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| Grading of soil erosion intensity in Southwest karst area of China |
| Cao Jianhua1,Jiang Zhongcheng1,Yang Desheng2,Pei Jianguo1,Yang Hui1,Luo Weiqun1 |
| 1.Karst Institute of Geology,CAGS,Key Laboratory of Karst Dynamics,MLR,541004,Guilin,Guangxi;2.Pear River Water Resources Commission,MWR,510611,Guangzhou: China |
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Abstract The concentration of acid insolvable matter in carbonate rock is very low in Southwest area of China.Consequently,the formation of limestone soil is slow and the soil layer is usually thin on karst slope,and the soil loss intensity is mostly weak and light.In fact,the area of rocky desertification in karst region, is continuously increasing these years,and with the soil erosion,the ecological situation is going to worse.The traditional standard for soil erosion gradation is confronted with challenge.The risk valuation and intensity classification of soil erosion in karst region should be redefinition.Depending on the factors on the limestone soil formation and carbonate rock corrosion,related data and images have been collected.With the help of ArcView3.2,the rate of limestone soil formation image can be produced.When the rate of limestone soil formation considered as the soil loss tolerance,a new standard for soil erosion gradation suitable to karst region was put forward.The duration of feeble,light,middle,strong,very strong,and acute soil loss gradation is 1 000 t/(km2·a) respectively.Meanwhile, on the basis of features of soil loss process and karst environment,four suggestions for soil conservation in karst region are also put forward: 1) depending on the karst hydrological characters,the sinkholes and dolines is the key part to prevent the soil loss,and effective measurement for soil protection should be taken;2) on top part of karst hill,the carbonate rock is largely exposed and there is a little soil cover,the way to close hillside to facilitate afforestation should be selected;on the middle part of slope,the rocky desertification of which is middle gradation,the economic plants to increase the land productivity,should be planted;in the foothill part,there are thick soil layer,the farmland construction,modern agriculture activity and food production should be taken;3) in the karst region with thin soil layer,biogenic fence technology is recommended;4) the research of soil melioration technology should be strengthened.
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Received: 08 September 2008
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