This research was performed as part of an interdisciplinary project undertaken by the UK Blue-Green Cities (B-GC) Research Consortium (http://www.bluegreencities.ac.uk) with the Portland-Vancouver ULTRA (Urban Long-term Research Area) project (PVU, http://www.fsl.orst.edu/eco-p/ultra/), as part of the ‘Clean Water for All’ initiative (http://www.epsrc.ac.uk/funding/calls/cleanwaterforall/). The research reported in this short communication was funded by the UK Engineering and Physical Sciences Research Council under grant EP/K013661/1. Additional contributions came from the Environment Agency and Rivers Agency (Northern Ireland). PVU is funded by the National Science Foundation award #0948983.
Journal of Flood Risk Management
Contaminated sediments -- Environmental aspects, Urban runoff, Water quality -- Effect of land use on, Urbanization
This study investigated the delivery of contaminated sediments to the channel network by urban drainage systems in Johnson Creek in Oregon, USA. Concentrations of five heavy metal concentrations measured in 136 samples collected from 37 stormwater outfalls and 99 bed sampling points were analysed. While concentrations of zinc, cadmium and lead increased with distance downstream in Johnson Creek, this was not the case for chromium and copper. Zinc, copper, and cadmium concentrations in outfalls were significantly higher than those in the stream bed, indicating that stormwater runoff is responsible for delivering contaminated sediments to Johnson Creek. Zinc concentrations in outfalls were negatively associated with elevation and slope in the contributing subcatchment, and positively with impervious cover. However, no statistically significant relationships were found between the other heavy metal concentrations and sub-catchment variables. These findings demonstrate that relationships between sediment-related, heavy metal concentrations and subcatchment characteristics in this heterogeneous, rural-urban catchment are more complex than those found in situations where land-use is more segregated, questioning the applicability of commonly held assumptions regarding changes in the sources and delivery paths of flood-related, sediment-associated pollutants that accompany urbanisation.
Chang, H., Allen, D., Morse, J., & Mainali, J. (2018). Sources of contaminated flood sediments in a rural–urban catchment: Johnson Creek, Oregon. Journal of Flood Risk Management, e12496.