Study On Optimal Allocation Of Water Resources In Ningxia Yellow River Irrigation Area

With the rapid development of social economy, the demand for water resources in Ningxia Yellow River irrigation area is increasing, and the contradiction between supply and demand became increasingly prominent. As a result, shortage of water resources has become an important factor restricting the economy development of Yellow River irrigation area. Total water resources in Ningxia Yellow River irrigation area is6.5billion m3. Ninty percent of the water are used for agricultural purposes, of which only40%are used for irrigation. So the water for agriculture purposes enjoys high proportion as well as low utilization efficiency. Facing the coexisting of water scarcity and low utilization efficiency, a combination of simulation and optimization methods for the optimization of water resources in Yellow River irrigation area is studied in this paper. Based on some advanced technologies like GIS and RS, this study, taking Ningxia Yellow River irrigation area as the experimental area, constructs a suitable SWAT model for the irrigation areas, and applies the model to the irrigation water management. On the basis of investigation on water resources condition and present development of Ningxia Yellow River irrigation area, this paper establishes an optimal allocation model of regional water resources for sustainable development. This model takes the maximum comprehensive benefits of society, economy and environment as the target. PSO (Particle Swarm Optimization) algorithm is applied to solve the model, and gets the optimal allocation of water resources in each planning level years under different precipitation frequency. The major results are as follows:(1) An investigation on natural geographical situation, social economic condition and the present water resources development of Ningxia Yellow River irrigation area is conducted to find out the main problems in the process of water resources development and utilization in the area.(2) A distributed hydrological model is developed for Yellow River irrigation area based on the SWAT model (Soil and Water Assessment Tool). The hydrology, weather and water use information from1990to2012of the irrigation area are used to simulate, the sensitive parameters were estimated. The simulation results are estimated by RE, R2and Ens, the calibration for monthly flow and sediment data are performed from2000to2006, the model is further validated with the monthly flow and sediment data of2007-2011, which attained excellent results. The simulated results of two monitoring points meet the estimated requirements, and SWAT model is applicable to the Yellow River irrigation district flow and sediment simulation.(3) The SWAT model is employed to analyze the potential change of runoff on the coditions of climate change and land use change of Ningxia Yellow River irrigation area. The result shows that the changes in temperature and precipitation impact on runoff. And the sequence of runoff yield for different land use types in the area is:cultivated land> forest land> grassland.(4) Taking2009as the present situation level year, the planning level years2015and2025of Ningxia Yellow River irrigation area economic social development is predicted considering the water-saving measures. Quota prediction method is used to predict the water requirements of agriculture, industry, and ecological in Yellow River irrigation area of different planning level years. With the established SWAT model for Yellow River irrigation area, the research predicts the amount of runoff to predict the supply amount of different planning level years. Furthermore, it analyzes the balance of water supply and demand in different planning level year of Yellow River irrigation area of analysis.(5) According to the theory and principle of optimal allocation of water resources, a multi-objective optimal allocation model of regional water resources is established based on theory of sustainable development and the parameters of the model is determined. This model takes the maximum comprehensive benefits of society, economy and environment as the target. The improved PSO (Particle Swarm Optimization) algorithm is used to solve the model; the model gets different optimal allocation results for50%,75%and95%of2015and2025. Countermeasures and suggestions of reasonable exploitation and utilization of local water resources are proposed based on the analysis to the allocation results.