Coastal Restoration Trust of New Zealand

Coastal Dune Ecosystem Reference Database

Seawalls versus Beaches Journal Paper

Pilkey, O.H. &; Wright, L.W.
Journal / Source
Publisher / Organisation
Journal of Coastal Research
Beaches, Shorelines, Coastal engineering, Storms, Sand, Erosion, Barrier islands, Dunes, Armoring, Breakwaters
Not a NZ publication It is widely assumed that hard shore-parallel structures on the beach are damaging to recreational beaches. Virtually all state coastal management programs assume this to be true. While there is broad agreement that walls are detrimental to adjacent beaches and that walls are passively responsible for narrowing of the beaches in front of them, controversy still remains over the question of whether seawalls play an active role in beach degradation. Coastal management initiatives should not be delayed on account of the technical argument regarding seawall behavior. From the standpoint of the general public, the important question is whether seawalls negatively impact beaches, rather than exactly how it happens. It is argued in this paper that there are a number of mechanisms by which seawalls can accelerate erosion of the beach in front of them and that, until research proves otherwise, active beach degradation remains a real possibility. In this investigation, we have also compared the dry beach width on selected stabilized and unstabilized East Coast shorelines and note that dry beach width is consistently and significantly narrower in front of walls. The more dense the hard stabilization, the narrower the beach. Future research on seawall effects must take into account the fact that beach destruction may take place over several decades and study of single events or short-term changes may be of limited value in understanding effects of seawalls.
Not available electronically