Simulation Research On Water Quality Assurance Of Urban Small And Micro Landscape Water Bodies

Urban small and micro landscape water often suffer from closed watersheds,poor mobility,and deteriorating water quality.It is an urgent problem to improve the water environment of this type of water and promote the water environment quality.Artificial water supply or water circulation is one of the ways to improve the hydrodynamics of water bodies,it is necessary to reduce pollutants by technical measures can ensure the rationality of the water environment capacity.Analyzing the current status of water environment through long-term monitoring of research objects,and a water environment model was established on hydrographic topography data to study the change law of water quality under different environmental factors.The water quality has been explored under different artificial water replenishment positions,circulation flows and reduction targets to provide important practical significance for comprehensive environmental management of landscape water environment.The monitoring data of an artificial lake in Hengshui City for 10 months shows that the water quality first rises and then declines with seasonal changes,and rainfall evaporation plays an important role in water quality.COD was higher than 40mg/L from June to August,TN concentration was generally higher than 2mg/L,TP concentration was relatively low,and the comprehensive nutrient index showed severe eutrophication in summer.The environmental factors under the model simulation affect the water quality changes.The temperature below 24°C is conducive to the removal of nitrogen and phosphorus.Higher light intensity(>800Lux)is conducive to the self-purification of the water body.The three parameter conditions have a strong correlation with the contents of TN and TP in the study area,while dissolved oxygen and wind speed have little effect on the contents of TN and TP in the study area.Propose pollutant reduction targets based on the influence of environmental factors.The location and number of water diversion outlets affect the spatial distribution of water dynamics and quality.Away from water suppy part,higher water depth and bigger area showed lower flow rate.The water quality shows that better water quality basic on the closer to the replenishment outlet.In addition,the hydrodynamic distribution of the water body is greatly affected by the regional area and water depth.The smaller the area and the shallower the water depth,the stronger the water body fluidity.Water diversion increases water flow while diluting the concentration of pollutants in the water body and improves water quality.The water quality was improved under different flow cycles,and the best results were shown when the cycle flow was 0.4m3/s and 0.6m3/s.The water quality of Class V can be reduced to the surface water quality standard of Class IV under the water circulation within 30 days.The water circulation has limited hydrodynamic improvement in areas with large area and large water depth,and water velocity is affected by the location of water,bottom roughness and artificial lake shape.The water self-purification ability has been improved becasued of the water circulation improved the hydrodynamic force of water.The water quality conditions of working conditions(WC)under different pollution reduction targets are: WC1(Q: 0.2 m3/s,not cut)< WC2(Q: 0.4 m3/s,not cut)< WC3(Q: 0.6 m3/s,not cut)< WC4(Q : 0.2m3/s,reduced by 20%)< WC5(Q : 0.4m3/s,reduced by 20%)< WC6(Q : 0.6m3/s,reduced by 20%)< WC7(Q : 0.2m3/s,reduced by 40%)< WC8(Q : 0.4m3/s,reduced by 40%)< WC9(Q : 0.6m3/s,reduced by 40%),among which WC 3,6 and 9 have the best pollutant removal effect under the same circulation flow.The concentration of pollutants in the water area decreases with the increase of the reduction degree under the same pollutant reduction target,but the effect on the removal rate of pollutants is small.Through the simulation analysis,the best scheme of hydrodynamic water quality improvement is obtained,which provides new ideas for the selection of water environment improvement strategies for urban landscape water bodies.