Study On Agricultural Water Resources Carrying Capacity In North Large-Scale Irrigation Area

The large-scale irrigation area in the north China plays a crucial role in protecting national food security and maintaining the environment and keeping development of regional economy. The agricultural water resources is not only an important support condition for the survival and development of irrigation, but also the controlling factor for maintaining the sound development of environment in irrigation area. It's great significance for sustainable development of large-scale irrigation area in the north that scientific assessment of carrying capacity of agricultural water resources and handling the ralationship between social, economic and ecological environment and water resources in irrigation area .This thesis besed on the analysis of the fatures of the agricultural water resources in large-scale irrigation area in the north, reserched on the assessment of the theory and method of carrying capacity of the agricultural water resources in large-scale irrigation area in the north from a systematic analysis viewpoint . Main contents and results are as follows:(1) An analysis on the research development of the carrying capacity of water resources of regional at home and abroad was made . The previous research results was learned from and combined with the characteristics of the agricultural water resources in large-scale irrigation area in the north the concept of carrying capacity of agricultural water resources in irrigation area was defined, and the contents, characteristics, theory and evaluation methods of carrying capacity of agricultural water resources discussed in depth .(2) In the principle of sustainable development, based on ecological economic theory and the hydrological cycle theory of natural and artificial binary mode, an analysis on the structure of complex system of irrigation water resouces and social economic and ecological, and the giant complex irrigation system is divided into water resource subsystem, social subsystem, economic subsystem, environment subsystem. The system dynamics and application software Vensim PLE were applied to built for forecasting SD model of supply and demand of water resouces in irrigation area..(3) In accordance with the principles of evaluation index system, the assessment system of two leves agricultural water resources carrying capacity were built. The weights at all levels were fixed through the expert scoring method and AHP. The application of fuzzy comprehensive evaluation method and set the analytical method on carrying capacity assessment in agricultural water resources in irrigation area were analysis and discussed.(4) Baoji Gorge irrigation in Shaanxi, for example, in 2005 the base year for the planning, the water supply and demand conditions from 2006 to 2020 is predicted under the two irrigation programs (Trend-type programs and water-saving programs) . Results indicated that the use of the program in 1(trend-based programs), agruculture water resouces was shortage in irrigation area during the the planning level year, the obvious contradiction between supply and demand; wnen the program 2 (water-saving programs) was adopted, water supply and demand in irrigation district can be kept balance during the planning level year.(5) On the basis of the results in program 2 (water-saving programs), the assessment for the carrying capacity of agricultural water resources in Baojixia irrigation district were made according to the established set of fuzzy comprehensive evaluation method and the analytical method. The two evaluation results show that the carrying capacity of agiculture water resouces in irrigation from 2006 to 2020 will become from weak levels gradually upgraded to middle level. To some extent, Thr carrying capacity of agiculture water resouces are able to maintain sustainable economic and social development of irrigation, but still need to increase the irrigation water resources development by the breadth of development turn to depth development, and should vigorously strengthen the construction of water-saving economic structure in irrigation aera.