Beach morphodynamics on the eastern Coromandel Peninsula

The study identified two different types of storm beach state on the eastern Coromandel. The two beach states were “dissipative” (fine sandy medium to large compartment beaches such as Matarangi and Pauanui) and “storm rip” (medium to coarse sand small headland bounded beaches such as Tairua and Whiritoa). These two beach types showed different modes of erosion. The storm rip beach state usually causes severe localised cut in the centre of storm rip embayments. The dissipative was seen to generally be associated with a fairly uniform cut alongshore. Some fluctuations in the amount and rate of cut on dissipative beaches may result from wave focusing. The study identified number of beach “type” profiles for eastern Coromandel beaches, as well as different modes of beach cut associated with episodic easterly storm events. The results of the study showed that a number of beach states observed didn’t fit the Wright-Short model, specifically two intermediate beach states. This work also linked bar and rip characteristics with the risk to bathers associated with each beach type. Purpose: This study investigated six eastern Coromandel beaches to assess applicability of the Wright and Short (1984) beach model and to identify interactions between sedimentological and morphodynamic variables.

Chapters: Introduction Discussion of beach state models Beaches of the eastern Coromandel Peninsula Factor analysis Hazard potential of beaches Recommendations and conclusions Mean grain size, sorting skewness, kurtosis, settling velocity reported. Mineralogical data also reported. Between two and five beach profiles are reported in the thesis Appendix for each beach. No exact dates appear to be given, but assume 1989. Various photographs, some oblique aerial, some just taken from ground (1989-1990). Thesis also includes general discussions of beach state and beach behaviour during the study, discussion of beach change in response to storms over the study period. Also basic description of each beach.

Hot Water, Tairua, Whiritoa, Matarangi and Otama Beaches

1989

Samples taken from berm, swash, surf zone at a number of sites along each beach. Number of sites = Matarangi 3, Otama 8, Hot Water 5, Tairua 2, Whiritoa 7. Sediments analysed using University of Waikato’s Rapid Sediment Analyser (RSA). Beach profile data collected using Emery method. Frequency of collection: One off.

Gaps in collection: n/a Completeness: Complete.

Photographs of different beach states. Original photographs in thesis. Digital Format: n/a

Master of Science Thesis, University of Waikato

Thesis freely available in University of Waikato library. Sensitivity/Confidentiality: No known issues.

Complete

Additional comments: Subsidiary study beaches included Rings Beach, Opito, Hahei, Pauanui, Opoutere, Onemana and Whangamata.