Monitoring And Analyzing The Lagoon Dynamics In China Using Remote Sensing Imagery

China has a long coast, widely developing the lagoon wetlands. Because of theevolution of the natural environment and human over exploitation, especially thereform and opening up in the last30years, the development and utilization of coastallagoons have been increasing prominently. The lagoon wetland area has beenshrinking, with the sediment accumulation, and the tidal inlets have been graduallyblocking seriously, parts of the lagoons have disappeared.At present, China has not been studying the coastal lagoons comprehensively andcompletely, having not understood of the status of the coastal lagoons. So that,mastering the numbers and distribution and finding out the real situation of the coastallagoons are imperative. Studying the geomorphology classification and ecologicalevolution stage of coastal lagoons and understanding the lagoon dynamics status inrecent years may help to grasp the development status of coastal lagoons and makeprotection measures. Investigating the formation, evolution, affection process anddynamics mechanism of the typical lagoon can help to propose lagoon ecologicalprotection and restoration approaches. It has practical significance to rationaldevelopment and utilization of natural resources in coastal lagoons.In this paper, the author monitor and analyze the coastal lagoon dynamicsnationwide using Remote Sensing imagery and then take the analysis of typicallagoon coast environmental changes of Bohe lagoon. China coastal lagoons aremainly distributed in Liaoning, Hebei, Shandong, Guangdong, Guangxi, Hainan andTaiwan provinces (or autonomous regions). Due to the paper work time and datalimitations, the scopes of the study are being determined to the major lagoondevelopment regions except Taiwan and Hainan Province. Firstly,102scenes ofimageries covered the study area are preprocessed using radiometric calibration, darktarget atmospheric correction, linear contrast stretching and geometric correction.Secondly, based on the data processed before and combined1:50000topographicmaps, the author determine the name of the lagoons, extracting lagoons position,coastline length and lagoon areas and analyzing the changing factors. In the last, thispaper take Bohe lagoon as example, studying the changes in the environmentsurrounding coast. The main work are as follows:(1) The paper proposes lagoon remote sensing classification system base on thesand geomorphology and classifies the coastal lagoons into6landform types: sandbarrier type, sand tsui type, bay head barrier type, tomboloof type and estuary type. It expands the application of remote sensing in geomorphology. The paper builds lagoonremote sensing classification system based on the development stages of evolution,the coastal lagoons are divided into3evolution stages of growth phase, old phase anddeath phase. Remote sensing interpretation keys of different lagoon types areestablished based on images combined with near-infrared, red and green bands withgeographic properties (color, texture and vicinity). The interpretation keys provide ascientific basis for the remote sensing identification and classification of coastallagoons.(2) The paper surveys China coastal lagoons names, types, numbers and thegeographic distribution, and then take the dynamics analysis. The results show thatthere were251lagoons in1979. It has disappeared19lagoons till2011. There is nonew lagoon born in the last32years.(3) The paper surveys China coastal lagoons coastline length and areainformation, studying the dynamics in1979,1990,2000and2011, and analyzes thedynamics. The data obtained support the researches of China lagoons evolution andmanagement. The technology of remote sensing provides the information extractionand analysis of lagoons a broad prospect. In this paper, an accuracy verificationmethod is put forward based on the polygon features in the same geographic location.(4) Driving causes of dynamics are analyzed in natural and anthropogenic factors.In this paper, the formation, development and evolution of White Sand Mouth lagoonare analyzed in waves, tides, sea level change and terrestrial runoff etc, and theformation and evolution of small lagoon outside the White Sand Mouth are analyzedin the view of coastal engineering.(5) Dynamics of the tidal flats and the flood tide delta of Bohe lagoon and outerlake are analyzed by TM data of2001and2010, the2images tidal level are in similar.Two underwater DEM data are produced by TIN interpolation method using2000and2009ocean chart data, and the accuracy of the DEM is verified. Based on remotesensing imagery, an underwater erosion and deposition quantitative method is putforward. Combined with slope, land cover types and vegetation coverage informationin2001, the intensity of soil erosion and sediment loss of Bohe surrounding basin arecalculated, and the erosion modulus of the basin is given. Combined with the changeof tidal flats and the flood tide delta, the change of underwater terrain, and the loss ofsoil and water, dynamics of Bohe surrounding coast are analyzed.