Design On Diversion And Irrigation Projects For The Ecological Forestation In The Danan Moutain In Xining City

Green ecological protective screen construction area of the Danan Mountain is close to the urban district in the Xining city with ecological fragility and relative poor climate conditions, and this arid area lacks water which leads to the difficulty in the forestation. Although irrigation by power pumping in this area has achieved some results, not only power pumping consumes large power resources, but also construction scale is limited. In order to solve the water problem in the ecological construction, green ecological protective screen construction area of the Danan Mountain with the total area of 6.85 million hectares (shrubby net area of 2.884 million hectares) was selected in the ecological forestation and diversion and irrigation projects, and this area was in the range from the east of lime ditch to the west of Nan chuan river.Based on the objective of controlling and protecting ecological environment and the principle of water saving irrigation and optimal allocation of water resource, this study had carried out research on the planning of backbone ditch system projects including the first main canal and second main canal as well as the layout of supporting construction of 2.884 million hectares'irrigation pipe network. According to the domestic and overseas and local experience of water saving irrigation, geological survey and evaluation along with calculation of water supply and flow, combined with the local actual situation, and considering saving project investment, different programs were analyzed and compared, and finally the reasonable program of the canal and irrigation network system was determined, which provided basis for the decision of the project construction.Operation model of irrigation was determined in view of the human-oriented principle in the study; characteristics of each small watershed and administrative divisions were considered in the layout of the main canal, the branch canal and the lateral canal, providing good condition for making irrigation management institution; according to the current condition of the project area, comprehensive irrigation network system was established based on using for references and improving experience of the portable irrigation of Tailai county in Heilongjiang province and the selection of the model of fixed channel irrigation and portable irrigation.