17.7％,which was 2.36 times that of artificial forest land.There were no significant difference in runoff coefficient under Rainfall Type Ⅱ,and the average runoff coefficient was 19.9％.The runoff coefficient of abandoned lands,artificial grasslands,natural grasslands,and farmlands(average of 14.3％)was significantly higher than that of shrublands and artificial forest lands(averaging at 9.0％).The soil loss of famlands,artificial grasslands,shmblands and artificial forest lands under Rainfall Type Ⅱ(3.94,0.87,1.06,1.08 t/hm2)＞Rainfall Type Ⅰ(1.60,0.60,0.59,0.63 t/hm2)＞Rainfall Type Ⅲ(0.09,0.20,0.06,0.04 t/hm2).[Conclusion]In the Loess Plateau,the artificial forest land was the first choice to control soil and water loss effectively under the condition of medium-low rainfall intensity and medium-long duration rainfall,and the soil and water conservation effect of shrubland and grassland was better under short-duration heavy rainfall.
land usesoil erosionrunoffsediment volumesoil and water conservationthe Loess Plateau
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