The role of deltaic tie channels for shoreline stability: a case study from the Huanghe (Yellow River) delta, China

Abstract

The dominant process for distributing sediment to floodplains is the relocation of a river by avulsion. After channel abandonment, tie channels convey sediment-laden water between the main channel and adjacent floodplain waterbodies (i.e. oxbows). Tie channels on deltas can also nourish lowing-lying abandoned distributary channels with sediment, which enhances the resiliency of coastlines. This research evaluates sediment delivery to an abandoned distributary channel that is now occupied by a subordinate tie channel. A lobe abandoned ten years ago due to an avulsion on Yellow River delta, China maintains a connection between the main river and the adjacent Bohai Sea; therefore, water flux here occurs due to both riverine and tidal process. Measurements of the tie channel location, collected using remote sensing data, indicate that it migrated laterally several hundred meters since inception, and channel width has reduced by a factor of ten. Several field data sets are needed to constrain the modern sediment delivery provided by this tie channel and tidal channels: measurements of water stage, flow velocity, turbidity and salinity within the tie channel and tidal channels, and detailed elevation surveys of both the tie and abandoned distributary channels. The relative importance of fluvial and marine sediment delivery will be evaluated throughout varying conditions, including fluvial base flow, fluvial flood flow, and winter storm events which are known to generate large storm surge. These data will be used to inform coastal engineering efforts that aim to maximize sediment accumulation and retention on coastlines.

AAPG Datapages/Search and Discovery Article #90351 © 2019 AAPG Foundation 2019 Grants-in-Aid Projects