Processes In Land Use Change And Their Environmental Consequences In Coastal Area Of Fujian Province From The Perspective Of Land-sea Integration

The coastal zone is an area located between the ocean and the land.Under the double disturbances of climate change and human activities,the ecological environment of coastal zones has become increasingly prominent.Water pollution in the bays and offshore occurred frequently,resulting in serious degradation of terrestrial and saltwater aquatic ecosystem.The rapid urbanization process has triggered dramatic land use change in the coastal zone,and couple with natural factors such as climate change has brought about a series of negative environmental effects.The process and impact mechanisms need to be further explored.From the perspective of land-sea integration,this investigation looks into the interactions between the land use and its environmental effects.Minjiang watershed and 13 bays in Fujian Province was selected as a test site,the process mechanism of land use change,environmental effects of water quality and effects of soil erosion are studied.The results of this study may provide technical basis for land use planning,water resources protection and for land-sea integration management and integrated coastal zone management stratigies.Multivariate statistical analysis,geographic information technology,intensity analysis method,land use dynamic degree indices,RUSLE model and Environmental vulnerability assessment were used in this study to explore the land use change and its effects of coastal zones in Fujian province.The major conclusions are as follows:The spatio-temporal variations of process mechanism of land use change in 13 major bays in Fujian Province were systematically studied over the last 30 years.The rate of land use change in Minjiang Estuary,Quanzhou Bay,Shenhu Bay and Xiamen Bay was fastest during 2002-2009.The land use changes in other bays have also become more and more significant in the last 30 years.The loss of Cropland was quite common except for Fuqing Bay during the third time interval(2009-2017).The loss of Mudflat was considered as common in the last 30 years.The change of water body was relatively consistant except for the third period in Fuqing bay.The urbanization mainly occupied the Cropland.Compared with the traditional land dynamic index method,the Intensity Analysis method can better demonstrate the intrinsic transition process of land change.This study indicated that the growth of population,topographical factors and surrounding land use types,law and regulation,related policies and nature reserve are the main driving factors of land use change in the bay.This study revealed the spatio-temporal variations of water quality in 13 major bays in Fujian Province in the past three decades,and further explained the impact mechanism of water quality in the bay from the perspective of land use change.During the period of 1990-2016,the concentrations of inorganic nitrogen and active phosphate in the bay showed an overall upward trend.Inorganic nitrogen and active phosphate were the major indexes for determining the level of in Fujian.Inorganic nitrogen and active phosphate concentrations in the bay present significant spatial distribution characteristics.Inorganic nitrogen and active phosphate concentrations were at the highest in the estuary area.This study further proposed an optimization of water quality monitoring plan in the bay.Land use change in the bay was significantly correlated with water quality.The reduction of forest coverage,increase of builtup,large area reclamation,aquacultxure production were the major driving factors for lowing the water quality in those areas.This study explored the process mechanism of land use change and its soil erosion effect in the largest offshore watershed in Fujian Province in the past 30 years.The size of builtup area in Minjiang watershed increased sharply during 1985-2014.The urbanization process was mainly completed at the expense of the losses of forest and Cropland.The amount of annual soil erosion in Minjiang watershed and its sub-watersheds were characterized mainly light and moderate erosion types.Soil erosion in the watershed was driven by climate variability,land use change,and topographical factors.The impact of rainfall change on soil erosion was greater than that caused by land use.The land use change was more critical than rainfall change for driving force for the change of sediment yield rate.The systematic transitions from Woodland and Cropland/Built-up and Bareland were the major driving forces for the change of soil erosion and sediment yield rate.There was a significant positive correlation between soil erosion and TP.Thus soil erosion was an important factor leading to the increase of TP.The water quality of minjiang watershed had a significant influence on the water quality of minjiang estuary.Based on the above research,the environmental vulnerability assessment of the bay was further carred out.The results of environmental assessments showed that the environmental vulnerabilities of 13 major bays in Fujian Province range from moderate to extremely fragile.The environmental vulnerability of Minjiang watershed,Xinghua bay and Ji'zhen bay were classifies as severely fragile.The environmental vulnerability of Fuqing bay,Quanzhou bay,and Xiamen bay were considered to be extremely fragile.Management measures aim at solving the environmental problems of coastal zone in Fujian Province include controlling the quantity of pollutants entering the sea and developing comprehensive watershed management,coastal ecological restoration measures and ecological compensation,etc.