Search

Extremes of flow and patterns of flow variability limit the distribution and abundance of riverine species via a natural disturbance regime. Using a habitat template approach, we describe the distribution and characteristics of natural flow regimes in Canada based on the severity of flows, flow predictability, and flow variability. Bayesian clustering was used to group 888 gauged watersheds across Canada into 10 classes. Some flow classes were found in all provinces, whereas others showed greater regional grouping related to land physiography (e.g., Canadian Shield and ecozones). Ontario and British Columbia had the greatest diversity of flow classes. Larger river systems tended towards less harsh flow regimes and greater flow regularity than small systems. A stream-lake network pattern, particularly the presence of lakes, decreased the severity of flow. The flow metric flood-free interval was found to be a potentially misleading indicator of reduced disturbance for high-latitude streams in Canada where ice formation and persistence are important stress factors for biota. Most flow stations had an 80% or higher chance of belonging to their primary membership class. Quantifying uncertainty in class assignment can help fellow scientists and resource managers appropriately apply our findings. [ABSTRACT FROM AUTHOR]

The characteristics of a landscape and drainage size defines the abiotic character of the stream. We advance on an existing clustering method by making it faster, more stable, capable of processing large areas, and adding several new user defined options. The software clusters interconfluence stream reaches into larger homogenous stream segments using a series of rules about network adjacency, upstream catchment area, and similarity of landscape characteristics. Landscape variables and clustering parameters are discussed to provide guidance for helping users achieve their clustering objectives. We provide an example of clustering stream reaches in Ontario, Canada that was used to develop a provincial aquatic classification. [ABSTRACT FROM AUTHOR]