Skip to main content

Research Repository

Advanced Search

Reconstruction of subgrid scale topographic variability and its effect upon the spatial structure of three dimensional river flow

Casas, M.A.; Lane, S.N.; Hardy, R.J.; Benito, G.; Whiting, P.J.

Reconstruction of subgrid scale topographic variability and its effect upon the spatial structure of three dimensional river flow Thumbnail


Authors

M.A. Casas

S.N. Lane

G. Benito

P.J. Whiting



Abstract

A new approach to describing the associated topography at different scales in computational fluid dynamic applications to gravel bed rivers was developed. Surveyed topographic data were interpolated, using geostatistical methods, into different spatial discretizations, and grain-size data were used with fractal methods to reconstruct the microtopography at scales finer than the measurement (subgrid) scale. The combination of both scales of topography was then used to construct the spatial discretization of a three-dimensional finite volume Computational Fluid Dynamics (CFD) scheme where the topography was included using a mass flux scaling approach. The method was applied and tested on a 15 m stretch of Solfatara Creek, Wyoming, United States, using spatially distributed elevation and grain-size data. Model runs were undertaken for each topography using a steady state solution. This paper evaluates the impact of the model spatial discretization and additional reconstructed-variability upon the spatial structure of predicted three-dimensional flow. The paper shows how microtopography modifies the spatial structure of predicted flow at scales finer than measurement scale in terms of variability whereas the characteristic scale of predicted flow is determined by the CFD scale. Changes in microtopography modify the predicted mean velocity value by 3.6% for a mesh resolution of 5 cm whereas a change in the computational scale modifies model results by 60%. The paper also points out how the spatial variability of predicted velocities is determined by the topographic complexity at different scales of the input topographic model.

Citation

Casas, M., Lane, S., Hardy, R., Benito, G., & Whiting, P. (2010). Reconstruction of subgrid scale topographic variability and its effect upon the spatial structure of three dimensional river flow. Water Resources Research, 46(3), Article W03519. https://doi.org/10.1029/2009wr007756

Journal Article Type Article
Publication Date Mar 18, 2010
Deposit Date Aug 23, 2010
Publicly Available Date Mar 29, 2024
Journal Water Resources Research
Print ISSN 0043-1397
Electronic ISSN 1944-7973
Publisher Wiley
Peer Reviewed Peer Reviewed
Volume 46
Issue 3
Article Number W03519
DOI https://doi.org/10.1029/2009wr007756

Files

Published Journal Article (864 Kb)
PDF

Copyright Statement
Casas, M. A. and Lane, S. N. and Hardy, R. J. and Benito, G. and Whiting, P. J. (2010) 'Reconstruction of subgrid scale topographic variability and its effect upon the spatial structure of three dimensional river flow.', Water Resources Research., 46, 3, WR007756. To view the published open abstract, go to https://doi.org and enter the DOI.





You might also like



Downloadable Citations