Study On The Land Leveling Project Design In Hilly Area Based On Multi-objective Programming Approach

Although there are richer water and heat resources in the hilly areas of southwest China,the contradiction between people and land is sharp due to the fact that it is the agricultural production is restricted by terrain conditions,coupled with densely populated,result in the poor cultivated land quality.Terracing,the beneficial measure for soil conserving and yield increasing,not only stimulate the potential of production,but also effectively promote the development of regional agriculture and the improvement of ecological environment.With the implementation of rural vitalization strategy and the update of the target of agricultural land improvement,land leveling project is still the focus and difficulty in this field.It is practical to study on design of land leveling project for agriculture in hilly areas in the stage of multi-objective comprehensive improvement.The research results can provide reference for the design and implementation of land leveling project in hilly areas.This paper selects a farming field in Beibei of Chongqing as the research object,and puts forward the future development direction of land remediation on the basis of systematically sorting out the evolution of the construction standard of Chinese agricultural land remediation project,rural development strategy and relevant literature of land remediation project.Then,high-precision DEM in the test area,data support for the design of refined land leveling project,was constructed with the help of 3S technology.Next,in combination with Delphi method and analytic hierarchy process(AHP),the evaluation index system of land leveling project was constructed,and the comprehensive evaluation model of the planning and design scheme of agricultural land leveling project is established.Finally,the spatial analysis and statistics function of ArcGIS was used to replot the farmland,and the relevant indexes were calculated,which could used to evaluate the design scheme.The main research results of this paper are as follows:(1)At present,there are mainly two problems in the construction standard of land improvement projects in China: on the one hand,the slowing updated,result in lagging behind the transformation and development of land improvement;On the other hand,regional characteristics are not prominent,resulting in the lack of guidance and pertinence of local land improvement projects.In order to optimize the construction standard of land improvement project,this paper sorts out the objectives of land improvement in the future,and provides a clear direction for the design and implementation of land leveling project.(2)With the help of RTK technology and UAV platform,the control points(GCPs)and images in the test area were collected,and a high-precision DEM was created based on PixDmapper.The error of DEM is 0.03125 m,which meets the first-level requirements of 1:500 digital elevation model mapping accuracy,and can be used in the study of refined land leveling engineering design.Next,based on the spatial analysis and statistical function of ArcGIS,the terraced fields in the test area were reclassified into 2 and 3 stepped levels by Natural Breaks,Equal Interval and Geometrical Interval classification respectively under the constraint of reference value of horizontal terrace section size.Taking the average elevation of each field as the design elevation of the terraced fields,the reconstruction of high-precision DEM in the test area was realized.(3)According to the comprehensive principle,the principle of relative independence.Delphi method was adopted to select the average width of field,variation coefficient of field size,mean deviation of fields,mean slope of test area,quantities per unit area,landscape fragmentation and shape metrics as the evaluation indexes of land leveling project in hilly areas,so as to construct the evaluation index system of land leveling project.The comprehensive evaluation model of land leveling project design in hilly area is constructed by using analytic hierarchy process.The weight of each index relative to the total target is calculated to be 0.07,0.12,0.30,0.17,0.26,0.06,0.02,which provides a comparison basis for the design scheme of land leveling project.The evaluation parameters were standardized and the comprehensive evaluation scores of the six land leveling schemes under the multi-objective planning were calculated as 0.35,0.30,0.55,0.66,0.47 and 0.64,respectively,by using linear weighing-sum method.The results show that the current construction codes related to land improvement are updated slowly and the regional characteristics are not prominent.This study provides reference for the revision of relevant codes related to land improvement.The establishment of high-precision DEM and terraces redrew in hilly areas can be realized with the support of 3S technology,which provides basic data support for the design of refined land leveling project.By defining the objectives of land leveling project and constructing a comprehensive evaluation system for design schemes of multi-objective land leveling project,the design scheme selection of land leveling project in hilly areas can be realized on the basis of GIS spatial analysis.