Study On The Division Of Key Prevention And Control Areas Of Soil And Water Loss In Hunan Province Based On SOFM Model

The division of key prevention and control areas of soil erosion is an important part of soil and water conservation management,and is also the basis for the study of soil erosion management mode.According to the new soil and water conservation law promulgated in 2011,the division of key control areas is the work that must be carried out in each province at present,and the people's governments at or above the county level should take into account the local economic and social conditions and the current situation of soil erosion,etc.Draw lessons from state-level division results,delimit and announce key prevention area and key control area.Taking Hunan Province as an example,this paper draws the following conclusions:(1)The index system for the division of key control areas in Hunan Province is put forward.On the basis of drawing lessons from the national division and taking into account the present situation of soil and water loss and the economic and social conditions,the paper puts forward the index system for the division of key prevention and control areas according to the local conditions.It is clear that the selection of indexes for the division of key prevention areas in Hunan Province includes forest coverage,slope and concentrated continuous area,and the selection of indicators for the division of key control areas includes the ratio of soil and water loss area,the ratio of soil and water loss area to the ratio of soil and water loss area,The area ratio of sloping farmland and the area of concentrated continuous section.The establishment of the index system lays a foundation for the follow-up prevention and control work.(2)The model of the division of key prevention and control areas in Hunan Province was constructed.This model mainly includes index system selection,index threshold determination,division method calculation and correction test.The construction of quantitative classification method model provides the basis and reference for the division work of key control areas in Hunan province and the province in the exploration stage.(3)Based on the SOFM method,the threshold value of the key control area was determined.The determination of index threshold is the core problem in the division of key control areas,which directly affects the accuracy of the division results.At present,the method of combining quantitative and qualitative analysis is generally chosen,which is characterized by qualitative analysis and lack of objectivity and scientificalness.In order to avoid the problem of inconsistent threshold standard and strong randomness,SOFM method is used to determine the threshold in Hunan Province.By comparing the modified SOFM scheme based on the town unit,we can see that the division accuracy rate is improved from 65.1%to 83.9%,so the SOFM method is feasible.(4)Two kinds of spatial scale to county and town to carry out the key prevention and control area division work.Based on the basic data of vegetation coverage,slope,soil erosion and land use,this paper selects the spatial scale as the division unit of county,town and administrative district,and takes Hunan Province as an example to carry out the division of key control areas based on GIS platform.(5)In view of the ecological environmental problems faced by the key control areas,the paper puts forward the zonal management mode.The key prevention areas are mainly closed,and man-made interference is strictly prohibited;water conservation forests are created vigorously to reduce non-point pollution.Key control areas take small watersheds as units and build protection projects at the gully head,and build water retaining structures such as valley and silt dams in the gullies.Soil and water conservation timber forest and economic forest were created on the barren slope to improve the coverage of forest and grass,reduce surface runoff and build a good livable environment.