Monitoring the channel process of a stream restoration project in an urbanizing watershed: a case study of Kelley Creek, Oregon, USA

Abstract

Pacific Northwest (PNW) streams in the United States were impacted by the 20th century development, when removal of instream structure and channelization degraded an aquatic habitat. The lower Kelley Creek in southeast Portland, USA was channelized during the 1930's Works Progress Administration (WPA) projects. Stream restoration reintroduced pool-riffle sequences and heterogeneous substrates to protect salmonids while mitigating impacts from flooding. We investigated whether the restored pool-riffle morphology changed substantially following effective discharge events. We examined channel forms for four reaches representing three time periods-pre-development (two reference reaches), development and restoration. We conducted thalweg profiles, cross-sections and pebble counts along the reaches to examine how channel geometry, residual pool dimensions and particle size distribution changed following effective discharge events. The effective discharge flows altered the restoration reach more substantially than the reference reaches. The restoration reach decreased in median particle size, and its cross-sectional geometry aggraded near its margins. However, the residual pool morphology remained in equilibrium. Richardson Creek's reference reach degraded at the substrate level, while Kelley Creek's reference reach remained in equilibrium. The restoration reach's aggradation may have resulted from sedimentation along the nearby Johnson Creek. In contrast, Richardson Creek's degradation occurred as upstream land use may have augmented flows. Stream channels with low gradient pool-riffle morphologies are ideal for salmonid spawning and rearing and should be protected and restored within urban corridors. The findings of our study suggest that the connectivity of streams and the dynamic fluvial geomorphology of stream channels should be considered for stream restoration projects in humid temperate climates.

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

“…), water quality (Sonoda et al . ; Sonoda and Yeakley ; Pratt and Chang ; Chen and Chang ) and ecological problems (Hook and Yeakley ; Levell and Chang ) attributable to agricultural practices and urban development in the watershed.…”

Ecological engineering restoration of a non-point source polluted river in Northern China

“…In addition, the multi-functional ecological ponds further promoted the economic benefits to the local residents due to the overall improvement of the environment. Ecological engineering has been extensively achieved in Western countries, especially for the improvement of the water quality, habitat, and continuity of the river, as well as for the restoration of flooded areas (Mitsch et al, 2006;Levell and Chang, 2008;Morten et al, 2007;Yasuharu et al, 2005). However, these countries have focused more on the improvement of the ecosystem structure and the environment benefits, and seldom on economic benefits.…”

Environmental stressor gradients hierarchically regulate macrozoobenthic community turnover in lotic systems of Northern Italy

“…Interventions on substrate conditions must be followed by additional interventions in flow conditions in order to be successful with a more permanent effect. For example, it was observed that excessive fine sediment entry from adjacent croplands upstream of a restored system counteracted physical habitat improvements (Larson et al, 2001;Moerke et al, 2004;Levell & Chang, 2008).…”