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Northwest A&F University (2019)

Response of Runoff and Sediment Yield from Biological Soil Crust Slopes in Loess Hilly Regions to Rainfall Intensity

谢申琦;

Titre : Response of Runoff and Sediment Yield from Biological Soil Crust Slopes in Loess Hilly Regions to Rainfall Intensity

Auteur : 谢申琦;

Grade : Master’s Theses 2019

Université : Northwest A&F University

Résumé partiel
Soil and water loss is the main ecological and environmental problem in loess hilly region.Rainfall is the driving factor of soil and water loss.Since the end of the 20 th century,biological crust has been widely developed in the converted farmland in loess hilly area,which has a significant impact on the yield of slope sand.It is of great scientific and practical significance to pay attention to the response rule of sediment yield and runoff on biological crust slope in loess hilly region to rainfall intensity.Therefore,this paper studies the response of soil erosion from biocrust slope in different coverage and different types to rainfall intensity through indoor and field simulated rainfall experiments.The influence of rainfall intensity and biocrust in soil erosion were compared,and finally the mechanisms the effect of the biocrusts on runoff and sediment yield were further analyzed.In order to clarify the changes and mechanism of the biological soil crust anti-soil erosion with the rainfall intensity,to lay the foundation for the establishment of the soil erosion prediction model considering the biological soil crust factor,the research has achieved the following main results :(1)Rainfall is the driving factor of soil and water loss on biological soil crust slope,and rainfall intensity has a significant impact on the yield of runoff and soil erosion.Rainfall intensity significantly affected runoff and sediment yield from the intact biological crust slopes.When rainfall intensity was 0.83,1.17,1.50,2.00,2.50 mm min-1,biological soil crusts reduced by 78.44 %,69.01 %,66.78 %,49.93 %,20.71 % of runoff yield and 89.99 %,95.20 %,94.94 %,77.13 %,77.03 % of sediment yield compared with bare soil slopes,respectively,indicating that the role of biological soil crusts in decreasing the slope runoff and sediment yield decreased with the increase of rainfall intensity,and the role of biocrusts in decreasing runoff yield was less than decreasing sediment yield.The biocrust slopes can significantly improve the erosion erosive rainstorm standard on the Loess Plateau to 1.50 mm min-1 or above.The threshold value of runoff generation from the complete biological soil crust slopes was 0.71 mm min-1,and the inflection point value was 1.74 mm min-1.Rainfall intensity significantly affected the runoff and sediment yield from biocrust slopes in different coverage and types,and the runoff and sediment yield on the slope were related to the coverage and type of biocrust.The biocrust coverage was about 60 %.When the rain intensity increased from 1.50 mm min-1 to 2 mm min-1,the runoff intensity increased significantly from 0.342 mm min-1 to 0.835 mm min-1 firstly,and the sediment yield rate increased significantly from 4.409 g m-2min-1 to 30.106 g m-2 min-1firstly.The inflection point values of rainfall intensity on the 60 % coverage biocrust slopes about runoff intensity and sediment yield rate were equal or greater than 1.50 mm min-1.The inflection point values of rainfall intensity corresponding to the 20 % coverage biocrust slopes runoff intensity were less than or equal to 1.17 mm mm-1.Therefore,the inflection point values of rainfall intensity corresponding to the runoff and sediment yield of the biological crust slope increased with the increase of the coverage.The effects of biocrust coverage on the runoff and sediment yield on the slopes were phased and not strictly linear.T

Mots clés : Rainfall intensity; biological soil crust; runoff intensity; sediment yield rate;

Présentation (CNKI)

Page publiée le 16 novembre 2019