Sediment dispersal and accumulation off the Ayeyarwady delta – Tectonic and oceanographic controls

Connecting Sediment Retention to Distributary‐Channel Hydrodynamics and Sediment Dynamics in a Tide‐dominated Delta: The Ayeyarwady Delta, Myanmar

“…While estuarine processes are forced toward or onto the shelf, the ocean conditions are energetic seaward of the Ganges‐Brahmaputra Delta and the western Ayeyarwady Delta (Figure 10). Sediment discharged from distributaries is rapidly advected offshore or into a sheltered gulf (Goodbred & Kuehl, 1999; Kuehl et al., 2019; Liu et al., 2020). In the Mekong Delta and the eastern Ayeyarwady Delta, wave conditions are generally quiescent during the high‐flow season, and sediment is retained close to the mouths of distributaries (Eidam et al., 2017).…”

“…Figure10. Cartoons of ocean conditions and sediment dynamics in the Ganges-Brahmaputra(Wilson & Goodbred, 2015), Ayeyarwady (this study andKuehl et al, 2019), and Mekong(Ogston et al, 2017) Deltas during the NE and SW monsoon seasons. Prevailing currents are indicated with white arrows and the wave climate is indicated with scaled wave symbols.…”

“…The Ayeyarwady River (Figure 1) drains through the Central Myanmar Basin, between the Indo‐Burman Range to the west and the Pegu Range to the east. Previous in situ studies have focused on improving estimates of the fluvial and sediment discharge at the inland apex of the Delta (Baronas et al., 2020; Furuichi et al., 2009; Gordon, 1885; Robinson et al., 2007) and on the fate of sediment in the Gulf of Mottoma (Martaban) and adjacent shelf (Kuehl et al., 2019; Liu et al., 2020).…”

“…Prevailing currents flow clockwise around the Gulf (from west to east along the delta shoreline) during the SW monsoon, and counterclockwise during the NE monsoon. Wave energy increases during the SW monsoon, especially along the western portion of the delta (Kuehl et al., 2019). The three distributaries studied here represent this full range of seasonally varying wave conditions.…”

“…The strong tidal currents in the upper Gulf continually rework the bed and maintain elevated suspended‐sediment concentrations (Ramaswamy et al., 2004). Sediment accumulation is most rapid in the southeastern region of the Gulf, where accommodation space is generated by crustal movement associated with the Sagaing Fault (Kuehl et al., 2019). Overall, examining the western Pathein, central Bogale, and eastern Yangon distributaries provides insight into the full range of hydrodynamic and sedimentary conditions across the Ayeyarwady Delta.…”