HYDRAULIC PHYSICAL MODELING AND OBSERVATIONS OF A SEVERE GAP WIND

Strong gap winds in Howe Sound, British Columbia, are simulated using a small-scale physical model. Model results are presented and compared with observations recorded in Howe Sound during a severe gap wind eve nt in December 1992, Hydraulic theory is utilized to explain along-cha nnel variation in wind. Field observations affirm the findings of the physical modeling with both, indicating the presence and location of c ontrols and hydraulic jumps in the wind layer. Hydraulic behavior is f ound to change as the synoptic pressure gradient and the flow rate inc rease. In particular, field results indicate two distinct hydraulic si tuations: one during relatively weak wind, the other, which is more st rongly controlled, during the period of peak wind. An additional compa rison is made with output from the computer model hydmod of Jackson an d Steyn. Numerical simulations, configured for the conditions present in Howe Sound during the December 1992 event, indicate channel hydraul ics (and thus spatial wind speed variation) closely resembling the phy sical model and field results.