School of Marine Science and Engineering, Nanjing Normal University, Nanjing 210023, China.
Int J Environ Res Public Health. 2020 May 4;17(9):3191. doi: 10.3390/ijerph17093191.
The coastal tidal flats of the modern Radial Sand Ridges (RSRs) are typical silt-muddy tidal flats in Central Jiangsu Province. These tidal flats play a critical role in coastline protection and biodiversity conservation, and against storm surges, but have recently been displaying drastic changes in geomorphic dynamics because of human activities. However, a comprehensive understanding of spatiotemporal changes in tidal flats in RSRs remains lacking. Hence, we employed a novel remote sensing method by obtaining the instantaneous high/low tide line positions from over 112 scenes of Landsat satellite images of the study area from 1975 to 2017, which were used to track the recent evolution of the coastal tidal flats in the modern RSRs over the past four decades. We found that the shoreline of the tidal flats showed an advanced seaward trend, and the waterline of the tidal flat presented a gradual process during different periods. The total tidal flat area in the study area showed an obviously decreasing trend overall, and approximately 992 km of the tidal flat was lost. We also found that the coastal tidal flats in the modern RSRs were generally undergoing erosion in the low tidal flats, especially in the Northern Swing and Southern Swing areas, while the high tidal flats showed a slowed accretionary change. Land reclamation was the main factor affecting the reduction in the tidal flat area, as the reclamation area has increased by 1300 km, with an average of 35.14 km/year. In addition, the erosion of the tidal flats was associated with a reduced sediment supply. Our findings will provide useful information for local managers and researchers to support future environmental management because increasing demand for land and rising sea levels are expected in the future.
现代辐射状沙洲的沿海潮滩是江苏省中部典型的粉土淤泥质潮滩。这些潮滩在保护海岸线和生物多样性、抵御风暴潮方面发挥着关键作用，但由于人类活动，其地貌动力近年来发生了剧烈变化。然而，人们对辐射状沙洲潮滩的时空变化仍缺乏全面的了解。因此，我们采用了一种新的遥感方法，从 1975 年至 2017 年获取了研究区 112 景 Landsat 卫星图像的瞬时高低潮线位置，用于跟踪过去四十年现代辐射状沙洲沿海潮滩的近期演变。我们发现，滩涂的海岸线呈现出向海推进的趋势，滩涂的水线在不同时期呈现出逐渐变化的过程。研究区的总滩涂面积总体呈明显减少趋势，约有 992 公里的滩涂消失。我们还发现，现代辐射状沙洲的潮滩在低潮滩区普遍受到侵蚀，特别是在北摆和南摆地区，而高潮滩区则呈现出减缓的淤积变化。围填海是导致滩涂面积减少的主要因素，围填海区面积增加了 1300 平方公里，平均每年增加 35.14 平方公里。此外，滩涂的侵蚀与沉积物供应减少有关。我们的研究结果将为当地管理者和研究人员提供有用的信息，以支持未来的环境管理，因为未来预计对土地的需求会增加，海平面也会上升。
