BARDEX (Barrier Dynamics Experiment): Taking the Beach into the Laboratory

Abstract

Although relatively common features, few laboratory studies have examined the dynamic response of gravel beaches and barriers to both tides and waves. To address this a prototype gravel barrier (5 m wide and 4 m high with seaward and lagoon facing slopes of 1:8 and 1:4) composed of sub-rounded gravel ( D50=10 mm) has been studied in the Delta flume. Detailed hydrodynamics and beach morphology were measured using video, buried PTs, ECMs and closely spaced bed location sensors on a scaffold frame spanning the entire barrier. Additional<br/>measurements were obtained from instruments on an offshore frame. A series of systematic tests were undertaken using pumps to change water levels on the seaward (hs) and lagoon (hj) sides of the barrier. These included: 1) hydraulic conductivity tests (hs and hj levels were varied); 2) tests to assess the impact of waves (hs= 2.5 m with variable hj and waves of lm and periods 5-7 s; 3) tests examining the effect of tides (tidal simulation by varying hs from 1.75 m to 3.25 m with hi at high, medium and low levels and 1 m random and regular waves with periods 3 s, 5 s and 7 s); and 4) overwash tests (tidal simulation with variable hi and random waves of height ca. 1 m and periods 4.5s, 6s, 7s and 8s). This paper is intended primarily to make the community aware of the experiments and to describe the objectives and methods used.