| South-North Water Transfer Project is one of large-scale strategic projects of trans-basin water resouces allocation in China's economic constraction. It's building in have great significance to alleviate the grim situation on lack of water resources in North China plain and improve Reservoir watershed ecological environment. As the largest drinking water protection area in China and water source of South-North Water Transfer Project, Danjiangkou reservoir is a major hub Connecting the upper reaches of Hanjiang River and the Hanjiang River middle and lower reaches. Since the age of 70s Danjiangko-u reservoir operation, there are many problems such as:the unreasonable distribution and utilization of land resources, weakness of Ecological basis and some other environmental problems. In this study, Danjiangkou reservoir that involves Danjiangkou City, Yun County, Yunxi County, Shiyan City (including the Wudang Mountain) in Hubei Province and Xichuan County, Xixia County in Henan Province is used as a case study area to monitor, analysis and compare the pre-and post utilized condition of the land resources and the dynamic changes. Based on this we evaluate and study the ecological suitability and vulnerability of land resources to provide a scientific basis of eco-building, agricultu-ral production and sustainable land use. The main conclusions are as follows:(1) Land use structure of reservoir generate substantial changes. The sharpest change in 10 kinds of land-use types, is a total reduction of 7.36 percentage points of the drylands. Followed by the shrub, woodland, grassland and rural residential land, the rate of increase of the total area is 6.6 percentage points. Unused land, urban residential land and water areas increase to a lesser extents which are all less than 0.5 percentage points. Paddy field area take an average annual reduction of 0.02 percentage points. Cartilage change slightly with 0.02 percentage points in number.(2) 17-year period, in addition to paddy fields and dry lands, other land use types ha-ve shown an increasing trend, in which the growth rate of rural residential land is in the largest 12.85%/a. Followed by urban residential land, the annual growth rate is 7.47%. The growth rate of grassland, unused land and shrub are respectively 1.76%/a,1.73%/a and 1.34%/a. Other land use types have small annual rate of change. This shows that the rapid increasing of residential land caused by population growth has an impact on reserv-oir's land-use.(3) Three periods of land use degree comprehensive analysis shows that there was a small increase in the degree of land use between 1990～2000, which is closely linked to the local economic development, urban and rural land expansion. While after 2000 to 2007, the reservoir area degree of land use show volatility trend downward because of implementation of returning farmlands to forests policy and land reduction significantly.(4) Roll in volumes of woodland and grassland are both greater than roll out and the contributions to their increase from dry land are close to 50%. Roll in areas of dry lands and paddy fields are 3.25 and 82.08 times more than the roll out areas respectively. The amount of dry lands'transfermation to woodland, scrub and grassland are more than half of the total transfer volumes. Roll in areas of rural and urban residential lands are 171.96 and 13.88 times more than the roll out areas respectively. The implementation of reservoir ecological restoration and afforestation effectively increase forest area and improve the ecological environment. This is also one of the major driving forces that result in reducti-on of arable land. As the rapid economic development of reservoir area, rural and urban residential lands expand expeditiously. This process will inevitably bring about profound changes in land use. The rate of non-agricultural transformation of farmlands accelerate. In the process of urbanization, the loss of arable land is a important one of the main contradiction between human and land.(5) The typical land-use types are superimposed with the slope and elevation classifi-cation map, which shows that orchards, paddy fields, dry lands, unused land, shrub and grassland are mostly distributed in the 0°～5°flat area. Most woodland distribute the slop of 15°～25°. Paddy fields, dry land, orchards and unused land mainly concentrate in the 0-300m elevation with the distribution area more than 50%. Grassland mainly distribute in the 0-500m elevation area and shrubs mainly distribute the elevation of 0-800m. The distribution of woodland in the region above 500m is up to 70%.(6)Based on the pattern of pressure-states-responses model, the paper evaluates land resource ecological security of the countries and cities of Danjiangkou reservoir. The result shows:the ecological security indices of Xixia country,Danjiangkou city and Yun country are respectively 0.8637,0.7851 and 0.7575. Their ecological environment is in the state of security. On the other hand, the ecological security indices of Xichuan country and Yunxi country are 0.7333 and 0.6751. They are in the state of warning, whose ecological environment security are sensitive. Therefore, in the future work of building Danjiangkou reservoir, we remain the strengthening of the ecological environment construction. |
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