Year of Award

2020

Document Type

Thesis

Degree Type

Master of Science (MS)

Degree Name

Geosciences

Other Degree Name/Area of Focus

Fluvial Geomorphology

Department or School/College

Geosciences

Committee Chair

Andrew C. Wilcox

Commitee Members

Marco P. Maneta, Ben Colman

Keywords

sediment balance, sediment modeling, sediment transport, river connectivity, watershed disturbance

Subject Categories

Geomorphology

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 sub-basins affected by large dams and wildfire. Model results highlight the importance of hydrologic conditions on post-wildfire sediment yield, and illustrate the spatial extent of dam-induced sediment deficit during a flood. We also combined SeRFE iv outputs for the mainstem Santa Clara River with a simple recruitment model of the invasive riparian plant Arundo donax, which is prevalent in the basin. This coupled modeling approach provided an ecogeomorphic framework for predicting source and sink areas of the plant. Results for these different scenarios highlight how 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.

Download

Included in

Geomorphology Commons

Share

COinS
 

© Copyright 2020 Jordan T. Gilbert