| The expansion of land for aquaculture has led to a sharp decline in the area of natural wetlands and a loss of ecosystem diversity.In order to promote the "scientific development and safe development" of tidal flat resources,the study of the sea evolution process and trends in coastal aquaculture has begun to receive attention.Yancheng City,Jiangsu Province has abundant tidal flat resources,and coastal aquaculture land is one of the main forms of exploitation along the beach resources.Timely and accurate information on the temporal and spatial changes of land used for aquaculture is an important basis for the protection and rational development and utilization of beach resources in Yancheng.However,from the current perspective,the information on the land used for aquaculture is mostly from statistical reports,lacking information visualization and dynamic analysis results of spatial visualization.Therefore,understanding the evolution characteristics of coastal aquaculture land in Yancheng City and studying the simulation of the future distribution trend of the aquaculture land is of great value and significance to the planning and management of the aquaculture land.This article took Yancheng coastal sea aquaculture land as the research object,selects remote sensing images of four periods of 1998,2004,2010 and 2016 as data sources,and used RS and GIS technology to interpret the remote sensing image and revealed Characteristics of Evolvement of Coastal Aquaculture Land in Yancheng City.At the same time,Dafeng District was selected as a typical area to collect data on DEM and river port locations in the typical area,and the relevant policy guidelines for coastal aquaculture land use in the region were compiled,combined with the characteristics of evolution of coastal aquaculture land in Dafeng District,transformation rules were determined,and constraints were applied.The CA-Markov model simulated the distribution of coastal aquiculture land in the study area in the future and combined the simulation results to analyze the future development trend of the coastal aquaculture land.The specific conclusions are as follows:(1)From 1998 to 2016,the sea area for coastal aquaculture in Yancheng City increased at first and then decreased,from 258.11km2 in 1998 to 689.79km2 in 2010,and then to 664.67km2 in 2016.However,in different shore sections,changes in the area of sea aquaculture in Yancheng City show regional differences:the land used for aquaculture at the port from the irrigation estuary to the abandonment of the Yellow River was in a stable state,and the coastal section near the Sheyang Estuary increased first and then declined.As for the trend,the section between Doulong Port and Laoba Port has continued to grow steadily.(2)In the past 20 years,changes in policies,shoreline scouring,and industrial structure caused different spatial patterns of coastal aquaculture land use in each bank segment:the stable pattern of aquiculture land for aquaculture at the estuaries to waste abandonment of the Yellow River,and aquaculture.The center of gravity hardly migrated;the center of aquaculture land from the Yellow River estuary to Duolong Port oscillated back and forth along the coast line near the Sheyang estuary;the shoreline of the shore from Doulong Harbor to Laoba Port moved outward first along the coastline and then along the coast.The direction of the line was significantly shifted southwards.(3)From the point of view of landscape evolution,the development and utilization of coastal aquaculture land in Yancheng had become increasingly fragmented,and the spatial distribution of aquaculture land tend to be decentralized.The management department should pay attention to it,and adopt scientific and reasonable planning measures to minimize the fragmentation of the coastal aquaculture land,realize the intensive use of the beach resources,and improve the stability of the regional ecosystem.(4)Based on the CA-Markov model,the conversion rules for the evolution of marine aquiculture land were established.The simulation accuracy of the model for the coastal aquaculture land use reached 89.4%.The model is better for the simulation of the expansion area of the sea aquaculture land.Simulation results show that the sea-breeding aquaculture in the Dafeng area mainly presents a tendency of spreading to the sea side,and the expansion area will be mainly concentrated near the Simaoyou Estuary and Chuandong Port.Fragments with more scattered distribution will be connected into pieces,and the outer edge line of the sea for aquaculture will gradually show a parallel expansion trend of the coastline. |
