| With the increasing demand of human beings for water resources and the severe shortage of water resources,food security is facing challenges.China has a large amount of water resources,but its per capita occupancy is small.The distribution of water resources is uneven in time and space.Water resources that can be used directly are quite limited,and water shortages are serious.As a result,many crises in the climate,energy,food,and financial markets are created.Affect the development of countries and regions.In recent years,the country has made a series of major decisions on"implementing food strategic projects and accelerating the establishment of grain core areas."The comprehensive reform plan of modern agriculture in the"two plains"of Heilongjiang Province further pointed out the direction for building modern agriculture and developing grain production in Heilongjiang Province.Irrigation area is an important food production area.Heilongjiang Province is also the country's largest food production base.It studies the allocation of water resources and the potential for water saving in agriculture in the irrigated areas of Heilongjiang Province.It meets the requirements for the construction of commodity grain bases and grain production in Heilongjiang Province,raises the income of farmers,and coordinates the Songhua.It is of great significance for the river basin to rationally allocate and utilize water resources,increase the efficiency of water resources utilization,and achieve both the economic benefits and the rational development of water resources.This paper takes the Jinxi Irrigation District in Fujin City of Heilongjiang Province as the research object.Based on the analysis and prediction of the supply and demand water balance in the study area,the water resources carrying status of the irrigation area is analyzed.Based on this,a water resources allocation optimization model for irrigation districts combined with linear fractional planning,two-stage stochastic programming,and stochastic-constrained planning is constructed,and the limited surface and underground water supply capacity is efficiently allocated to the various water departments in each sub-region(Agriculture,Industry,life,and ecology,and optimize the allocation of water resources throughout the growing period for typical agricultural crops.Based on the results of water demand forecasting and the optimal allocation of water resources in the irrigation area,the water saving potential of agriculture in the area was analyzed and the mode of water saving was discussed.The research content and response results of this paper can provide technical and program reference for the efficient use of water resources in large-scale irrigation areas in Heilongjiang Province,so as to alleviate the contradiction between supply and demand of water resources in irrigation areas.The main research contents and conclusions are as follows:(1)Based on the characteristics of multiple water sources in Jinxi irrigation area,this paper analyzes the dynamic characteristics of surface runoff and groundwater,analyzes the available water and water requirements for surface water and groundwater,and analyzes the supply and demand balance between surface water and groundwater.In 2030,the total water requirement of the Jinxi Irrigation District is 549.59 million m~3,the water supply capacity is 522.69 million m~3,and the water shortage is 26.9 million m~3.The four sub-regions are all in water shortage.The status of agricultural water resources in each subarea of the irrigated area is under the condition that groundwater is seriously overloaded,which affects the balance of supply of agricultural water resources in the irrigated area,and also causes unfavorable conditions for crop irrigation.The water resources carrying status of industry and living can meet the development of irrigation districts,but it is still necessary to further develop water-saving measures.The lack of water in the irrigation area directly leads to the reduction of crop yield,the economic benefits cannot be effectively exerted,and the long-term development of the irrigation area is affected.This fully explains the necessity of optimizing the water resources allocation in the Jinxi irrigation area.(2)With the aim of maximizing the efficiency of allocation,a water resource allocation model for irrigation districts was established by combining linear fractional planning,two-stage stochastic programming,and stochastic-constrained planning to optimize the allocation of water resources in different districts and different water departments.Effectively improve the efficiency of water allocation and can handle the uncertainty in the configuration system.On this basis,the output of the optimized allocation of water resources in the irrigation area was used as the right-side item of the water supply constraints for the optimal allocation of the model's water resources in the irrigation area,and water resources were optimally allocated to the entire crop growth period in the irrigation area.The results show that the amount of available water increases with the increase of risk probability of violation,and the probability of illegal risk is high.The amount of available water allocated to each subarea of the irrigation district will be more;the amount of water distribution at different flow levels will follow the risk of violations.The probability increases and increases;when the probability of risk violation is the same,the amount of water distribution in the irrigation area decreases with the decrease of the incoming water flow,and the greater the risk probability of violation,the smaller the reduction in the decrease of the flow rate;the risk of different violations Under probabilistic conditions,the water shortage increases with the decrease of the flow rate,and the probability of system violation risk reaches the maximum,but water shortage still occurs.The economic benefits of the irrigated areas are increasing with the increase of the risk probability of violations,and the maximum point of growth rate of economic benefits is reached at q=0.15.Therefore,the water distribution volume of surface water and groundwater in the irrigated area is selected when the risk probability of violation is q=0.15 as the recommended optimization configuration scheme.In the optimized water allocation for crops,the total amount of water at high,medium,and low flow rates was 334.89 million m~3,304.669 million m~3,and 220.16 million m~3,respectively.At the three flow rates,the proportion of rice irrigation in Jinxi Irrigation District was79.62%,82.08%,and 80.37%.The irrigation rate of rice at different flow rates was stable.The research results can provide the basis for the decision-makers of the irrigation area to allocate water according to the actual water level in the irrigation area and ensure the operation of the irrigation area,and also provide research directions for water saving in the irrigation area.(3)Analyze irrigation water potential in agriculture.Analyzing the existing methods for calculating water-saving potential,based on planning the annual water supply scope and food demand of Jinxi irrigation area,the method for calculating the water-saving potential of agricultural water use in the Jinxi irrigation area was studied.The results show that the water-saving potential of the districts in Jinxi Irrigation Area is relatively large.The larger the irrigated area,the greater the water-saving potential.The higher degree of surface water utilization along the Songhua River,and the abundant subarea of groundwater recharge,The potential for water conservation is also relatively large,and the development of water-saving potential is relatively low for subdistricts dominated by long-distance channel diversion and groundwater irrigation.The water-saving potential of rice is far greater than the water-saving potential of soybean and corn.The water-saving potential of agriculture based on the water allocation after optimal allocation of water resources in Chapter 4 is significantly lower than the agricultural water-saving potential calculated based on the annual agricultural water consumption forecast in the third chapter,and the water consumption after optimized allocation not only can satisfy crops.The need for growth also saves water for agriculture.The results further illustrate the feasibility and rationality of the optimal allocation of water resources in this study,and can also promote the development of water-saving technical measures in irrigation areas. |
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