| Soil erosion is one of the most serious global environmental problems, have serious repercussions to the global and regional ecological environment. The southwest China karst area is the world’s largest karst exposed even Area, an area of about6.2×105km2, with complex geological conditions in the region, karst is well developed, constitutes a unique "dual structure", a variety of landforms, a fragile ecological environment anti-jamming capability; karst Areas of Southwest China’s ethnic minorities and the poor are concentrated, long-term socio-economic backwardness of the local ecological environment protection and construction; fragile ecological environment and irrational human activities, making the region the situation is very serious soil erosion, and many places even the soilless flow rocky desertification situation, the local ecological environment and ecological safety of the serious challenges caused serious harm to the regional socio-economic development.As one of the Karst Areas of Southwest Guangxi region in hilly red soil and karst landform widespread soil erosion in an area of2.81km2, accounting for 11.87%of the total land area, severe soil erosion leading to a lot of land surface soil have been depleted not usein some areas has been a direct threat to the survival of the local people, facing a dual crisis of ecology and the poverty and backwardness; soil erosion brought about by sediment causing siltation of rivers, channels and reservoirs, exacerbated by the occurrence of floods and droughts; soil erosionhas become a serious constraint to economic and social sustainable development of Guangxi. The size distribution of the Guangxi Water Resources Department to explore Guangxi soil erosion and rocky desertification and soil erosion processes and the formation and evolution mechanism, scientific prediction of soil erosion, evaluation, carried out in cooperation with the Institute of Karst Geology of the Lijiang River Basin Soil Erosion Remote Sensing Research and ecological base construction projects; this study as an opportunity to select Zhaidi underground river basin study, carried out the study of soil erosion monitoring.Through the Zhaidi underground river basin soil erosion monitoring in this paper, the use of traditional monitor and improve the model to monitor a combination of methods, carried out a detailed analysis of the influencing factors of soil erosion in karst areas, the use of field monitoring and3S technology to extract the monitoring indicatorsin order to estimate watershed soil erosion, and regional soil erosion sensitivity analysis, build the karst small watershed soil erosion monitoring system.The main conclusions are as follows:(1) Through the traditional method of river sediment yield to watershed soil erosion monitoring results showed that:in2010, Zhaidi underground river basins total exports sediment output2013.6t, Basin Mainland export of sediment sediment output2922.8lt between909.2lt gap; description of the karst and of soil erosion, sediment and can not be fully brought out from the underground river exports, the reason should be part of the sediment to precipitate in the underground river; from the data calculated by the underground river basin, about30percent of the sediment left in the underground river system.(2) Calculated for the karst small watershed soil erodibility factor improved land use patterns as a basis for the calculation of the K factor; monitoring the watershed soil erosion through the RUSLE model approach, the results show that:Zhaidi underground river basin, average annual total soil loss for16655.44t, the average annual erosion modulus504.7lt/(km2·a); in accordance with the division of the karst area comprehensive soil erosion control technical standards (SL461-2009), Zhaidi underground river basin soil erosion intensity is moderate, the average annual soil erosion modulus of about karst areas of soil loss tolerance (50t/(km2·a))10times.(3) The results of the two methods quite different results based on the calculation of the sediment output is only calculated based on the RUSLE model results from12%to18%; soil erosion based on exports of the underground river, Soil erosion of Zhaidi underground river basin is mild intensity, while soil erosion estimates based on the RUSLE equation Zhaidi underground river basin soil erosion intensity is moderate; RUSLE equation-based soil erosion estimates more in line with the results of the Chinese water and soilloss and ecological safety inspection (from July2005to May2007)".(4) In the karst area of soil erosion spatial pattern analysis, the concept of "unit factor affecting the rate" to value the size of the impact of soil erosion factors, such as elevation, slope, vegetation cover, land use,extent of the effects of erosion of karst areas.(5) Through the sensitivity analysis on t Zhaidi underground river basins soil erosion, has been the most sensitive areas of the basin Mainland lower river at the exit for soil erosion, soil erosion in the area of governance and regional ecological protection should be noted that exports to the underground riverthe region’s soil and water conservation and protection of ecological environment.(6) Based on monitoring the implementation of soil erosion in the traditional monitoring and modeling, and analysis of soil erosion on Zhaidi underground river basin, from the goals, targets and implementation of three levels of soil erosion monitoring system is discussed through the land and water based on database technologyloss of monitoring information platform for the discussion of karst small watershed soil erosion monitoring system.The main innovations are as follows:(1) Karst small watershed soil erosion monitoring, obtained about30%of the sediment in the process of soil erosion (relative to the total loss of small watershed soil) to stay in the underground river system;(2) Based on land use, with the experimental method,improved the RUSLE equation soil erodibility factor K value calculated RUSLE more applicable in the karst area;(3) To represent a variety of environmental factors, the impact on soil erosion, soil erosion the unit factors affect rate concept can be used to characterize the size of the number of different factors impact on soil erosion;(4) The application of multi-factor analysis, combined with RS and GIS technology to evaluate the sensitivity of the study area soil erosion, give full consideration to the potential risk of soil erosion in the different ecological environments combination of factors, a high level of credibility. |
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