| Since the orderly control of soil erosion in China,the current situation of soil erosion and the ecological environment has been significantly improved.Although the relevant researches on the evaluation of technical benefits and suitability of soil and water conservation has been studied,there are still some problems in the evaluation of soil and water conservation technology,such as the low suitability of evaluation index and model method.At present,the research on the evaluation of soil and water conservation technology mainly focuses on the benefit evaluation,which fails to fully reveal the essence of soil and water conservation technology.Based on this,this paper defines the connotation of soil and water conservation technology,analyses the characteristics of soil and water conservation technology,and clarifies the background and evolution trend of soil and water conservation technology through the analysis of eco-economic related issues arising from soil and water conservation technology.At the same time,the evaluation index of soil and water conservation technology,evaluation model and method under different situations were constructed.And we take the Zhifanggou watershed with the complete evolution process of ‘destruction-restoration-destruction-restoration' as an example,the evolution process of soil and water conservation technology in the watershed was evaluated.And finally,the evaluation system of soil and water conservation technology was validated.The main conclusions are as follows:(1)This paper defines the conception of soil and water conservation technology,clarifies the characteristics of soil and water conservation technology and the types of soil and water conservation technology in Zhifanggou watershed.Soil and water conservation technology refers to a series of technologies used in soil erosion areas,using the theory of soil and water conservation and the theory of ecological economy and other related disciplines,aiming at soil and water conservation,optimizing the allocation of water and soil resources,and coordinating the development of agro-ecological resources and industries,which including soil and water conservation engineering technology,soil and water conservation farming techniques and soil and water conservation biotechnology.The characteristics of soil and water conservation technology are as follows:(1)the core purpose of soil and water conservation technology is water storage and soil conservation;(2)soil and water conservation technology should depend on specific material carriers;(3)soil and water conservation technology is a comprehensive technology involving many disciplines;(4)soil and water conservation technology has three attributes: natural,economic and social.(2)The background of selection of soil and water conservation technology was clarified.The selection of soil and water conservation technology is restricted by social,ecological and economic factors.Under the constraints of macro-factors such as ecological management,regional economic development and national policies,the working principles and implementation process of soil and water conservation technology are constantly improving,and the matching degree with regional ecological,economic and social conditions is getting higher and higher.There was different directions in the implementation process of various soil and water conservation technologies.The soil and water conservation engineering technology aims at changing micro-topography to prevent soil and water loss;soil and water conservation tillage technology aims at water conservation,soil conservation,fertilizer conservation,soil improvement and crop yield improvement;soil and water conservation biotechnology aims at increasing effective vegetation cover on the ground and soil and water conservation.Finally,economic,social and ecological benefits will be unified.(3)The evaluation system of soil and water conservation technology is constructed,which including index system,evaluation method and evaluation model.The evaluation model depends on the research results of topic 4.The index system includes five first-level indicators,14 second-level indicators and 29 third-level indicators.Each index is divided into five scales,and the corresponding indicators are interpreted.Water and soil conservation technology is evaluated in three different situations.The weights of the first and second indicators are calculated by analytic hierarchy process.Among the first indicators,the weights of technical suitability are the highest(0.2983),and the weights of the second indicators are the highest(0.6578).Logistic regression analysis was used to get the regression coefficients of the three-level indicators,and the regression coefficients of climate suitability were the highest,which was 1.1730.There are three scenarios in the evaluation model: scenario I is that the evaluation experts have a macro-understanding of the assessed objects,but there is no data support.The first-level indicators are used to build the analytic hierarchy process model and scenario II is that the evaluation experts have a deeper understanding of the assessed objects,but there is not enough data support.The second-level indicators are used to build the analytic hierarchy process model and scenario III are sufficient data support.Logistic regression model was established for the grade index.(4)In the past 70 years,the selection and use of soil and water conservation in Zhifanggou watershed have gone through three stages.From 1973 to 1983(Phase I),soil erosion control was mainly based on Soil and water conservation tillage technology,supplemented by engineering technology and a small amount of biotechnology,and the ecosystem was in an unstable recovery period.From 1984 to 1998(Phase II),soil and water conservation engineering technology and biotechnology were the main methods to control soil and water loss,supplemented by farming technology,and the ecosystem was in a stable recovery period.From 1999 to 1999(Phase III),water and soil conservation biotechnology is the main technology for water and soil conservation,and engineering and farming technology are the supplementary and supporting technology system.Ecosystem is in the period of stable recovery and functional upgrading,and each stage has formed a technological system matching its ecological,economic and social background.(5)Based on the sub-scenario assessment of soil and water conservation technology system in each stage of Zhifanggou watershed,the following conclusions are drawn:(1)The evaluation results under different scenarios are consistent with the measured values,and the evaluation system of soil and water conservation technology is validated.(2)The difference between the calculated and measured values in the first stage of the basin is larger than that in the second and third stages.This result may be due to the long distance between the first stage and the survey,the vague memory of the subjects and the imperfect records of the relevant data.(3)The evaluation results under the three scenarios are on the rise,indicating that the technical system of water and soil conservation in the basin is constantly improving and gradually optimizing,which is consistent with the actual results of the survey. |
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