Study On Method Determining The Width Of Plant Protection Zone For Soil And Water Conservation

As is provided in Article 18 of Law of the People's Republic of China on Water and Soil Conservation,which was revised in 2010,on the slope and bank of erosion gullys,on both sides of rivers and around the lakes and reservoirs,land-owners and land-users and relevant management units should build plant protection zone.Prohibit the reclamation and development of plant protection zone.However,due to the absence of a clear delineation of the range of plant protection zone,so far,there are certain difficulties to implement this Article.To implement this law,this study preliminarily puts forward a method to determine the width of plant protection zone,where are the slope and bank of erosion gullys,both sides of rivers,around the lakes and reservoirs,through literature collection and expert consultation.The main conclusions of the study include:(1)The determination method of the width of plant protection zone for soil and water conservation on the slope and bank of erosion gully is based on the mathematical model.The mathematical model is composed of three quantitative division indexes,which are the maximum rate of gully head advancement or the maximum rate of gully bank expansion,the time of plant forming protection benefit,and safe distance for potential danger.In addition,the width range of plant protection zone bank of erosion gully is quantitatively estimated according to the related data.(2)The determination method of the width of plant protection zone for soil and water conservation on the bank of river(lake,reservoir)is based on analytic hierarchy process(AHP).The main influence factors of the width of plant protection zone for soil and water conservation on the bank of river(lake,reservoir)include:slope,the request of the water environmental quality,rainfall intensity,soil anti-erosion capability,sediment interception rate,classification of river(lake,reservoir),current scour intensity,vegetation types,land use types of outside the bank,etc.Those are determined by means of AHP.Accordingly,the division index system for the width range of plant protection zone for soil and water conservation on the rank of river(lake,reservoir)is constructed.The corresponding indexes are selected from three aspects:natural geography,interception of sediment and non-point source pollution,and land use.The classification of the width of plant protection zone for soil and water conservation on the rank of river(lake,reservoir)is divided into five grades:small,smaller,medium,larger and large.Besides,the five grades are given specific reference width for actual needs through referring to the existing research results of suitable width of vegetation buffer zone.(3)The paper puts forward some management proposal about plant protection zone for soil and water conservation,which lays the foundation for the formulation and introduction of corresponding protection policies.