Physical Modeling on Dune Erosion: Design, Instrumentation and Experimental Observations

Abstract:

The impact of extreme wave and storm surge events on coasts is expected to increase over the next several decades due to climate change. In recent years, engineers have attempted to elucidate the failure mechanisms and the morphological changes of the beach dune system, but we still lack intra-storm dune erosion data. A large-scale experimental study was designed to investigate the physics of dune erosion during a storm. The DUNE3 experiment was conducted between June 2nd and August 5th, 2019 in the Large Wave Flume (LWF), at the NSF NHERI O.H. Hinsdale Wave Research Laboratory. A coupled berm-dune profile from Mantoloking, New Jersey, USA was constructed with a 0.21 mm median diameter sediment, after applying scaling laws. The profile was tested using the highest wave and water level combinations available at the LWF, in accordance with a surge and wave event from Hurricane Sandy recorded on October 29-30, 2012. Our goal during these tests was to quantify the bed elevation changes in the inner surf zone, swash zone, and on a dune using 10 conductivity concentration profilers (CCPs), 12 ultrasonic distance meters (UDMs), 27 moisture sensors and 15 pressure sensors. These sensors were able to record time-dependent bed level elevations, uprush and backwash events in the swash, and water levels. The merits and shortcomings of the use of these sensors will be discussed in terms of their measurement precision, subsequent processing steps, and their location on the beach-dune profile.