Study Of Landscape Ecological Planning And Drainage Basin Ecological Management In The Four-Lake Basin

A drainage basin is a certain area where rain flow gathers, or is a drainage basin irrigated by a river. It is a natural catchments unit and has specifically boundary from the source to estuary, and its main feature is the natural distribution of water resources. In a basin, as a entia, close interaction and mutual restriction exists between various natural resources and different regions, and so, only with the integration of ecological protection and construction, can we solve all kinds of problems in a basin. Through the valley ecosystem management, which regards the valley as a unit, we can reduce the soil and water loss can decrease, maintain the sustained productivity of land resources, improve the management level of variety resources in a basin, suffice the needs of ecological water, prevent or reduce the disaster loss, optimize the industrial structure, keep and reinforce the recovery and development of the renewable resources in a valley, promote biological diversity, especially protect and raise rare or endangered species ,coordinate and improve the management of all kinds of resources especially the natural resources and human resources, promote good cycle of ecological and the sustainable and stable development of socio-economic.The landscape ecological planning and landscape ecological construction are the base, means and important part of the valley ecosystem management. The landscape ecological planning makes the optimal program of the landscape resources use on the basis of the landscape ecology analysis, synthesis and evaluation. Its basic task is to coordinate and improve the inner structure and the ecological processes of the valley, deal with the relationships between the resources development and ecological protection, economic development and environmental production, therefore, to improve the landscape ecosystem functions, enhance its anti-disturbed capability and stability, and protect the ecological integrity of the natural world.The Four-lake basin, a tributary of the Yangtze River middle reaches, is located in the hinterland of Jianghan Plain. It was named the Four-lake basin because of the main drainage channel running through four lakes---the Long Lake, the Three Lake, the Egret Lake and the Honghu Lake. It is surrounded by Yangtze River on the directions of the east, the south, the west, and close to Hanjiang River and its tributaries the river of East Jinghe River on the north .The total area of the Four-lake basin is about 11618.51 km~2, on which lived 5million people.In the Four-lake basin, Flood disaster, water pollution and schistosomiasis are the serious ecological environmental problem, which connect closely with the landscape structure and space pattern. For water is the core element and connection bridge, the destruction of the hydrological connection and water cycle will be inevitably lead to unbalance of the valley system's structure and failure of functions which are just the essence and root of the ecological environmental problem of he Four-lake basin.Using the remote sensing and GIS to analyze the landscape structure of he Four-lake basin, the result shows that the proportion of each landscape types differs greatly, and the distributing of wetland landscape is uneven. The fragmentation of the various landscapes is relatively lower. Some large patches, as the minority, become of the main part of the whole area.Furthermore, using the Fractal model, the analysis of complexity and stability of the landscape structure in the Four-lake basin proved that complexity and stability of every landscape types are obvious different each other. Among them, the order of complexity is as below: artificial water, natural water, town, dry land and paddy field. The fractal dimension of the artificial water is the highest, while the structure the most complex. The order of stability is as below: the paddy field, the dry land, town, natural water, and artificial water. The order of the stability is just opposite to that of the complexity, the more complex of the landscape, the more unstable. The analysis of the stability and complexity of the various landscape elements provides evidence to the landscape ecological planning and ecological management in the Four-lake basin.The Markov model and the minimum accumulative resistance model are introduced into the landscape planning of the Four-lake basin. Making use of the Markov model, we can get the result of change trend of the landscape structure in the Four-lake basin: the natural water, the paddy field and the non-wetland (mainly the dry land) reducing, and the artificial water and town increasing obviously.Based on transition probabilities calculated by the Markov model, we can get resistance values of each landscape type which the accumulative minimum resistance model needs, and use geography information system to compute the resistance surface diagrams of lakes, artificial water and towns, and finally, make a correspond planning to the area and concrete distribution of the landscape elements such as the lakes, the artificial water, paddy field, the dry land and towns.There are two cases of The concrete planning: one is according with the result of the Four-lake basin landscape structure predicted by Markov model, because the lake area are almost the same large with the present condition, we call it non-retreating land project. Another case will consider the implement of the measure such as retreating the land to the lake and so on, and the land area will be extended obviously, but the proportion of the paddy field will be comparatively lower, we call it retreating land project.The main measures of the landscape ecological construction and ecological management for the Four-lake basin includes: retreating land to lake and recover the wetland, extending lake and wetland areas; rehabilitating and constructing lake ecosystem; connecting river and lakes and transferring water from river to lakes; eradicating oncomelania ecologically and controlling schistosomiasis synthetically; protecting biodiversity of the Four-lake basin; strengthening the construction of Flood storage area, and building up an exclusive administration agency, giving an overall consideration on construction and management of the Four-lake basin.