Study On Some Basic Problems Of Integrated Coastal Water Environment Management And Its Application

The coastal zone is the important region for exploiting and utilizing the marine resources, and it is also the area affected by human activities remarkably. With the rapid socio-economic development, human exploitation activities and migration to coastal areas is increasing continually, which put great pressures on the coastal zones and cause many problems such as marine resource exhaustion, water quality deterioration and eco-environmental degradation, etc. Therefore, it is urgent to establish an objective and effective integrated coastal management method to solve these serious problems. Aimed to provide some technical supports for improving the integrated coastal environment management, restoring the coastal environment, and then promoting the sustainable development for coastal zones, some basic problems about the theories, methods and practices are further discussed for the integrated coastal environment management with the Bohai Bay coastal zone as an example.Firstly, the theories of integrated coastal management are summarized through reviewing the available research results, and an integrated coastal environment management framework is set up in the viewpoint of sea-land integration based on the thought of harmonies development between eco-environment and socio-economy.Then multi-disciplinary theories, such as environmental fluid mechanics, information engineering, environmental science, management science, marine ecology, as well as numerical simulation techniques and so on, are used to build the synthetic evaluation, prediction and improving technical system of coastal zones.The key problem of synthetic evaluation is to establish an indicator system and set up a series of effective evaluation methods. In this paper, the indicator system is established on the principles and methods of systematic analysis, and the coastal eco-environment indicator system for Bohai Bay is set up which includes the nutrition factors, the environmental factors and the ecological factors. Then the synthetic evaluation is applied to the coastal eco-environment of Bohai Bay. The results show that the present state of coastal environment is not good, for example the inorganic nitrogen pollution is serious and the bio-diversity index is low. These are mainly caused by the land discharged pollutants and exploitation activities along the coastline.Prediction model is usually applied to simulate and analyze the variations of water eco-environment. It is an important method in the integrated water environmental management, while one key point is to determine the model parameters. In this paper, with the theory of parameter inversion, an attempt is carried out on the inversion of the dispersion coefficient in the water quality model for shallow water. The identification of the dispersion coefficient is turned into the numerical iterative processes relying on the field survey data in the study area, and its optimum value is obtained automatically. This method is proved to be effective through the application to the Bohai Bay, and it can be expected to apply to other similar problems in coastal waters.After the calibration and verification, the prediction model is applied to simulate and synthetically analyze the influence of the human-induced changes of pollutant discharge and shoreline on the coastal waters. Details are given about the variations of hydrodynamic characteristics and pollutant transport under the influence of reclamation engineering. Coupling with the in-situ radioactive isotope investigation, the sediment transport in the western Bohai Bay is studied. Analysis is also carried out about the impact of the pulse release of pollutant caused by different operation mode of sluice on the river estuary. The influence on the local eco-environment, which induced by the discharging of concentrated sea water with high salinity and temperature from the seawater desalination project, is analyzed.At last, the methods of protecting and improving the water environment of coastal zones are discussed such as controlling the amount of pollution discharged into the sea waters and increasing the runoff into sea. In the viewpoint of land-sea integration, the allocation method of the allowable pollution load is studied, and the total amount control of Bohai Bay coastal area is determined. Furthermore, the improving state of coastal waters is analyzed for different scenes of increasing runoff to the coastal waters. After constructing the evaluation index system of harmonious development between the coastal marine environment and the economy, the levels of harmonious development in the coastal areas of Bohai Bay in recent 10 years is studied, and some methods and suggestions are presented for the integrated coastal management of Bohai Bay.