Presaging Beach Renourishment from a Nearshore Dredge Dump Mound, Mt. Maunganui Beach, New Zealand
Keywords:Ebb delta beach, erosion, accretion, sediment tracing, beach profiles
A study was undertaken to ascertain whether material to bedredged from theshipping channel through a large ebb tidal delta at the entrance to Tauranga Harbor, New Zealand, could be dumped in shallow water (5-8 m below Mean Sea Level) off the downdrift Mt. Maunganui Beach and induce beach nourishment. Investigations included comparison of sedimentological texture of the material to be dredged, the dump site on the beach; a fluorescent sediment tracing experiment; application of standard Shore Protection Manual "fill" and "renourishment" factors; and application of the new techniques of KRAUS et al. (1991), and HANDS and ALLISON (1991).
Results illustrated textural similarity between the sediments to be dredged and the natural beach and dump zone, while the sediment tracing experiment indicated predominantly onshore movement. Application of the S.P.M. techniques along with the new techniques of Kraus et al. (1991) and HANDS and ALLISON (1991) gave consistent, plausible indications that beach nourishment would succeed from the nearshore dumping. This was confirmed by sequential beach and bathymetric surveys subsequent to dumping.