Study On Size Control Of Coastal Reclamation In China

With the acceleration of urbanization in China,a demand for land due to urban large-scale construction and development is increasing.Coastal reclamation(CR)is a prevailing approach to tackle the contradiction between the coastal land shortage and the growing demand of living space for human beings.Enormous social and economic benefits are being brought from CR,and CR also brings a series of environmental problems at the same time.Since the 21st century,this oceanic-oriented development has become more frequent.In this sense,this study calculated suitable area of these coastal reclamation projects(CRPs)when the reclamation brought no negative impacts on marine environment.This study provides a scientific reference for effective management of coastal reclamation and future environmental impact researches when new CRPs are proposed.In order to follow the natural laws of coastal environment and protect the marine ecosystem,an integrated framework employing a fuzzy comprehensive evaluation method and analytic hierarchy process(AHP)was applied to the suitability evaluation for CR in Haizhou Bay.For the evaluation index system,there are two elements:(1)the marine environment and natural resources element;(2)the social and economic development element.The marine environment and natural resources element is given priority.The results showed that the four suitability classes,namely Suitable,Weakly Suitable,Unsuitable and Forbidden accounted for 31.49%,11.04%,26.34%and 31.13%in the total study area,respectively.Meanwhile,the proportion of coastline that is unsuitable for reclamation(Unsuitable and Forbidden)occupied 57.47%,exceeded a half of the total amount.Suitable and weakly suitable coastline for reclamation were located mainly in the northern and central part of this study area.The unsuitable and forbidden ones were concentrated in the southern portion of this study area.According to the suitability evaluation result for CR,an integrated framework based on coastal hydrodynamics was established.Then it was applied to the feasibility evaluation of multiple CRPs for screening out the optimal reclamation scenario in Haizhou Bay.According to the three evaluation indicators,tidal prism,flow velocity and water exchange rate gradually decreased as the reclamation area expanded.These reclamation projects had left notable negative effects on the tidal prism and small negative effects on the flow field and finally on the water exchange rate.With regard to four reclamation scenarios,scenario IV had the minimum negative impacts on the hydrodynamic condition and the maximum allowable area for CR that was 105 km2.Scenario ? also caused tiny negative effects on the hydrodynamic condition and owned the same allowable reclamation area with the scenario ?.Scenario ? brought a great negative impact on the hydrodynamic condition.Moreover,scenario ?produced the greatest impact on hydrodynamic environment,and the allowable reclamation area was only 49 km2.Therefore,scenario ? is the optimal reclamation scenario,scenarios ? and ? the alternative ones,scenario ? the worst one.On the basis of the hydrodynamic evaluation results,this study established an integrated evaluation framework based on water environmental capacity for assessment on the potential environmental impact resulted from CRPs.According to the water quality status and positions of CRPs in Haizhou Bay,the environmental capacity of four major pollutants were calculated to forecast the suitable area of CRPs.The results indicated that these reclamation projects had notable negative effects on the environmental capacity of four major pollutants.Here,the rank order is listed according to their harm on seawater quality:PO4-P>NH4-N>NOx-N>COD.In three reclamation alternative scenarios;scenario ? led to the minimum negative impacts on the environmental capacity,scenario ? followed and scenarios I was the worst one.Hence,scenario ? is the optimal reclamation scenario,and the suitable area of CRPs was 83km2 in Haizhou Bay.In this study,in order to obtain the most appropriate location and extent for CRPs,marine natural environments,including geology,topography,hydrology,ecology,social and economic development in this zone were considered and comprehensively evaluated.It provides a theoretical basis and data for future space selection of CRPs.Based on the CR suitability evaluation,we overlaid multiple CRPs and evaluated their cumulative effects on marine environment in different scenarios,considering coastal hydrodynamic condition and water environmental capacity.Then we calculated the allowable reclamation area of CRPs in Haizhou Bay.This paper provides a preliminary exploration on methodology and ideas for the suitable size of CRPs.Besides,the optimal reclamation scenario chosen in this study can serve as a theoretical reference for Jiangsu Province and Lianyungang coastline development.The methods proposed in this study can also provide a reference for further CRPs research in the same type of coastline.