Department of Earth and Environmental Sciences, Vanderbilt University, Nashville, Tennessee 37240; email:
Ann Rev Mar Sci. 2015;7:67-88. doi: 10.1146/annurev-marine-010213-135032. Epub 2014 Sep 17.
We present a review of the processes, morphology, and stratigraphy of the Ganges-Brahmaputra-Meghna delta (GBMD), including insights gained from detailed elevation data. The review shows that the GBMD is best characterized as a composite system, with different regions having morphologic and stratigraphic attributes of an upland fluvial fan delta; a lowland, backwater-reach delta; a downdrift tidal delta plain; and an offshore subaqueous-delta clinoform. These distinct areas of upland and lowland fluvial reaches and tidal dominance vary in time and space, and we distinguish late-Holocene phases of delta construction, maintenance, and decline similar to delta-lobe cycling in other systems. The overall stability of the GBMD landform, relative to many deltas, reflects the efficient, widespread dispersal of sediment by the large monsoon discharge and high-energy tides that affect this region. However, we do identify portions of the delta that are in decline and losing elevation relative to sea level owing to insufficient sediment delivery. These areas, some of which are well inland of the coast, represent those most at risk to the continued effect of sea-level rise.
我们对恒河-布拉马普特拉河-梅格纳三角洲（GBMD）的形成过程、形态和地层进行了综述，包括从详细的高程数据中获得的新认识。综述表明，GBMD 最好被描述为一个复合系统，不同区域具有山地扇三角洲、低地回水三角洲、顺岸潮汐三角洲平原和近海水下三角洲前积层的地貌和地层特征。这些高地和低地河流段以及潮汐控制的不同区域在时间和空间上存在差异，我们区分了晚全新世三角洲的建造、维持和衰退阶段，类似于其他系统中的三角洲叶瓣循环。与许多三角洲相比，GBMD 地貌的整体稳定性反映了季风排放和高能潮汐对该地区的大规模、高效、广泛的沉积物分散作用。然而，我们确实发现了一些三角洲地区正在衰退，相对于海平面失去了高程，这是由于沉积物输送不足造成的。这些地区中的一部分位于海岸的内陆，是最容易受到海平面持续上升影响的地区。
