Research On Water Quality Model And Preservation Scheme Of The Urban Landscape Water

Due to the urban landscape water has low velocity and its self-purification capacity is weak,the water is easy to be deteriorated and contributing to eutrophication.So the water quality model,as an important tool for researching the rules of migration and transformation of pollutants in the water,plays a vital role in researching on the change of water quality in landscape water.Firstly,we took the landscape water in Tianjin airport economic zone as our research object and monitored the water on the basis of prophase investigation and the layout of monitoring points.Then we analyzed the water quality and evaluated the eutrophication of the landscape water based on the results of monitoring,and we found that the index of water quality such as COD,total phosphorus can not meet the standard V and the landscape water was in moderate and severe state of eutrophication.Secondly,according to the data of meteorology and hydrology,we built the WASP model of the landscape water in airport economic zone,and simulated the change of COD,ammonia nitrogen,total phosphorus,dissolved oxygen and chlorophyll-a.The model had a good performance in reflecting the actual changes of the pollutants.Also,we tested and analysed the validity of the model by using the relative error,and could find the results of model were satisfactory.Then,we studied the WASP model of the landscape water in airport economic zone from uncertainty theory:(1)For the uncertainty of the input values,we added random error term to the pollutants concentration to study the influence of the uncertainty changes of the input values,and we used the Root Mean Square Error(RMSE)to examine the model.Finally we could obtain the WASP model with the minimum RMSE;(2)For the uncertainty of model parameters,we discussed the parameters of K12 C,K12T,KDC and KDT in WASP model.After the sensitivity analysis of model parameters,we chose the MCMC method for studying.Finallly,by statistical analyzing the posterior distribution of the parameters,we got the change intervals of 95% of the simulated results;(3)For the uncertainty of the results of model,we combined WASP model with neural network model and used the combination model to decrease and disperse the uncertainty of the method and structure of the model.At the same time,we chose the method of interval estimating and achieved the confidence interval of simulation results under the 5% significant level,which could make the simulation results more scientific and reliable.Finally,after studying on the treatment measures of water circulation,constructed wetland and the pollution control of rain runoff for common water,we scientifically expressed them to WASP model and got the scheme for improving and preserving the water quality of landscape water in airport economic zone according to the simulation results.