Study On Optimal Operation Of Reservoirs In Baojixia Irrigation District

Climate change and high-intensity human activities have interfered with the normal hydrological cycle of the Weihe River Basin.The runoff has been variated and the runoff has been reduced,which has affected the sustainable development and utilization of water resources.In addition,the irrigation area lacks reasonable rules for the joint operation of reservoirs,the contradiction of water use in the irrigation area is prominent,the annual guarantee rate of irrigation is low,and the ecological water use of the river is destroyed.Therefore,carrying out research on reservoir scheduling in irrigation districts is of great significance to alleviating the contradictions in water use in irrigation districts and guiding the operation of irrigation districts.This paper takes the Baojixia irrigation district reservoir and hydropower station system as the research object,constructs the Linjiacun Reservoir multi-objective optimization scheduling model,discusses the reservoir multi-objective competition mechanism;according to the drafted Linjiacun Reservoir and the irrigation area polymerization reservoir joint water supply rules,constructs the irrigation area reservoir joint operation model,verify the rationality of its rules,and obtain the corresponding reservoir scheduling diagram,aiming to provide theoretical support for the scientific management and operation of the irrigation area.The main research conclusions of this paper are as follows:(1)The sliding entropy theory method for diagnosing the variation points of runoff sequence is constructed.The sliding window technology is combined with approximate entropy,sample entropy,two-dimensional entropy,and fuzzy entropy,and the sliding entropy is used to obtain the runoff entropy curve of Linjiacun Station and Weijiabu Station over time.Through analysis of its dynamic structure characteristics,it is found the runoff at Linjiacun Station had abrupt changes in 1971 and 1993;the runoff sequence at Weijiabu Station had abrupt changes in 1968 and 1993.The sliding t test and Brown-Forsythe test verify the reliability of the above-mentioned variation point results.(2)Based on the planting data and meteorological data of the irrigation area from 1987 to 2017,the monthly irrigation water demand of the irrigation area is calculated by the method of referring to the crop water demand;using the Tennant method and the 90%guarantee rate of the dryest monthly average flow method to calculate the Linjiacun ecological base flow process of the section.(3)A multi-objective dispatching model of Linjiacun Reservoir at the head of the canal was constructed.Based on the water supply target of Linjiacun Reservoir,a multi-objective scheduling model of irrigation-power generation-ecology was established,and the solution was solved by using the NSGA-II algorithm.The scheduling non-inferior solution set of the abundant,flat,and dry years was obtained.It was found that: the pareto of each typical year front is basically distributed on a relatively smooth spatial surface,and the competition and game relationship between the targets is good.The pareto scatter diagram is two-dimensionally projected,and the competitive relationship between the two scheduling targets is analyzed,and it is concluded that for the wet year and the flat water year,when the amount of ecological overflow and water shortage is constant,the irrigation benefit will show up as the power generation benefit increases.Declining trend;when the power generation benefit is constant,the amount of ecological overflow and water shortage will increase with the increase of the irrigation benefit.For dry years,with the increase of irrigation benefits,the amount of ecological overflow and shortage of water will decrease,and the benefit of power generation will increase first and then decrease;when the irrigation benefit is constant,the competition between the benefits of power generation and the amount of ecological overflow and shortage The relationship is strengthened,that is,as the benefit of power generation increases,the value of ecological overflow and water shortage also increases.(4)A joint optimal dispatch model of "two reservoirs-two power stations" in the irrigation area was constructed.Taking the complex reservoir and hydropower station system in the irrigation area as the research object,the five canals and reservoirs combined with reservoirs in the irrigation area are aggregated,and the joint water supply rules of Linjiacun Reservoir and Aggregation Reservoir are drawn up,and the joint dispatch model of "two reservoirs-two power stations" is established.Solve and evaluate the risk of reservoir water supply dispatching,and compare the optimized results with the conventional dispatching results.The results show that the dispatching rules formulated in this article are reasonable.Using the dispatching method in this article can reduce the average annual irrigation water shortage in the irrigation area from 36.74 million m3 to 33.55 million m3,and increase the annual irrigation guarantee rate from 56.67% to 66.67%.The power generation of the system increased by about 1 million k Wh;the risk assessment results of the reservoir water supply showed that the reliability,resilience,vulnerability and other risk indicators of the optimal dispatch were better than those of the conventional dispatch.Comprehensive analysis shows that the joint scheduling rules formulated in this paper are better than conventional scheduling rules.