| The relatively fast population growth, over-used land resources, irrational development, deterioration of ecological environment, and increasing ecological fragility in Yangtze River Basin increased drought, soil erosion and land rocky desertification. The fundamental causes of ecological problems in Yangtze River Basin is the damage of natural environment, especially the destruction of farmland and forest vegetation caused by deforestation. Therefore, ecology barrier construction in Yangtze River Basin is to maintain the stability and security of ecosystem function and the fundamental ecological security in Yangtze River Basin and the adjacent region. The’barrier’ in regional ecological barrier construction mainly focus on the ecological protection in and around the construction area, to act as a key role to prevent soil erosion, regulate the water cycle, improve the regional ecological service function, and enhance the hydrological regulation in underlying surface.At present, most of the ecology barrier construction researches are carried out from the qualitative aspects of matter and energy cycle, structure function and spatial scales, but lack of specific systematical research about ecological barrier construction method; while few studies concerning the effects of ecological barrier construction on hydrology. Unlike traditional afforestation or forest/grass recovery project, based on the basic theory of ecology recovery, landscape ecology and hydrology, taking remote sensing and geographical information technology as technical support, the ecohydrological evolution of Yangtze River Basin (from Yibin to Chongqing) was comprehensively analyzed. Combined with land suitability evaluation, location characteristic analysis result, ecological barrier construction planning area was extracted and the ecological barrier construction plan was set up. Based on the value equivalent method, the accounting value of ecosystem services under different ecological barrier construction program was checked, and select the best program as the final program of ecological barrier construction, and simulate hydrological effects of ecological barrier construction under the program. Through regional ecological barrier construction, on the basis of the comprehension of engineering and non-engineering measures, based on the optimization of regional ecological patterns and reasonable adjustments to the land use structure, and improved the vegetation cover rate and the basic meaning of innovation and ecological barrier construction, at last, proposed a location characteristics analysis method to analyze the local characteristics of regional socio-economic and ecology. Specific results are as follows:(1) Ecological hydrological temporal evolution recognition. Select MODIS remote sensing data in typical month (August) from 2000 to 2014 to analyze regional vegetation NDVI change. The results show that the Yangtze River Basin (from Yibin to Chongqing) vegetation growth has an overall downward trend. The annual average spatial distribution of vegetation cover in typical month is significant. Based on the measured meteorological and hydrological data to analyze the precipitation evolution during 2001-2010 and evaporation changes during 1961-2001. The results indicate that the regional precipitation and evaporation shows a decreasing trend. Taking fitting analysis of runoff data of hydrological stations in typical river cross-section, for the past 30 years, the average annual runoff of tributary in the north upstream of Yangtze River (from Yibin to Chongqing) shows a overall decreasing trend, but the annual runoff in mainstream and tributaries in the south of mainstream show an overall increasing trend.(2) The ecological barrier construction plan. Propose an area feature analysis method of radial zoning, and use ArcGIS tools to analyze regional social and economic characteristics of the environment and ecological features. The results show an intensive population and economy, high degree of land use, natural vegetation cover in Yangtze River basin (from Yibin to Chongqing). In this study, land suitability and location features were evaluated, taking Yangtze river mainstream/tributary buffering area, main road buffering area and economic development plan area as the base map, to determine the ecological barrier construction planning area of about 146,300 km2; based on the topography and vegetation characteristics data, combined with the mountainous area distribution of rock desertification, taking improving the vegetation coverage slope farmland as the goal, to set up different ecological barrier construction programs.(3) Optimal selection of ecological barrier construction scheme based on ecosystem services of accounting. Innovated ecological barrier slope rating construction. Using equivalent value of ecosystem services to account the status of the ecological barrier area and the value of ecosystem functions and services under different construction program. The results show that the ecological barrier construction can effectively improve the regional ecological service function value. After the comparison of total amount of functional value of different ecosystem services plans to determine slope classification construction as the best plan.(4) Assessment of the effects of ecological barrier construction on hydrology. Construct SWAT hydrological model, through the simulation of runoff changes in month scales, to assess the model applicability, to further simulate the hydrological changing process under the regional ecological barrier construction program. The simulation results show that the average annual runoff in Yangtze River basin upstream (from Yibin to Chongqing) reduce significantly; there are some differences in surface runoff change in different sub-typical river basin clusters. Ecological barrier construction has a significant effect on the dry season and wet period runoff regulation. Ecological barrier construction increase the overall watershed evapotranspiration, also, the soil water flow showed a certain degree of increase. Overall, ecology barrier construction can reduce the regional surface runoff, increase regional evapotranspiration and soil water flow, and effectively improve the regional soil water conservation and prevent soil erosion.The application of research on Yangtze River Basin can not only directly provide methods of support for the restorative construction and protective planning of ecological environmental degradation, but also to provide a scientific basis for the development of the Yangtze River economic belt, having a significant practical significance. |
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