We found a match
Your institution may have rights to this item. Sign in to continue.
- Title
System‐Wide Effects of Local Bed Disturbance on the Morphological Evolution of a Bifurcating Channel Network.
- Authors
Gao, Weilun; Shao, Dongdong; Wang, Zheng Bing; Zhu, Zhenchang; Yang, Zhifeng
- Abstract
Deltaic channel networks are important conduits for water and material supplies to the fluvial and coastal communities. However, increasing human interventions in river deltas have altered the topology and geometry of channel networks as well as their long‐term evolution. While the morphological evolution of a single channel has received extensive studies, the system‐wide morphological responses of channel networks to local disturbances remain largely unclear. Here we investigate the morphological responses of a bifurcating channel network subject to local disturbance of channel deepening due to dredging and sand mining through idealized simulations, and further compare the results with the reference scenarios of a single channel and theoretical analysis of the phase plane. The results show that the infilling of the local deepening is associated with the erosion of the entire branch, which also causes system‐wide effects on the siltation of the other branch. The morphological responses of the bifurcating channel network consist of a relatively short stage for the infilling of the local deepening followed by a relatively long stage for recovering the equilibrium configuration of the river bifurcation. The system‐wide effects of the local disturbance arise from the altered water surface slope and water partitioning downstream of the bifurcation due to the local deepening. Also, the prolonged recovery of the equilibrium configuration is consistent with theoretical analysis, which reveals a slow evolution of the bifurcation when approaching the equilibrium. Our results can help understand the long‐term morphological responses of large‐scale complex channel networks and inform water managements under increasing human interventions. Plain Language Summary: River channel networks with multiple interconnected channels are common in river deltas and are critical for the transport of water, sediment and nutrients to riverine and coastal wetlands. Intensive human interventions, such as dredging and sand mining, can lead to local disturbance of bed deepening in the channel networks. However, the system‐wide responses of the channel network to such local disturbances, for example, the morphological changes in neighboring channels as a result of a local deepening in one channel, remain elusive. In this study, we selected a bifurcating channel network, where the upstream river channel splits into two branches, as a simple demonstration case of a channel network to address this issue. We simulated the system‐wide responses of the bifurcating channel network to local deepening in one of the branches through numerical experiments in the Delft3D model. The results showed that the local deepening in one branch can affect the entire channel network, such as the siltation of the other branch. Moreover, the system‐wide effects on the channel network last much longer than a comparable single channel with the same total channel width and length. Our results can help inform the restoration and management of channel networks under increasing human interventions. Key Points: Local deepening in one branch can lead to a system‐wide morphological response of the bifurcating channel network in a two‐stage patternThe system‐wide effects arise from the altered water surface slope downstream of the bifurcation due to the local deepeningThe recovery of the equilibrium configuration of a bifurcating channel network is much longer than that of a comparable single channel
- Subjects
RIVER channels; COASTAL wetlands; LONG-Term Evolution (Telecommunications); WATER management; WATER supply; DREDGING
- Publication
Journal of Geophysical Research. Earth Surface, 2024, Vol 129, Issue 3, p1
- ISSN
2169-9003
- Publication type
Article
- DOI
10.1029/2023JF007514