A New Framework for Modelling Fine Sediment Transport in Rivers Includes Flocculation to Inform Reservoir Management in Wildfire Impacted Watersheds

A - Papers appearing in refereed journals

Stone, M., Krishnappan, B. G., Silins, U., Emelko, M. B., Williams, C. H. S., Collins, A. L. and Spencer, S. A. 2021. A New Framework for Modelling Fine Sediment Transport in Rivers Includes Flocculation to Inform Reservoir Management in Wildfire Impacted Watersheds. Water. 13 (17), p. 2319. https://doi.org/10.3390/w13172319

AuthorsStone, M., Krishnappan, B. G., Silins, U., Emelko, M. B., Williams, C. H. S., Collins, A. L. and Spencer, S. A.
Abstract

Fine-grained cohesive sediment is the primary vector for nutrient and contaminant redistribution through aquatic systems and is a critical indicator of land disturbance. A critical limitation of most existing sediment transport models is that they assume that the transport characteristics of fine sediment can be described using the same approaches that are used for coarse-grained non-cohesive sediment, thereby ignoring the tendency of fine sediment to flocculate. Here, a modelling framework to simulate flow and fine sediment transport in the Crowsnest River, the Castle River, the Oldman River and the Oldman Reservoir after the 2003 Lost Creek wildfire in Alberta, Canada was developed and validated. It is the first to include explicit description of fine sediment deposition/erosion processes as a function of bed shear stress and the flocculation process. This framework integrates four existing numerical models: MOBED, RIVFLOC, RMA2 and RMA4 using river geometry, flow, fine suspended sediment characteristics and bathymetry data. Sediment concentration and particle size distributions computed by RIVFLOC were used as the upstream boundary condition for the reservoir dispersion model RMA4. The predicted particle size distributions and mass of fine river sediment deposited within various sections of the reservoir indicate that most of the fine sediment generated by the upstream disturbance deposits in the reservoir. Deposition patterns of sediment from wildfire-impacted landscapes were different than those from unburned landscapes because of differences in settling behaviour. These differences may lead to zones of relatively increased internal loading of phosphorus to reservoir water columns, thereby increasing the potential for algae proliferation. In light of the growing threats to water resources globally from wildfire, the generic framework described herein can be used to model propagation of fine river sediment and associated nutrients or contaminants to reservoirs under different flow conditions and land use scenarios. The framework is thereby a valuable tool to support decision making for water resources management and catchment planning.

KeywordsCohesive sediment; Erosion; Water supply; Turbidity; Gravel bed river; Ingress; Watershed management; Source water protection; Climate change adaptation; Landscape disturbance
Year of Publication2021
JournalWater
Journal citation13 (17), p. 2319
Digital Object Identifier (DOI)https://doi.org/10.3390/w13172319
Web address (URL)https://doi.org/10.3390/w13172319
Open accessPublished as ‘gold’ (paid) open access
FunderBiotechnology and Biological Sciences Research Council
Funder project or codeS2N - Soil to Nutrition - Work package 3 (WP3) - Sustainable intensification - optimisation at multiple scales
NSERC Discovery Grant 481 RGPIN-2020- 06963
Alberta Innovates Energy and Environment Solutions Grant AI-EES:2096
Alberta Innovates BIO Grant AI-BIO: Bio-13-009
Canada Research Chairs
ESRD/AAF (13GRFM15,15GRFFM11)
AI (1865, 2343)
NSERC (216984)
Publisher's version
Output statusPublished
Publication dates
Online24 Aug 2021
Publication process dates
Accepted20 Aug 2021
PublisherMDPI
ISSN2073-4441

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