Interplay between spatially explicit sediment sourcing, hierarchical river-network structure, and in-channel bed material sediment transport and storage dynamics

Authors

J. A. Czuba, Department of Civil, Environmental, and Geo-Engineering, St. Anthony Falls Laboratory, and Institute on the Environment, University of Minnesota, Twin Cities, Minneapolis, MN, United States
E. Foufoula-Georgiou, Department of Civil and Environmental Engineering, University of California, Irvine, CA, United States
K. B. Gran, Department of Earth and Environmental Sciences, University of Minnesota, Duluth, MN, United States
Patrick Belmont, Utah State UniversityFollow

Document Type

Article

Journal/Book Title/Conference

Journal of Geophysical Research: Earth Surface

Volume

122

Issue

5

Publisher

Blackwell Publishing Ltd

Publication Date

5-1-2017

Keywords

connectivity; emergent behavior; heavy tailed; river network; sediment bottleneck; sediment dynamics

First Page

1090

Last Page

1120

Abstract

Understanding how sediment moves along source to sink pathways through watersheds„from hillslopes to channels and in and out of floodplains„is a fundamental problem in geomorphology. We contribute to advancing this understanding by modeling the transport and in-channel storage dynamics of bed material sediment on a river network over a 600æyear time period. Specifically, we present spatiotemporal changes in bed sediment thickness along an entire river network to elucidate how river networks organize and process sediment supply. We apply our model to sand transport in the agricultural Greater Blue Earth River Basin in Minnesota. By casting the arrival of sediment to links of the network as a Poisson process, we derive analytically (under supply-limited conditions) the time-averaged probability distribution function of bed sediment thickness for each link of the river network for any spatial distribution of inputs. Under transport-limited conditions, the analytical assumptions of the Poisson arrival process are violated (due to in-channel storage dynamics) where we find large fluctuations and periodicity in the time series of bed sediment thickness. The time series of bed sediment thickness is the result of dynamics on a network in propagating, altering, and amalgamating sediment inputs in sometimes unexpected ways. One key insight gleaned from the model is that there can be a small fraction of reaches with relatively low-transport capacity within a nonequilibrium river network acting as ñbottlenecksî that control sediment to downstream reaches, whereby fluctuations in bed elevation can dissociate from signals in sediment supply. ©2017. American Geophysical Union. All Rights Reserved.

Recommended Citation

Czuba, J. A.; Foufoula-Georgiou, E.; Gran, K. B.; and Belmont, Patrick, "Interplay between spatially explicit sediment sourcing, hierarchical river-network structure, and in-channel bed material sediment transport and storage dynamics" (2017). Watershed Sciences Faculty Publications. Paper 999.
https://digitalcommons.usu.edu/wats_facpub/999