Barrier dynamics experiment (BARDEX): Aims, design and procedures

Abstract

Although relatively common features in nature, only a handful of laboratory studies have examined the dynamic response of gravel beaches and barriers to combined tidal and wave forcing and to storm simulations. This paper reports experiments undertaken in the Delta flume during the BARDEX project using a prototype gravel barrier (55m-long, 5m-wide and 4m-high with seaward and lagoon facing slopes of 1V/8H and 1V/4H, respectively) composed of sub-rounded gravel (D50=11mm). Hydrodynamic conditions and beach morphology were measured using buried PTs, ECMs and closely spaced bed location sensors on a scaffold frame spanning the entire barrier. Additional measurements were also obtained from video and 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 (hL) sides of the barrier. These included: 1) hydraulic conductivity tests where hS and hL levels were varied; 2) tests to assess the impact of waves (hS=2.5m, variable hL in the range 1m to 2.5m, significant wave height, Hs=0.8m, and peak wave period, Tp=3.0s, 4.5s and 6s); 3) tests examining the effect of tides (varying hS from 1.75m to 3.25m, variable hL at high (hL=hS+1m), medium (hL=hS) and low (hL=hS−1m) levels, Hs=0.8m and Tp=4.5s); and 4) overwash tests (tidal simulation, variable hL, Hs=1m and Tp=4.5s, 6s, 7s and 8s). The principal objective of the paper is to provide essential information on the design and execution of the BARDEX experiments referred to in the series of papers that follow in this special edition. It also describes the instrumentation used to measure hydrodynamic, morphodynamic and sediment processes.