The geomorphic sensitivity of rivers in the Spencer Creek watershed and its implication for watershed management in Hamilton, Ontario

The geomorphic sensitivity of rivers in the Hamilton area to land-use and climate change has not been previously examined, despite its implications for watershed management. We use three stream power-based approaches to assess the geomorphic sensitivity of rivers within the Spencer Creek watershed: (1) network-scale maps of total stream power and its changes under rural, current land-use and future climate change scenarios, (2) an equilibrium width comparison at sample reaches, and (3) a threshold grain size analysis at sample reaches. The highest total stream power for all scenarios occurred along the Niagara Escarpment, as well as through neighborhoods with high slopes and intense urbanization. The increase of total stream power between rural and current land-use is highest in the southern section of the watershed, and the future climate-change scenario indicated an amplification of these spatial patterns. The equilibrium width and threshold grain size approaches categorized most sampled reaches as sensitive, indicating a potential for erosion and geomorphic adjustment. A lack of spatial pattern among the sensitivity of sampled reaches suggests that reach-scale analyses better capture localized conditions. Examples of how stream power-based analyses at the network and reach scales can inform river monitoring and watershed management decisions are discussed.