Seiches and Set-up on Lake Winnipeg
Abstract
Recorder charts of water level for the ice-free season are examined for six stations on
Lake Winnipeg for the years 1961-1964. Transverse and longitudinal seiches are identified
for the north and south basins. An interference pattern is noted for seiches over two different
fetches at Victoria Bench. Typical weather situations producing transverse and
longitudinal seiches are identified. Moderate to large set-up is examined for 37 cases and
geostrophic winds scaled off from weather charts covering an 18-hr period preceding the
peak set-up. Using corrections for curvature, motion of the pressurc system, deviation from
the main axis of the lake, and air stability, an assumned over-water component is computed
for each case. The correlation between set-up and over-water wind square is found to be
0.81. Standard deviation of actual set-up from that predicted by the regression equation
is 0.076 m.