Comparison of One- and Two-Dimensional Flood Modeling in Urban Environments

Comparison of One- and Two-Dimensional Flood Modeling in Urban Environments

Sulochan Dhungel Michael E. Barber Robert L. Mahler 

Civil and Environmental Engineering, University of Utah, Salt Lake City, UT, U.S.A.

Soil Science Division, University of Idaho, Moscow, ID, U.S.A.

Page: 
356-366
|
DOI: 
https://doi.org/10.2495/SDP-V14-N4-356-366
Received: 
N/A
|
Accepted: 
N/A
|
Published: 
1 October 2019
| Citation

OPEN ACCESS

Abstract: 

The US Army Corps of Engineers Hydrologic Engineering Center recently released version of the River Analysis System (HEC-RAS) has added two-dimensional (2D) modeling capabilities to a decade old one-dimensional (1D) model dating back to HEC-2 developed in the 1970s. Several recent studies have indicated that 2D flood modeling is preferable in urban environments to better account for the complex topography caused by infrastructure. The newest version of HEC-RAS also allows users to simulate unsteady flow using either the Saint Venant equations or the diffusion wave (DW) equations using an implicit finite volume algorithm. The Saint Venant solution allows for turbulence and Coriolis effects to be accounted for with momentum additions. While applicable to a wider range of flood problems, the Saint Venant solution is slower and inherently less stable than the DW approach. We evaluate the similarities and differences between both 1D and 2D solution techniques using the lower Provo River in Utah as a prototypical urban river. Furthermore, since the 2D version of HEC-RAS is relatively new, we compared the HEC-RAS simulations to the 2D sedimentation and river hydraulics (SRH-2D) model developed by the U.S. Bureau of Reclamation. The method uses high resolution light detection and ranging imagery to determine floodplain topography and cross-section information for the channel properties. While no single river reach can adequately answer the question of whether 2D flood modeling produces superior results compared to 1D solutions, in this study the 1D unsteady flow model struggled to predict meandering stream phenomenon particularly because it was difficult to identify active flow versus storage areas as a function of flow depth. We conclude that temporal variations in most complex flow regimes will not be well modeled in 1D and that 2D modeling will produce superior results. 

Keywords: 

HEC-RAS, LiDAR, mesh generation, overbank storage, SRH-2D

  References

[1] Qi, H. & Altinakar, M.S., A GIS-based decision support system for integrated flood management under uncertainty with two dimensional numerical simulations. Environmental Modelling and Software, 26(6), pp. 817–821, 2011. https://doi.org/10.1016/j. envsoft.2010.11.006

[2] Tsakiris, G. & Bellos, V., 2014. A numerical model for two-dimensional flood routing in complex terrains. Water Resources Management, 28(5), pp. 1277–1291. https://doi. org/10.1007/s11269-014-0540-3

[3] Tayefi, V., Lane, S.N., Hardy, R.R. & Yu, D., A comparison of one- and two-dimensional approaches to modelling flood inundation over complex upland floodplains.  Hydrological Processes, 21(23), pp. 3190–3201, 2007. https://doi.org/10.1002/hyp.6523

[4] Bohorquez, P. & Darby, S.E., The use of one- and two-dimensional hydraulic modeling to reconstruct a glacial outburst flood in a steep alpine valley. Journal of Hydrology, 361(3–4), pp. 240–261, 2008. https://doi.org/10.1016/j.jhydrol.2008.07.043

[5] Brown, R.A. & Pasternack, G.B., Comparison of methods for analyzing salmon habitat rehabilitation designs for regulated rivers. River Research and Applications, 25(6), pp. 745–772, 2009. https://doi.org/10.1002/rra.1189

[6] Jones, k.E., Dahl, T.A. & Corum, Z.P., Modeled sedimentation in the lower White River county line levee setback, Washington State. U.S. Army Engineer Research and Development Center, ERDC/CHL TR-18-9, 2018.

[7] Gibson, S.A. & Pasternack, G.B., Selecting between one-dimensional and two-dimensional hydrodynamic models for ecohydraulic analysis. River Research and Applications, 32(6), pp. 1365–1381, 2016. https://doi.org/10.1002/rra.2972

[8] Horritt, M.S. & Bates, P.D., Evaluation of 1D and 2D numerical models for predicting river flood inundation. Journal of Hydrology, 268(1–3), pp. 87–99, 2002. https://doi. org/10.1016/s0022-1694(02)00121-x

[9] Fewtrell, T.J., Duncan, A., Sampson, C.C., Neal, J.C. & Bates, P.D., Benchmarking urban flood models of varying complexity and scale using high resolution terrestrial LiDAR data. Physics and Chemistry of the Earth, 36(7–8), pp. 281–291, 2011. https:// doi.org/10.1016/j.pce.2010.12.011

[10] Manfreda, S. Samela, C., Gioia, A. Consoli, G.G., Iacobellis, V., Giuzio, L. 2015. Flood-prone areas assessment using linear binary classifiers based on flood maps obtained from 1D and 2D hydraulic models. Natural Hazards, 79(2), pp. 735–754. https:// doi.org/10.1007/s11069-015-1869-5

[11] Zhang, T., Peng, L. & Feng, P., Evaluation of a 3D unstructured-mesh finite element model for dam-break floods. Computers & Fluids, 160, pp. 64–77, 2018. https://doi. org/10.1016/j.compfluid.2017.10.013

[12] Brunner, G.W., Hydraulic Reference Manual Version 5.0. U.S. Army Corps of  Engineers, Hydrologic Engineering Center, Davis, CA, 2016.

[13] Lai, Y.G., SRH-2D version 2: Theory and User’s Manual. U.S. Department of Interior, U.S. Bureau of Reclamation Denver, CO. 2008.