The influence of floodplain restoration on flow and sediment dynamics in an urban river

Ahilan, S, Guan, M, Sleigh, A, Wright, N ORCID: https://orcid.org/0000-0002-1289-2830 and Chang, H, 2018. The influence of floodplain restoration on flow and sediment dynamics in an urban river. Journal of Flood Risk Management, 11, S986-S1001. ISSN 1753-318X

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Abstract

A study of floodplain sedimentation on a recently restored floodplain is presented. This study uses a two‐dimensional hydro‐morphodynamic model for predicting flow and suspended‐sediment dynamics in the downstream of Johnson Creek, the East Lents reach, where the bank of the river has been reconfigured to reconnect to a restored floodplain on a 0.26 km2 (26‐ha) site. The simulation scenarios include 10‐, 50‐, 100‐ and 500‐year event‐based deposition modelling of flood events and long‐term modelling using the 64 historical flood events between 1941 and 2014. Simulation results showed that the restored floodplain significantly attenuates the upstream flood peak by up to 25% at the downstream. Results also indicated that approximately 20%–30% of sediment from the upstream is deposited on the East Lents floodplain. Furthermore, deposited sediment over the simulated period (1941–2014) is approximately 0.1% of the basin's flood storage capacity; however, the reduction in the storage does not offset the overall flood resilience impact of the flood basin. The sediment conservation at the East Lents flood basin as predicted by the model reduces the annual sediment loading of the Johnson Creek by 1% at the confluence with Willamette River, providing both improved water quality and flood resilience further downstream.

Item Type:	Journal article
Publication Title:	Journal of Flood Risk Management
Creators:	Ahilan, S., Guan, M., Sleigh, A., Wright, N. and Chang, H.
Publisher:	Wiley-Blackwell
Date:	February 2018
Volume:	11
ISSN:	1753-318X
Identifiers:	Number Type 10.1111/jfr3.12251 DOI
Rights:	© 2016 The Authors. Journal of Flood Risk Management published by Chartered Institution of Water and Environmental Management and John Wiley & Sons Ltd. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
Divisions:	Professional Services > The Directorate
Record created by:	Linda Sullivan
Date Added:	29 Oct 2018 11:30
Last Modified:	29 Oct 2018 11:30
URI:	https://irep.ntu.ac.uk/id/eprint/34778

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