| With the impact of climate change and human activities,the contradiction between supply and demand of water resources in Baojixia Irrigation Area has intensified,and the guarantee rate of agricultural irrigation in the irrigation area is low.Reservoir scheduling is an effective way to alleviate the contradiction between supply and demand of water resources and improve the efficiency of water resources utilization.Carrying out research on reservoir scheduling in Baojixia Irrigation Area provides theoretical support for the operation of reservoirs in the irrigation area,which has important scientific and practical significance.This paper takes the reservoir group in Baojixia Irrigation District,Shaanxi Province as the research object,constructs a multi-objective joint optimal scheduling model of the reservoir group in the irrigation area,optimizes the joint scheduling strategy of the reservoir group,and optimizes the reservoir scheduling map in the irrigation area,which effectively improves the agricultural irrigation guarantee rate in the irrigation area.The study draws the following main conclusions.(1)Analyze the runoff variation characteristics of Linjia Village of Weihe River.Based on the M-K test method and the Copula function method,the mutation point of the area rainfall sequence of the Linjiacun station control watershed,the runoff sequence of the Linjiacun station,and the precipitation-runoff dependency relationship was tested.The rainfall sequence before and after the mutation point conforms to the Gamma distribution,and there is no mutation.The sequence of the runoff from Linjiacun Station before the mutation point conforms to the Gamma distribution,and the sequence after the mutation point conforms to the LN distribution.The Clayton-Copula function is the best fitting result before the mutation point of the relationship,and the Gumbel-Copula function is the best fitting result after the mutation point.The precipitation-runoff correlation is poor after the abrupt point.(2)Estimation of water demand in Baojixia Irrigation Area.The Penman formula combined with the single-crop coefficient was used to calculate the irrigation water demand of the irrigation area according to the irrigation system of the irrigation area.The quota method was used to estimate the water demand for sufficient irrigation and the water demand for insufficient irrigation in the irrigation area.The improved Tennant method was used to calculate the ecological water demand.(3)Divide the hydrological year of Baojixia Irrigation Area by stages,and determine the flood-limited water level and the drought-limited water level of the Linjiacun Reservoir by stages.Fisher’s optimal segmentation method is used to divide the hydrological year period of Baojixia Irrigation District.The flood season is from May 11 to October 15,the main flood season is from July 1 to September 10,and the dry season is from November 16 to November 16.March 20.Combined with the Flood Control Manual of Baojixia Irrigation Area,the sliding water supply method was used to analyze the limited water level during flood season,single drought limit water level and staged drought limit water level in the irrigation area.The flood limit water level is 634.00m;the single drought limit water level is635.75 m from November to May of the following year;the staged drought limit water level is 633.50 m in November,629.91 m from December to the next March,and 629.91 m from April to May.634.72 m.(4)Construct a multi-objective canal-reservoir joint optimal scheduling model in the irrigation area.Generalize the topological relationship of reservoir groups in Baojixia Irrigation District,set up joint scheduling rules for reservoir groups,take the minimum water shortage rate in the irrigation area,the minimum number of super-deep damages to the water supply in the irrigation area,and the most equitable water supply in the area as the objective function,and consider the ecological water use in the river and other constraints.A multi-objective optimal scheduling model is constructed,and the NSGA-II-DE algorithm is used to solve the multi-objective model.The water supply reliability,water supply elasticity,vulnerability and water scarcity index are used as the risk assessment indicators for the reservoir water supply.For the non-inferior solution set,the multi-attribute SEABODE is used.The decision method selects the optimal solution.(5)Reservoir group scheduling strategy optimization and water supply risk analysis.Based on 3 kinds of water demand conditions,5 kinds of rules for filling reservoirs and canals,and 3 kinds of water level settings for different drought limits,a total of 45 different dispatching strategies have been formulated.Carry out a long series of dispatch research,optimize the optimal dispatch strategy under different water demand conditions,and optimize the dispatch map of the canal reservoir and the irrigation area reservoir.The results show that: the optimal water storage sequence is Wangjiaya Reservoir-Xinyigou Reservoir-Dabeigou Reservoir-Yanhe Reservoir-Yanhe Second Reservoir,and the optimal water supply sequence is Yanhe Second Reservoir-Yanghe Reservoir-Dabeigou Reservoir-Xinyigou Reservoir-Wangjiaya Reservoir;it is better to set the water level with dry water limit in stages under the condition of dry water demand,but not in non-dry years;compared with the current strategy,the optimization strategy not only improves the guarantee rate of the whole irrigation area,but also improves the guarantee rate of each irrigation area.The water supply guarantee rate of the district and the crop growth period have been improved;by analyzing the water supply risk evaluation indicators,theoretical irrigation conditions and under-sufficient irrigation conditions,optimal scheduling can comprehensively reduce the water supply risk in Baojixia Irrigation Area.Under sufficient irrigation conditions,Optimal scheduling can improve the reliability,vulnerability and water scarcity index of water supply in Baojixia Irrigation Area,but the elasticity of water supply is slightly reduced. |
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