The Study On Water-Saving Irrigation Zoning And Engineering Optimal Design In Xinjiang

The 21st century is the time when social economy has a rapid development in China. It is also the time when the conflict between water resources supply and demand becomes unprecedentedly serious. As the population booms, increasing of food demand and development of industrialization and urbanization, water shortage has greatly prevented agriculture and even national economy from continuous development. So that developing water-saving irrigation has become an important task of solving water shortage problems. In order to direct water-saving irrigation more successfully, it is necessary to do some macroscopic research on the scope, type, potential and benefit of the water-saving development, inorder to make reasonable planning for water-saving agriculture. In this paper, a study was carried on water-saving irrigation zoning, and engineering optimal design based on existing methods and experiments. Major results are as follow.1.A series of zoning indexes are presented by considering the Xinjiang characteristics, and data collected locally. Through statistic analysis and treatment, an appropriate group of indexes were suggested. The group of index is adapted to Xinjiang region and fit to agricultural water-saving zoning. Moreover, different weighing coefficients were given as variable index.2.Comparisons were made among different methods and approaches of zoning by introducing cophenetic correlation coefficient. The result shows that fuzzy clustering method is better than system clustering method, and Euclid distant method is better than other counterparts.3.The value of reference crop evapotranspiration is need when calculating the index of water deficient degree, so different methods of calculating ET0 were analyzed and compared, and then results were drawn. Under the same climatic condition, the 1948Penman method is better than FAO-24 Penman and FAO-24 Radiation for all climatic areas of Xinjiang. If climatic data are insufficient, the Hargreaves method for arid area and Priestley-Taylor for humid may provide reliable ET0 estimates. Meanwhile, the relationship between the ET0 values computed by Penman-Monteith method and pan evaporation method was analyzed, this can provide a reference for estimating ET0 using evaporation data for Xinjiang region.4. By analyzing engineering task and planning principle, several optimization models varying in objective functions were created and different results are generated respectively. By comparising these results, the suggested program is the model based on multiple objective functions of least investment and most benefit. For its four ideal economic indexes, higher benefit-cost ratio and per unit water efficiency, and the investment is 0.3 billion yuan lower than conventional planning.5. Taking Changji state for instance, the engineering cost decreases as agricultural total or subsurface water increase by sensitivity analysis of water change on cost. As the total water ncreases 1%, engineering cost decreases 3.13%. The condition of subsurface water the project nvestment decreases by 4%. This means that engineering cost is more sensitive to subsurface water.