Study On Optimal Allocation Of High Standard Basic Farmland Irrigation Water Under Water Resources Constraints

China's water and soil resources are increasingly constrained and food security is threatened.As a major grain producing province in Henan Province,in the new situation,in order to ensure the realization of the strategic goal of grain production and ensure national food security,it is necessary to optimize the allocation of irrigation water for farmland,strengthen the construction of high-standard farmland,and improve the utilization rate and output rate of cultivated land.The bottleneck of water resources restricts the development of agricultural production.This paper takes Xinzheng City as the project area to study the optimal allocation of high standard farmland irrigation water under the constraints of water resources.Xinzheng City is located in the central part of Henan Province.It is a semi-arid and semi-humid continental climate.The precipitation is unevenly distributed during the year.The groundwater level is greatly affected by precipitation factors.The water level rises during the wet season,and the water level decreases during the dry season.The total amount of resources is generally difficult to meet the needs of irrigation water for farmland.Therefore,depending on the degree of impact of crop water deficit on yield at different growth stages,the limited amount of irrigation water is used in the most critical water demand stage of crops,so-called Fill the "key water."Under the premise of evaluating the water resources endowment conditions of Xinzheng City and the balance of supply and demand of regional water resources,it is concluded that the farmland irrigation water source is insufficient,and a reasonable and feasible crop irrigation system should be formulated under the constraints of water resources during the whole cropping period.Internally allocate a limited amount of water,and optimize the allocation of irrigation time and irrigation quota to minimize the loss of production caused by water shortage to obtain the best production target.The main research results are as follows:(1)The availability of water resources in Xinzheng City is far from meeting the demand for irrigation water for farmland.Under the condition that the surface runoff in the farmland area is fully accumulated and utilized,the total amount of water resources available is still difficult to meet the needs of irrigation water for the farmland,but some The area is basically close to the balance of supply and demand.(2)Because the water requirement for winter wheat irrigation in Xinzheng City is 1099-1469m3/hm2,the water requirement for summer maize irrigation is 1035-1324m3/hm2,and the annual water requirement for winter wheat-corn standard planting system is 2134-2793m3/hm2,which is much smaller than "Henan Province Water Quota",self-produced water can not meet the needs of adequate irrigation and irrigation quotas,so it is necessary to formulate a system of inadequate irrigation.(3)Based on the constraints of water resources,formulate irrigation quotas that match the amount of water resources available,and according to the impact of crop water deficit on yield at different growth stages,the effective wet layer depth at the same growth stage of crops,and the appropriate soil water content.Rate,develop a district water-saving irrigation system,and prioritize limited water sources for crop growth critical periods and critical water demand stages.(4)The high-standard farmland construction of different types of district water resources(available modulus)as the basis for determining the irrigation quota,according to the results of irrigation quota analysis and crop water production function research results,the high-standard farmland in Xinzheng City is divided into Dry farming areas,non-sufficient irrigation areas,and fully irrigated areas are classified into three primary types,and on this basis,they are subdivided into seven secondary types.(5)Based on the suitability and restraint of the natural environment endowment conditions in different types of areas,adopting the technical idea of "based on the partition,the target is set by resources,and the target is fixed",and the water is determined according to the characteristics of different types of areas.Resource endowment conditions establish the appropriate number of irrigation times and time,as well as matching farmland irrigation targets and irrigation project configuration patterns.