WAVE FORCING OF BEACH GROUNDWATER

Evans Waddell

Abstract


A field project was conducted to measure swash and surf characteristics and related processes on a beach with a high tide range and very low slope. Variables measured were beach waterlevels in the surf and swash zones, beach groundwater levels, and on-offshore and alongshore currents. A variety of deployment patterns and instrument combinations were used. Results show a nonlinear transfer of wave energy from high to low frequencies. This appears to have occurred because finite amplitude waves and bores caused an onshore mass flux which produced an increased local waterlevel. Periodically, this impounded water was released. Groundwater records indicate that low frequency waterlevel oscillations on the beach face were the dominant forcing function for oscillations of the beach watertable. A model is generated which adequately predicts some of the response characteristics of the groundwater table.

Keywords


wave forcing; beach groundwater; field study

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