POL has recently been examining the optimisation of shallow water tidal models using a 2D 4km model of the Bristol Channel. Sensitivity of the results to adjustments in the coefficient of bottom friction, water depth and grid scales were investigated. The mutual influence of tidal constituents in the presence of non-linear bottom stress is considerable and complex in nature but can be estimated. It was concluded that, to achieve good accuracy when a limited set of harmonic constituents is included in tidal model simulations, a spatially variable drag coefficient will generally be required.
Comparison between observed surge elevations (in blue) at Liverpool with results from model calculations. Click on the image to download the full image (33KB).
a) resolution 14km (1979)
b) resolution 7km (1992)
c) 1km without wave effects
d) 1km with influence of a representative wave field appropriate to the surge peak, (11/12 Nov 1994)
