Optimization For The Irrigation System Of Rice And Vegetable Rotation In The Eastern Coastal Areas

Shortage of water resources to make China’s food security problem becomes more serious, has become a key problem restricting sustainable development of our social economy and agricultural. The coastal area where affected by geographical location, population density and industrial development, the contradiction between supply and demand of water resources is particularly prominent. The coastal area is covered by sandy soil, which is very suitable for the growth of the rain fed crops such as vegetables. But with the long-term cultivation of the rain fed crops, the soil secondary salinization phenomenon and continuous cropping obstacle of crops have intensified, taking rice and vegetable rotation cropping pattern is an effective way to alleviate such problems in coastal areas, which has an important positive significance in guaranteeing the food security and ensuring the sustainable development of Agriculture. Due to the different water requirement characteristics of rice and vegetables, in view of the rice and vegetable rotation cropping pattern at coastal area, to carry out at the appropriate cropping patterns to optimize irrigation systems have very important significance.This paper summarizes the development of irrigation system of pipeline and the optimization of pipeline network in domestic and foreign. Based on the results, and combined with the existing situation and different irrigation characteristics of rice and vegetable rotation cropping patterns in coastal areas, mainly carried on the following research:Firstly, comparison and selection of the low pressure pipeline irrigation as a suitable irrigation project form of the rice and vegetable rotation cropping pattern. According to the different water requirement characteristics of rice and vegetable rotation, the suitability evaluation index to establish the form of irrigation, compared the suitability analysis of canal irrigation and low-pressure pipeline irrigation, choose the irrigation system of low-pressure pipeline as the best irrigation method which adapted to the regions of rice and vegetable rotationSecondly, optimizing the system of low pressure pipeline irrigation. Pipeline network system optimization is reflected in the choice of network arrangement, and puts forward the methods for selection of round pipe layout group division, and verify the reliability of the method; Water diversion project optimization is reflected in pump matching selection, analyzed the advantages of comparison between two parallel pumps and single pump operation; Finally based on the pipeline network arrangement and the preferably selection of matching pumps, combined with the existing pipe diameter optimization model results, with the lowest annual cost to the pipeline network as the target, optimizing the pipe diameter of pipeline network by boundary flow method.At last, combined with typical cases for optimization analysis. Selected a certain agricultural project in coastal area of Jiangsu province, applied the above optimization method to the project. Through the comparison with low pressure pipe irrigation pipe of conventional design method, that has obvious superiority in terms of network investment, and can completely meet the irrigation water demand of rice and vegetable. Verified the good effect of low-pressure pipe irrigation system optimization which is applied to rice and vegetable rotation Pattern. Finally, carried out a statistical analysis on the low-pressure pipeline irrigation of coastal area in Jiangsu province, by analyzing the relationship between function control area and the annual cost of the low-pressure pipe irrigation system, determined that the appropriate control area is about 25～35hm2.