Research On Hydrodynamic Optimization Scheme Based On Water Quality Improvement

With the impact of climate change and human activities,the problems of water shortage and water environment deterioration have become increasingly prominent,regional ecological water replenishment has become an important measure to alleviate the shortage of water resources and the deterioration of water environment.The water body has a certain self-purification ability,and hydrodynamics is one of the key factors restricting the efficiency of water purification.At this stage,Baiyangdian Lake is under the dual pressure of insufficient hydrodynamic power and deterioration of water quality.How to improve the insufficient hydrodynamic power of the Dian District and at the same time alleviate the deterioration of water quality is an important issue in Baiyangdian’s ecological improvement.In this paper,through the establishment of hydrodynamic and water quality coupling relationship experiments,based on the law of hydrodynamic water quality response,the MIKE21 model is used to study the hydrodynamic optimization scheme.The main research contents and results are as follows:(1)The Baiyangdian MIKE21 hydrodynamic numerical model was established,the calibration and verification of the model were completed,and the accuracy of the model was ensured.Based on the simulation results,the current situation of Baiyangdian hydrodynamics and the influence of rivers entering the Baiyangdian on hydrodynamics of the Dian District are analyzed.The results show that Baiyangdian hydrodynamics has natural shortcomings at this stage,which is affected by both internal topography and water shortage.The influence of the rivers entering the Dian District on the hydrodynamics of the Dian District is mainly concentrated in the main channel,and the effect of improving the hydrodynamics under low flow is limited.(2)An experimental study on the coupling relationship between hydrodynamics and water quality was carried out,and the response law between hydrodynamics and water quality was analyzed.By selecting the experimental area inside Baiyangdian Lake,combined with the water circulation device,a reasonable hydrodynamic water quality observation experiment was set up.Based on the experimental monitoring data,the MIKE21 hydrodynamic model of the experimental area was established.Based on the simulation results,the hydrodynamic promotion benefit of the water circulation device was analyzed.At the same time,the hydrodynamic and water quality data were analyzed in combination with the water quality data.The results show that the content of DO and TN in the water body fluctuates greatly during the process of increasing the flow rate,and the response to hydrodynamic changes is more sensitive,showing a good correlation with the flow rate.The increase in hydrodynamic power is beneficial to increase the self-purification ability of the water body.The result can provide a certain reference value for the improvement of water quality.(3)On the basis of comprehensive consideration of the ecological dredging project in Dian District and the demand for water resources protection in Dian District,combining the three major water replenishment channels of the upstream reservoir,the Yellow River Diversion Project to Hebei and the Middle Route Project of the Southto-North Water Diversion Project,while referring to historical water replenishment data,consider the actual water replenishment.Feasibility,set up a terrain creation plan and an optimization plan for water supplement.(4)The MIKE21 model was used to simulate the hydrodynamic optimization schemes,and the hydrodynamic optimization effects were compared and analyzed based on the simulation results.The simulation results show that the terrain construction plan will only form slight fluctuations in the area flow rate within the dredging range,and the optimization efficiency is low.The water replenishment program can improve the hydrodynamics of the Dian District within a certain range due to the promotion of energy to the water body.Among them,Option 5 is the best for the hydrodynamic improvement of Dian District,and the optimization area is the widest,which can better increase the vitality of the water body and improve the water purification efficiency.