The Jamuna is a major braided river of Bangladesh and poses enormous challenges related to flooding, erosion, and sedimentation. Effective river management requires an understanding of the Jamuna’s sediment transport dynamics and channel morphology. Yet, developing that understanding is hindered by a lack of topographic data for the river corridor. In this study, the waterline method was applied to a 65 km reach of the Jamuna to derive river channel and floodplain topography above the low water level. The analysis relies on surface water detection from Sentinel-1 and Sentinel-2 data, along with in-situ water level observations, to generate river-floodplain DEMs for the years 2016–2019. Morphologic change was assessed through DEMs of difference for sequential years and for the overall study period. A quantitative uncertainty analysis was conducted to characterize errors in the waterline DEMs, vertical change detection, and gross and net volumetric changes. The results indicate that gross annual erosion and accretion volumes have a similar order of magnitude to contemporary estimates of the river’s sediment influx. The study highlights that localized and reach-scale lateral exchange is a key component of the overall sediment budget. Finally, the uncertainty analysis framework provides insight and recommendations for how errors can be assessed and reduced in future waterline applications.

中文翻译：

---

结合地球观测与地面数据评估河流地形和形态变化：贾木纳河下游案例研究


贾穆纳河是孟加拉国的一条主要辫状河，带来了与洪水、侵蚀和沉积有关的巨大挑战。有效的河流管理需要了解贾穆纳河的沉积物输送动态和河道形态。然而，由于缺乏河流走廊的地形数据，这种理解的发展受到阻碍。在这项研究中，水线法应用于贾穆纳河 65 公里的河段，以获得低水位以上的河道和漫滩地形。该分析依赖于 Sentinel-1 和 Sentinel-2 数据的地表水检测以及原位水位观测，以生成 2016-2019 年的河流洪泛区 DEM。通过连续年份和整个研究期间的 DEM 差异来评估形态变化。进行定量不确定性分析来表征水线 DEM、垂直变化检测以及总体积和净体积变化中的误差。结果表明，年总侵蚀量和累积量与当代河流泥沙流入量的估计量具有相似的数量级。该研究强调，局部和河段规模的横向交换是总体沉积物预算的关键组成部分。最后，不确定性分析框架为如何评估和减少未来水线应用中的误差提供了见解和建议。