Author(s): S. Ahilan; M. Guan; N. G. Wright; P. A. Sleigh
Linked Author(s):
Keywords: Floodplain; Green infrastructure; Grey infrastructure; Urbanisation; Sediment dynamics
Abstract: This study explores the influence of floodplains on the sediment dynamics of Johnson Creek, a highly urbanised stream known for frequent flooding and which contains sections that do not meet water quality standards under the U. S. Federal Clean Water Act. The study area is focused on the downstream of Johnson Creek, the East Lent reach, where the bank of the creek has been reconfigured to reconnect the river to a restored floodplain on a 28-ha site to provide more space for the river to flow and be stored. The aim of this study is to investigate whether sediments from the watershed accumulate in the restored floodplain over a period of time or flushes out to the main Willamette River. A two dimensional hydromorphodynamic model has been adopted for the study region, which models suspended load sediment dynamics between the main channel and the floodplain. Simulation results indicate that about 30%sediment generated from the upstream deposited in the East Lents floodplain. As pollutants from the industries and agriculture lands are generally attached to the sediments, this can lead to serious long term health implications. Furthermore, sediment aggradation in the floodplain over a period of time can reduce the storage capacity of the flood basin.
Year: 2015