Study On Hydrodynamic Characteristics And Water Quality Variation Of Urban Artificial Lake

As part of the development of modern cities,urban artificial lakes not only provide a comfortable and stable ecological environment for people in cities,but also have the function of regulating and improving urban hydrology.From the analysis of hydrodynamic characteristics of urban artificial lakes,lakes have small flow speeds,lack of supply water,generally long replacement times and are not conducive to dilution and diffusion of pollutants;secondly,artificial lakes are located in areas where human activities are concentrated and the pollution caused by human activities,It is often larger than the self-purification capability of the water body,so the water quality of the artificial lake is polluted and the ecological damage is more pronounced.In order to improve the water environment of urban artificial lakes and create a beautiful urban ecological environment,this study takes Yanming Lake,as an example to first analyze the current status of lake water environment and changes in water quality,and then analyzes the law of lake water dynamics and analyzes sandy changes.The effect of water recharge on water qualityand finally the research on the regulation and control of improving the water environment,the research results can provide reference for the improvement and management of the water environment of artificial lakes in northern cities.It mainly includes the following research work:(1)Based on the water quality data during the monitoring period,the annual trends of DO,water temperature,pH,COD,TN,TP and chl-a were analyzed.Between ??? types of water.Through the fuzzy comprehensive evaluation,the water quality of Yanming Lake is generally maintained between class ???.The worst water quality in autumn is class ? water.Compared with previous water quality assessment results,the water quality gradually deteriorates;Using the comprehensive nutrition state index is between the middle and the eutrophic in Yanming Lake.The analysis of the ratio N/P of 8?25 in the lake is the alternating type of restrictive nutrient N and P,which makes it more difficult to improve the lake water quality.(2)Based on the two-dimensional hydrodynamic model combined with the sediment module,the effects of different wind fields,through-putting flow,sediment concentration and water level changes on the hydrodynamics of the lake were quantitatively studied.The study shows that the wind plays a leading role in the change of the lake flow field,in which the wind speed is the main factor affecting the lake flow velocity,and the wind direction plays a leading role in the direction of the lake circulation.The throughput flow has a great influence on the velocity of the water at the lake,the flow rate is minimum when the water flow is 0.4m3/s.Sandy water supply affects lake water dynamics mainly by changing the structure of water flow.The influence of sediment concentration on the velocity of water at the inlet of lakes is significant,the logarithmic growth relationship(R2=0.952),the effect of sediment concentration on hydrodynamics and the flow of supplement water closely related.The water level is one of the factors affecting the hydrodynamics of lakes.There are differences in the flow rates of different water levels and water levels and lake speeds.Maintaining the ecological landscape water level,when the water level is appropriately increased and decreased and the throughput flow is increased at 0.3m3/s also the sediment concentration is less than 1kg/m3,which is beneficial to the improvement of lake hydrodynamics.(3)Couple the water quality model based on the hydrodynamic model and the sediment module,analyze the impact on the main water quality indicators in the process of sediment supply and improve the study of water environment regulation.For many water quality model parameters,sensitivity analysis was used to verify the main parameters indicating that the model can reflect the hydrodynamic water quality and sediment migration transformation of Yanming Lake.Sandy water supply is beneficial to the purification of lake water quality.The adsorption and desorption of sediment is the process of distribution or redistribution of pollutants in the two phases of water and sediment,and the distribution effect of sediment on different water quality indexes is different.According to the water volume and water quality conditions of different replenishment control measures with constant runoff into the lake and different fluctuating flows will be adopted the Chanhe.If the water quality meets ? class the run off of the supplemental water can be appropriately increased to 0.3 m3/s and the water quality can reach IV class.The following can be separated by water supply the maximum interval can be one month.