February 11, 2014: Guest Lecture
Brett Eaton

12:30pm to 1:20pm, AERL Theatre (room 120)

The AERL building (Aquatic Ecosystems Research Laboratory) is located on 2202 Main Mall at UBC Vancouver.

 

Modelling interactions between riparian forests and fish habitat in mountainous watersheds

ABSTRACT: Stream networks in the Pacific Northwest are particularly good examples of fluvial systems that are controlled by a range of biophysical interactions. Forests adjacent to such streams reinforce the channel banks, thereby affecting the channel shape, bed material transport capacity and degree of lateral activity. They also supply wood to the stream, which interacts with the channel by storing and releasing sediment, and by altering the frequency and character of pools, bars and riffles. Where wood is small enough to be transported by the stream but large enough to span the channel at some locations, jams can form that alter the channel pattern by triggering avulsions around the jams. These biophysical interactions strongly influence the quantity and quality of the physical habitat available for certain species of fish, particularly salmonids. Furthermore, they are strongly scale dependent, and the interactions (and thus habitat) characteristic of smaller channels are quite different from those typical in larger ones. These channels are also influenced (to varying degrees, depending on their scale) by disturbances to the riparian forest such as wildfire. We have developed a stochastic model to investigate how wood, sediment transport and habitat character interact across a range of channel scales. The model is based on physical representations of the wood input and movement processes, and empirical relations from a set of flume experiments relating wood size and orientation to sediment accumulation, and we use it to run Monte Carlo simulations that describe the distribution of possible channel states for channels of different scale. We also use the model to investigate the response to and recovery from (in terms of physical habitat) disturbance by wildfire.

Brett Eaton’s PowerPoint Presentation