CS33 Sediment-Water Interactions
Date: Wednesday, June 12, 2002
Time: 4:15:00 PM
Location: Saanich
PawlowiczR, Dept. of Earth and Ocean Sciences, University of British Columbia, Vancouver, Canada, rich@ocgy.ubc.ca
Pieters, R, , Dept. of Earth and Ocean Sciences and Dept. of Civil Engineering, University of British Columbia, Vancouver, Canada, roger@ocgy.ubc.ca
The seasonal cycle of physical structure in Harrison Lake, British Columbia is described. This deep fjord lake lies at the border of two geoclimatic zones - coastal and interior - and is influenced by both inflow with an interior hydrograph dominated by spring-summer snowmelt and by coastal rainfall. The turbid and relatively saline Lillooet River inflow dominates in summer, spreading within the thermocline and being mixed up into surface waters by wind forcing. This water slowly progresses down the lake reaching the outflow at the end of the freshet. In winter local runoff (including rainfall directly onto the lake surface) dominates the inflow. The water column is homogenized and deeper water partially renewed, but deep water temperatures remain well above the temperature of maximum density and in fact increase slightly between Nov 2000 and April 2001. Although the various input waters probably cool to near the freezing point the lake itself remains warm and monomoctic. A deep turbidity flow is seen in the northern part of the lake in one survey, with implications for water quality.