Hydraulic geometry: Looking at an old concept in new ways

Sponsored by CEREO

John Petrie, PhD
Assistant Professor, Civil and Environmental Engineering,  WSU-Pullman

Throughout history, humans have relied on rivers for a variety of uses including transportation, food, water for drinking and irrigation, renewable energy, and recreation. River channels also form the physical basis for riparian ecosystems with flow and sediment processes in the channel coevolving with flora and fauna. This process often leads to a state of dynamic equilibrium where the channel is essentially stable in form. Both anthropogenic activities and natural events may alter flow and sediment dynamics in the channel, disrupting this equilibrium. Disruptions may be due to direct or indirect impacts and often have significant environmental effects. Direct impacts occur within the channel and include channelization, instream structures, and gravel mining. Indirect impacts occur outside of the channel and alter the magnitude and timing of water and sediment delivery to streams. Examples of indirect impacts include changes in land use or climate. Hydraulic geometry, or regime equations, is a tool to relate hydrologic variables to channel form. While this concept is more than 50 years old, regional regime equations now form the basis of many stream restoration projects. This presentation revisits the concept of hydraulic geometry and investigates new applications. Using example data, it is demonstrated how hydraulic geometry clarifies the physics underlying fluvial processes as well as predicts generalized changes in channel form.

Wednesday April 8th, 2-3 pm,  Lighty 405