The Ganges deltaic coast of Bangladesh experiences an incessant movement over the time. Understanding the shoreline movement of this alluvial delta and a suitable method to calculate the rate of change poses a challenge for this highly dynamic coast having erosion and accretion. Using GIS and multi temporal LANDSAT images, the study investigated the positional change of the Ganges deltaic shoreline for the period of 1977–2017. LANDSAT images were radiometrically corrected and a spectral index i.e., normalized difference water index (NDWI) was applied to differentiate water and land features. A histogram based Otsu’s Binary thresholding method along with image based visual interpretation was used to extract the shorelines. Net changes of shoreline position were statistically calculated using three different techniques, namely; End Point Rate (EPR), Linear Regression Rate (LRR) and Weighted Linear Regression (WLR). A comparison between the techniques was also made to choose and evaluate the suitable statistical technique to estimate the rate of shoreline change for this alluvial delta. Analyses showed that LRR technique had less positional uncertainty in compare to EPR and WLR, although at a particular transect the techniques were closely correlated. The EPR, WLR and LRR technique showed that the shoreline is experiencing landward movement (erosion) with an average rate of 0.62 m/yr, 0.96 m/yr and 0.27 m/yr respectively. Moreover, a high erosion rate of 5 m/yr at the mangrove forest area of the GDC is a great concern for the existence of the mangrove forest. During 1977–2017, an overall 6.29 sq. km land area has been lost although significant land depositions were observed at the river estuaries. This study revealed the spatiotemporal trend of shoreline position of the Ganges deltaic coast and that would be beneficial for the coastal management and planning of the region.

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使用地理空间工具进行海岸线变化评估：孟加拉国恒河三角洲海岸研究

随着时间的流逝，孟加拉国的恒河三角洲海岸经历了持续不断的运动。理解这个冲积三角洲的海岸线运动以及计算变化率的合适方法，对于这种具有侵蚀和积聚的高动态海岸构成了挑战。使用GIS和多时态LANDSAT图像，研究调查了1977-2017年期间恒河三角洲海岸线的位置变化。对LANDSAT图像进行了辐射校正，并应用了光谱指数即归一化差水指数（NDWI）来区分水和土地特征。使用基于直方图的Otsu二进制阈值方法以及基于图像的视觉解释来提取海岸线。使用三种不同的技术，统计地计算出海岸线位置的净变化：端点速率（EPR），线性回归率（LRR）和加权线性回归（WLR）。还对这些技术进行了比较，以选择和评估合适的统计技术，以估算该冲积三角洲的海岸线变化率。分析表明，与EPR和WLR相比，LRR技术具有较小的位置不确定性，尽管在特定的横断面技术紧密相关。EPR，WLR和LRR技术显示，海岸线正在向陆地移动（侵蚀），平均速率分别为0.62 m / yr，0.96 m / yr和0.27 m / yr。此外，GDC的红树林面积的5 m / yr的高侵蚀率引起了对红树林的严重关注。在1977–2017年期间，总面积为6.29平方米。尽管在河口观察到大量土地沉积，但公里数的土地面积已经消失。这项研究揭示了恒河三角洲海岸海岸线位置的时空趋势，这将有利于该地区的海岸管理和规划。