| This paper analyzes the problems faced by the evaluation of ecological control technology from 4 aspects:evaluation basis,evaluation principle,evaluation idea and evaluation process,and initially forms the evaluation theory of ecological technology.It is firstly proposed that eco-technology should be evaluated from 3 dimensions:time dimension,space dimension and technology dimension,respectively.Based on the comprehensive comparison of various evaluation methods,and the acquisition of related data in the study area,the analytic hierarchy process(AHP)method,canonical correlation analysis(CCA)method,fuzzy comprehensive evaluation(FCE)method,technique for order preference by similarity to an ideal solution(TOPSIS)method,rough set theory(RST)method and other methods are selected to evaluate the application effect of ecological control technology in China according to the problems in different regions,such as soil erosion in the earth rock mountain area in North China,soil desertification in the Beijing-Tianjin sandstorm source areas,land degredation in the South Rocky areas and soil and water loss in the Loess Plateau areas.The main ecological control technologies in these regions are sorted out,and the comprehensive evaluation of the common ecological control technologies in different regions provide the basis for the future ecological control projects.The main conclusions obtained in different regions are as follows:(1)Common water and soil conservation measures in the chestnut forests include level ditch,level terrace,wood brace,ridge,moss cover,grass cover,agriculture and forestry intercropping,etc.Due to the serious problems of chestnut production mode and farmers' aging,the commonly used measures in this areas are level ditch,ridge and wood brace.According to the investigation,the effect of wood brace on reducing runoff and sediment is not ideal.The canonical correlation analysis showed that the soil erosion characteristic factors of chestnut forest were affected differently by rainfall factors under different control measures.Under the action of level ditch and ridge,the soil erosion from chestnut forest was greatly affected by the maximum rainfall intensity 30 minutes(I30),while under the condition of no measures,it was mainly affected by rainfall.Therefore,we put forward the following suggestions to improve the production and management of chestnut forests.On the scale of small watershed,soil erosion control technologies,such as grass covering and intercropping,are adopted to improve the natural recovery of other chestnut forests.On the scale of slope,engineering measures(level ditch or ridge)and biological measures(moss coverage or grass coverage)are adopted to achieve the cooperation between soil and water conservation measures in the slopes and among the watershed.(2)In the past 70 years since the founding of the people's Republic of China,we have explored many kinds of sand control measures,including plant sand barrier,mechanical sand barrier,sand sealing and grass cultivation,mechanical sand barrier and shrub planting.At present,the indicators used in the evaluation of the implementation effect of sand barrier technology are not scientific and comprehensive.In this study,14 secondary indicators and 25 tertiary indicators are selected based on the literature frequency method and AHP method,and the evaluation index system of sand barrier technology is constructed.The index system takes technical benefit as the leading factor and takes both functional and applied comprehensive evaluation into consideration,so as to comprehensively evaluate sand barrier technology in the Beijing-Tianjin sandstorm source areas.Six sand barrier technologies were evaluated and sequenced by using the hierarchical fuzzy integral model.Finally,wheat straw sand barrier,straw sand barrier,clay sand barrier,gravel sand barrier,plastic sand barrier and sandbag sand barrier were selected with better economy,technical performance and environmental benefit,which can provide a reference for the construction of sand fixing engineering.(3)For the problem of rocky desertification in South karst area,China,the main control measures are closed cultivation,economic forest,fine forage,stone to terrace,hedgerow,land preparation,forage silage,drainage and water interception and energy development.It is difficult to achieve ideal results with single control measures.This study chooses three control modes(plant protection engineering,slope to terrace engineering and enclosure)to evaluate.TOPSIS method and entropy weight method are used to evaluate the existing main ecological control modes in the southern karst areas,and the analytic hierarchy process was used to construct the evaluation index system of the ecological control mode in karst areas,then the evaluation criteria of each index were determined.Entropy weight method is used to determine the weight of evaluation index of ecological control modes.Plant protection engineering is the best mode,followed by slope to terrace engineering,and the last mode for enclosure.Combined with the engineering measures such as fish scale pit and level terrace,water and soil conservation forests and economic forests can provide effective protection for the control of rocky desertification in karst areas.(4)Soil and water loss control measures in Loess Plateau can be divided into small watershed comprehensive control technology and regional comprehensive control technology according to the control scope;according to the control object,it can be divided into slope control technology and ditch engineering technology,mine repair technology and reservoir greening technology.A two-level evaluation index system framework of soil and water loss ecological control technology in the Loess Plateau is established,and the factors affecting soil and water loss ecological control technology are analyzed from 4 aspects:technical maturity,technical application difficulty,technical benefit and technical promotion potential,including 12 two-level indexes;In the case analysis of ecological control technology,the terrace,dam land,afforestation,grass planting,economic forest and enclosure are included.Based on the classification function of indiscernible relation of rough set theory,the index is selected by attribute reduction method,and the evaluation index system of ecological control technology of soil and water loss in the Loess Plateau is constructed,which is composed of 4 first-level indexes and 7 second-level indexes;then the weight of each index is obtained by the information granularity,and according to the principle of attribute importance,the weight of each secondary index is calculated,then the comprehensive weight of each index is given.Finally,the comprehensive evaluation results of six ecological control technologies are obtained by using the weighted method,that is,economic forest(11.67)>dam land(11.17)>terrace(11.00)>grass(9.67)>afforestation(9.17)>closure(8.67). |
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