Sediment Routing and Floodplain Exchange (SeRFE): A Spatially Explicit Model of Sediment Balance and Connectivity Through River Networks

Abstract

Sediment regimes, i.e., the processes that recruit, transport, and store sediment, create the physical habitats that underpin river‐floodplain ecosystems. Natural and human‐induced disturbances that alter sediment regimes can have cascading effects on river and floodplain morphology, ecosystems, and a river's ability to provide ecosystem services, yet prediction of the response of sediment dynamics to disturbance is challenging. We developed the Sediment Routing and Floodplain Exchange (SeRFE) model, which is a network‐based, spatially explicit framework for modeling sediment recruitment to and subsequent transport through drainage networks. SeRFE additionally tracks the spatially and temporally variable balance between sediment supply and transport capacity. Simulations using SeRFE can account for various types of watershed disturbance and for channel‐floodplain sediment exchange. SeRFE is simple, adaptable, and can be run with widely available geospatial data and limited field data. The model is driven by real or user‐generated hydrographs, allowing the user to assess the combined effects of disturbance, channel‐floodplain interactions and particular flow scenarios on the propagation of disturbances throughout a drainage network, and the resulting impacts to reaches of interest. We tested the model in the Santa Clara River basin, Southern California, in subbasins affected by large dams and wildfire. Model results highlight the importance of hydrologic conditions on postwildfire sediment yield and illustrate the spatial extent of dam‐induced sediment deficit during a flood. SeRFE can provide contextual information on reach‐scale sediment balance conditions, sensitivity to altered sediment regimes, and potential for morphologic change for managers and practitioners working in disturbed watersheds.

An Ecogeomorphic Framework Coupling Sediment Modeling With Invasive Riparian Vegetation Dynamics

“…Future model improvements could explicitly incorporate the influence of vegetation on bank erosion using geospatial datasets of riparian species and extent. For a more complete discussion on limitations and assumptions of the SeRFE model, see Gilbert and Wilcox (2020).…”

“…To model basin sediment dynamics, we used the Sediment Routing and Floodplain Exchange (SeRFE) model (Gilbert & Wilcox, 2020). SeRFE is a spatially explicit, geospatial model that simulates sediment recruitment, transport, and deposition on a reach‐by‐reach basis at the scale of an entire basin.…”

“…Here, we present the elements of SeRFE essential to its use in our ecogeomorphic framework for linking sediment and invasive‐plant dynamics. Additional details on SeRFE are presented in Gilbert and Wilcox (2020).…”

“…With all of the necessary variables in Equations 2 and 3 thus parameterized, the SeRFE model can be applied to each reach of the input stream network for the duration of the flow record provided. For more detail on this calibration and discussion of limitations of this approach, see Gilbert and Wilcox (2020)…”

“…When ϴ = 1, bed mobilization and bank erosion initiate at the same flow, and ϴ > 1 means that additional stream power is required to initiate bank erosion. For the Santa Clara River basin, where channels are mostly labile, with mixed sand and gravel beds and incipient bed motion expected to begin well below bankfull, we obtained an average ϴ value of 4.2 to use in the modeling (Gilbert & Wilcox, 2020). With ϴ parameterized, bank erosion can be modeled using Equation 3.…”