The Spatio-temporal Analysis Of Su-hu Mainland Coastline Changes Since1973

Yangtze Delta is an important economic centre in China. With rapid developmentof economy and explosive growth of population, the land resource is extremelydeficient. In order to meet the requirements of social and economic development,massive reclamation activities have been carried out on the coast of Jiangsu andShanghai, which have a significant impact on the coastal ecological environment.Thus, it is necessary to understand the temporal and spatial changes as well as graspthe conditions of human activities over the past decades for scientific and rationaldevelopment and protection in Su hu coastal area. However, the long time serialstudies on the overall changes of Su hu coastal zone is insufficient at present.In view of the above questions, shoreline and reclamation information wasextracted using the Landsat data obtained in1973,1981,1990,2002and2013respectively. Then the shoreline changing rate, land changing area and reclamationarea were calculated. Based on the above information, the temporal and spatialdistributions of Su hu coastal changes were analyzed. The main contents andconclusions are as follows.(1) The Remote Sensing-based Shoreline Uncertainty AnalysisThree main methods for shoreline uncertainty analysis, which are one based onerror sources, one based on Monte Carlo simulation and another one based on a moreprecise shoreline, were realized and then evaluated. The results revealed that the firstmethod can be applied to topographic maps, aerial and satellite images and otherimaging data. Under the circumstance that the probability density distribution of thevarious error sources was determined, the second one was suitable for both imagingdata and non imaging data. The method based on a more precise shoreline could getthe more precise results, but it was far more difficult to obtain the data of the sametime phase. With the methods mentioned above, the shoreline uncertainties of1973,1981,1990,2002and2013were acquired, which were48.42m,34.00m,15.15m,23.02m and22.28m respectively. All the uncertainties were smaller than one pixel,which means that all methods achieved the accuracy requirements of shoreline interpreted by the Landsat image.(2) Temporal-spatial Analysis of Shoreline Changes in Su-hu Coastal ZoneThe spatiotemporal characteristics of Su hu coastal deposition and erosionchanges were obtained by analyzing the shoreline changing rate, land changing areaof different coastal segments during different time frames，and the causes. The resultsindicated that Su hu coast showed a trend of accretion, with a land area increased1832.22km2and shoreline advancing rate of43.58m/a. During the study period, theaccretion velocity firstly decreased and then increased, which advanced the fastest in20022013, followed by19902002, and the slowest in19811990. In the study area,only the abandoned Huanghe Estury showed a trend of erosion. Haizhou Bay coast,the coast inside the radiation sandbar, Yangtze River estuary coast and Hangzhou Baycoast were all in a situation of accretion. And seaward speed in the coast inside theradiation sandbar was23times faster than other segments. By analyzing the relevantliterature and satellite image, it turned out the rapid accretion in Su hu coast wasmainly caused by aquaculture, port construction and other human activities, and theerosion was mainly caused by the shift of Yellow River’s route, the reduction of thesilt and other natural factors.(3) Temporal-spatial Analysis of Reclamation on Su-Hu CoastThe temporal spatial characteristics of reclamation in Su Hu coastal zone wereobtained. In19732013, the total reclamation area on the Su hu coast was1690.33km2. And the reclamation rate increased after the first decrease. In20022013, thereclamation area was650.72km2, as was the largest; while in19811990, the areawas only79.88km2, as was the minimum. The reclamation in Jiangsu was severerthan that in Shanghai. The reclamation area of Jiangsu and Shanghai were1400.50km2and289.83km2respectively. Reclamation mainly occurred in Yanchengand Nantong of Jiangsu, and Pudong New Area of Shanghai. The mainly reclamationtype was aquaculture pond. And agricultural reclamation and ports reclamation had aless great proportion.