A COASTAL INLET WITH FIXED BED AND MOBILE SIDES

Abstract

The coastal inlet dealt with in this paper has a fixed bed of exposed rock and mobile side boundaries of sand that overlies the bed rock platform. The work was undertaken to investigate the response of the throat section to natural hydraulic and meteorological events and to observe the nature and rate of recovery of the inlet after the more extreme events. These events included sea and swell states, wind, freshwater flood flows and short term changes in mean sea level (storm surges or meteorological tides). The three year study involved the inlet at the mouth of the Barwon River, Victoria, Australia (see Figure 1). The work forms part of a continuing study to assess the impact of engineering works on the stability of the estuary and inlet, and was required to assist in delineating the natural inlet variability from that due to engineering works. The study described here looked specifically at the inlet throat section which refers to the short narrow waterway connecting the estuary with the sea. The inlet throat section at Barwon Heads is well defined and is shown in Figure 1. The inlet itself is free of training walls and is normally flanked by sandy beaches. However, the depth of the inlet is limited by a bed of rock (see Figure 2), there being, in effect, unlimited mobility on a side boundary only.