Water Quality And Quantity Coupling Simulation Of Guangfu River Wetland Group Research On Control Scheme

The East Route Project of South-to-North Water Diversion is a long-distance comprehensive water diversion project which can alleviate the contradiction between supply and demand of water resources in North China and support the sustainable development of national economy and society in the region.Water conveyance safety has been a hot issue since construction.Nansi Lake is one of the two regulating and storing lakes in the Shandong section of the eastern line.Guangfu River is one of the important tributaries entering the lake,and its entrance is close to the water transmission line-Liangji Canal.Therefore,the water quality safety of Guangfu River is very important.In order to ensure the water quality safety of Shandong section water conveyance project,Shandong provincial government has built a sewage interception diversion project.The main task of pollution interception and diversion project in Jining City is to intercept and store urban reclaimed water,ensure that the water quality of Guangfu River into the lake reaches III water quality standards,and ensure the water quality safety of Nansi Lake.Guangfu River wetland group is the key to ensure the water quality of Guangfu River into the lake in pollution interception and diversion project.With the rapid development of economy,the discharge of reclaimed water exceeds the original design water quantity.The water level of the upper reaches of the Liaogou River control sluice is rising and the sluice top is flat.The water quality of Nansi Lake is at risk.It is necessary to determine the water quality and water quantity control scheme to ensure the safety of Nansi Lake.Therefore,this paper takes Guangfu River wetland group as the research object,and uses MIKE software to establish the water quality and water quantity coupling simulation model of wetland group.Based on the analysis of reclaimed water supply and demand,the water quality and water quantity regulation scheme of wetland group is proposed and optimized by simulation.The main research contents and results are as follows:(1)Construction of water quality and quantity coupling simulation model of wetland groupBased on the monitoring data of topography,hydrology and water quality in the study area,the MIKE software was used to establish the one-dimensional water quality and water quantity coupling simulation model of the water conveyance canal,and the two-dimensional water quality and water quantity coupling simulation models of the Guangfu River constructed wetland and the constructed wetland in the water storage area were established respectively.The standard connection method in MIKE FLOOD is selected to establish the connection between the outlet endpoint of one-dimensional model and the grid unit at the inlet of two-dimensional model.The output results of one-dimensional model are set as the boundary conditions of the inlet of two-dimensional model,and the water quality and water quantity coupling simulation model of wetland group is constructed.Using the measured data from January 1,2020 to January 7,2020 and from January 8,2020 to April 1,2020,the model is calibrated and verified respectively.Parameter setting and model construction are reasonable,the error range is less than 20%,within the allowable range.(2)Simulation and optimization of water quality and quantity control scheme for wetlandsIn view of the existing water environment problems in the study area,three water quality and quantity control schemes are determined by comprehensively analyzing the water demand of reclaimed water and wetland in the water storage area with the goal of reducing the upstream water level of the control sluice of the Liaogou River.The established water quality and quantity coupling simulation model of wetland group was used to simulate and analyze different regulation schemes.Based on the results of simulation analysis,Scheme 1 is proposed as the optimal scheme:Reclaimed water of 10000 m3/d is taken as industrial water at the outlet of the water storage area,and 63000 m3/d is taken as supplementary ecological water for Guangfu River.After regulation,the average concentrations of COD and ammonia nitrogen at the outlet of Guangfu River wetland decreased from 15.19 mg/L and 0.42 mg/L to 14.58 mg/Land 0.40 mg/L,respectively.The average concentrations of COD and ammonia nitrogen at the outlet of constructed wetland decreased from 14.05 mg/L and 0.54 mg/L to 12.19 mg/L and 0.52 mg/L,respectively.The water quality of the wetland group is in good condition and meets the III water quality standard.(3)Optimization of optimal control scheme of water quality and quantity in wetlandsIn order to improve the utilization efficiency of water resources,under the premise of meeting the requirements of water quality standards,it is considered to increase the utilization of recycled water in wetland groups.Based on the supply and demand analysis of reclaimed water emission and reclaimed water utilization,the optimized scheme 1 was further optimized.Based on the original scheme,the amount of water transferred from the constructed wetland in the water storage area to supplement the ecological water of Guangfu River increased to 100000 m3/d.After optimization,the average concentrations of COD and ammonia nitrogen at the outlet of Guangfu River wetland decreased from 14.58 mg/L and 0.40 mg/L to 10.92 mg/L and 0.33 mg/L,respectively.The average concentrations of COD and ammonia nitrogen at the outlet of water storage area wetland decreased from 12.19 mg/L and 0.52 mg/L to 9.7 mg/L and 0.325 mg/L,respectively.Compared with the current situation,the average concentrations of COD and ammonia nitrogen decreased by 28.11%and 21.43%at the export of Guangfu River constructed wetland,and decreased by 30.96%and 39.81%at the export of constructed wetland in the water storage area.The optimized regulation scheme increases the water exchange of the wetland and improves the purification ability of the wetland.While ensuring the water quality of the Guangfu River outlet reaches the standard,it not only provides an effective utilization way of reclaimed water,but also recovers the river function of the corresponding section of the Guangfu River.