Study On Application Of Multi-objective Optimizing Method In Comprehensive Treatment For MoGou Small Valley

In Danjiangkou Reservoir and its upstream catchment areas, There is serious soil erosion which almost takes up one tenth loss of Yangtze River basin area, even leads to the sudden flash floods and mudslides disasters somewhere, water and soil loss phenomenon not only badly constrains sustainable economic and social development of the catchment area, but also influences the water quality safety of South-North water diversion midline project.Multiple objectives planning method, is superior to single objective planning, not only avoids artificial experience of subjective decision-making factors, but also meets demand of each target at the same time. Weighted coefficients method, is also named as linear weight sum, It's train of thought is: according to the degree of importance of the goals given their different weights, the weighted sum objective function, is regarded as a new target, So this multi-objective problem can be changed into a single goal, Solving this single objective problem, can get solution of the multi-objective problem.The purpose of researchThis research objective for Mogou small valley, which is on the upper reaches of the west side in the Danjiangkou reservoir. There are serious soil erosion and frequent floods in the valley to restrict seriously the sustainable economic and social development, along with soil erosion, chemical fertilizer, pesticide residues and other chemical composition once flow into the Danjiangkou Reservoir, water quality safety of the middle route project will seriously be affected. By engineering measures, ecological measures, exclusion, and land-use adjustment, the integrated watershed management and planning, which can curb soil erosion, adjust the industrial structure and realize farmers income increasement, affluent life of the masses, the harmony between man and nature, the sustainable economic development in the valley, to ensure the delivery of superb water sources to Beijing.The Method of researchThrough application of multiple objective planning method, mathematic model is established, regarding direct economic benefits, and soil efficiency, capital input as the objective functions. Different Weighted coefficients are conferred to different objective functions, which can change the multi-objective problem into a single objective problem. Solving the single objective problem will get various benefits of the small watershed planning: economic efficiency, water and soil benefits, social benefits. The national economy rating is done in order to show it's rationality from both static and dynamic perspectives, with the index such as net present value, invested payback period, benefit-cost ratio, internal rate of return. At the same time, the qualitative evaluation is done about soil and water conservation ecological benefits, social benefits.The fruits of researchBy vigorous development of soil and water conservation forest and actively implementing the ecological restoration, forest and grass coverage rate will be improved from present 82.9 percent to 87.6 percent, and man-made soil erosion will be under controlled, changing open forest land into forest land by replanting or blocked by management. Soil erosion control area will be 9.25 km2 and management level will reach 100 percent, which will retain sediment in the rate of 70 percent to national acceptable criteria to ensure water quality safety in water areasWith its own characteristics and local people's aspirations, by the measures such as adjusting agricultural structure, turning present sloping land to all economic forest or ecological forest, and vigorously developing fruit forests, which can enhance economic efficiency, increase people's incomes, and make per capita net income of the project area more 30 percent than local average level, as well as per capita grain output will reach 400 kg and above, to meet local farmers' requirements for foodstuffs.Conclusions of the researchA new academic method is practiced to broaden application scopes and fields of the method, through application multi-objective planning method in the valley.