Study On Characteristics Of Aquatic Ecological Environment Of Bohai Bay Based On Deterministics, Nondeterministics And The Coupled Model

The Bohai bay is a semi-enclosed muddy shallow water bay in the west of theBohai Sea. Pollutant discharging is serious and the water exchange ability of this bayis very weak here. With the rapid development of the economy and the rapid growthof population, the water quality of the Bohai bay has been becoming worse. Red tideoccurs frequently in this bay and the water ecological environment is under greatpressure. In order to protect the water ecological environment of the Bohai Bay, thehydrodynamic characteristics and the water ecological environment characteristicswas investigated based on deterministic model, nondeterministic model and thecoupled deterministic-nondeterministic model.Firstly, the hydrodynamic characteristics of the Bohai Bay were studied by usingthe deterministic model. The characteristic the residual current in the Bohai Bay wasanalyzed, and the influence of the shoreline change and wind on the residual currentwas also studied. The influence of wind on the water exchange of the Bohai Bay wasanalyzed seasonally. At the same time the water exchange between the different baysin the Bohai sea was analyzed by using the water exchange matrix. Due to the lack ofwind data, a special method for wind data processing was studied based on themeasured data, and a energy average wind data processing method was proposed.Secondly, the influence of pollutant discharging on the water ecologicalenvironment was studied by using the deterministic method. The types of the mainpollutants and the distribution characteristics of the pollutants discharge wereanalyzed. The characteristic of the response of the water quality to the land-sourceemission was studied. The seasonal variation characteristic of the runoff into Bohaibay was analyzed. Based on these data, the impact of the variation of runoff on thewater quality response characteristics was analyzed in wet season, median waterperiod and low water period. The influence of winds on the water quality response ofthe functional areas was analyzed seasonally.Thirdly, the nondeterministic Chlorophyll concentration prediction model wasestablished and optimized based on cellular automata(CA) and support vectormachine(SVM). By comparing the simulated results, the optimized parametercombination was obtained, and the nondeterministic Chlorophyll concentrationprediction model (the basic model) was established. According to Shelford’s Law ofTolerance and its supplement, an optimised model was developed using the series ofnine special models which correspond to a stage of sea surface temperature and thechlorophyll concentration, respectively. The results indicate that compared to the basic model the accuracy of the optimized model was improved.Fourthly, the mechanism-based deterministic model and the nondeterministicmodel (CA-SVM) were coupled together to predict Chlorophyll concentration, andthe coupled model was extended. The coupled model takes advantages of the twomodels. Compared to the nondeterministic model, the prediction accuracy of thecoupled model was improved.Finally, based on status quo of the waste water discharge around the Bohai Bay,the optimized configuration scheme of emission was proposed by using thedeterministic model and the total amount control method.