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Productive capacity of semi-alluvial streams in Ontario Researchers: Nick
Jones and Sarah Quesnelle Urbanization and climate change are expected to result in highly modified flow regimes: the result of increased imperviousness, more intense rain storms, and winter rains. These larger flows will result in the need for enhanced erosion control to prevent loss of infrastructure in urban areas. Many streams in urbanized areas have been "hardened" to protect infrastructure. In turn, recruitment of gravels into the stream may decrease do to this bank hardening and stabilization. Overall, lower inputs of sediment and increases in transport capacity will likely lead to an imbalance and the loss of gravels critical for aquatic biota and ecosystem functioning, particularly in semi-alluvial streams. We will likely see more and more clays and bedrock sections of stream. What does this mean for productive capacity? The same phenomenon frequently occurs downstream of dams where the transport of sediment is interrupted leading to reaches of river of mostly bedrock substrate. The term "hungry water" was coined by Mathias Kondolf (1997) to describe the situation. This research will compare biological productivity through sampling of fishes, benthic invertebrates, epilithon, as well as assess substrate disturbance, organic matter retention in streams with exposed clay and veneer gravels. This research will demonstrate the effects of alluvium loss on aquatic ecosystems and will help in the development of mitigation and adaptation strategies. Collaborators and
Participants: Ashmore, P.; McDonald, J.;
Burge, L.; Desloges, J.; and Ferencevic, M. 2006. Urbanization effects on
stream-flow and channel morphology in Toronto: the case of Highland Creek.
2006 Binghamton Geomorphology Symposium. October 20-22, 2006, Columbia,
South Carolina. Poster Abstract.
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