Predicting Water and Sediment Partitioning in a Delta Channel Network Under Varying Discharge Conditions

Abstract

Channel bifurcations control the distribution of water and sediment in deltas, and the routing of these materials facilitates land building in coastal regions. Yet few practical methods exist to provide accurate predictions of flow partitioning at multiple bifurcations within a distributary channel network. Herein, multiple nodal relations that predict flow partitioning at individual bifurcations, utilizing various hydraulic and channel planform parameters, are tested against field data collected from the Selenga River delta, Russia. The data set includes 2.5 months of time-continuous, synoptic measurements of water and sediment discharge partitioning covering a flood hydrograph. Results show that width, sinuosity, and bifurcation angle are the best remotely sensed, while cross-sectional area and flow depth are the best field measured nodal relation variables to predict flow partitioning. These nodal relations are incorporated into a graph model, thus developing a generalized framework that predicts partitioning of water discharge and total, suspended, and bedload sediment discharge in deltas. Results from the model tested well against field data produced for the Wax Lake, Selenga, and Lena River deltas. When solely using remotely sensed variables, the generalized framework is especially suitable for modeling applications in large-scale delta systems, where data and field accessibility are limited.

Impacts of Engineered Diversions and Natural Avulsions on Delta‐Lobe Stability

“…This is consistent with observations of deltas that evolve over longer timescales than the Huanghe: the Mississippi River delta system experiences major lobe abandonment over centuries to millennia, and its bayou network is an example of a persistent connection between the main and abandoned channels (e.g., bayous LaFourche, Maringuoin, and Teche; Roberts, 1997). Similar examples exist for other river delta systems covering a range of sizes (e.g., Brazos River delta, Taha & Anderson, 2007; Selenga River delta, Dong et al., 2020). Even in lowland river systems, tie channels maintain a persistent freshwater connection to abandoned channels (Day et al., 2008; Rowland et al., 2009, 2005).…”

Stable ≠ Sustainable: Delta Dynamics Versus the Human Need for Stability

“…2). Work in other systems has shown that network structure can also be used to estimate flux partitioning and the delivery of fluxes at the shore (Tejedor et al, 2015) and that estimation of nutrient and sediment fluxes can be addressed in similar ways (Dong et al, 2020;Knights et al, 2020).…”

Competing feedback in an idealized tide-influenced delta network

“…In Section 2.2, we have seen that in the case of a single bifurcation tides exert a stabilizing effect that prevents the closure of one of the two branches in the long-term. However, deltaic networks are formed by several interconnected bifurcations that can interact with each other [58,59,60,61,16].…”