Effect of Cold Front-Induced Waves Along Wetlands Boundaries
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AbstractAlong wetland shorelines, the energetic wave environment generated by cold fronts occurs more frequently than for major storms, yet their impact on wetland evolution processes has not been fully identified. To capture the changes in wave climate during the passage of cold fronts, a wave gauge was installed near a salt marsh edge in Galveston Bay, Texas, USA. A coupled wavehydrodynamic model, validated with the data, was used to assess the dominant processes of cold front induced surge and waves. During the measurement period, wind gusts and abrupt direction shifts during cold fronts produced highenergy wave events that propagated toward the wetland edge. Before a cold front passed our study area, there was an initial increase in the water level inside the bay. As soon as the cold front passed and the wind direction shifted, large waves were created by strong winds. Over the first few hours, the relatively high water level reduced the depth limitations on these waves, allowing them to be quite large. However, as the waves struck the wetland edge at these higher water levels, vegetation intercepted and dampened the erosive force. Over the next few days, the water level dropped well below the mean tide, allowing plunging waves to impinge directly on the edge with a highenergy flux. From the calculated wave power during the entire measurement period, it was found that cold frontinduced waves, despite their brief duration, had a high erosive impact on the evolution of the wetland edge.
