Hydrodynamics and morphodynamics of cuspated beaches on the eastern Coromandel Peninsula.

This project investigated the sedimentological, morphodynamic and hydrodynamic properties of seven cuspated beaches on the eastern Coromandel Peninsula. A range of data and analysis techniques were used to examine the interrelationships between these properties, and to investigate the formation, maintenance and spacing of beach cusps. These techniques included field data, statistical analysis, edge wave theory, surf beat, spectral analysis of current meter data and wave refraction techniques. While the beaches differed in terms of aspect, beach length, slope, sediment textural characteristics and wave climate, they all exhibited beach cusps at some time during the study. Edge wave theory was used to predict the spacing of beach cusps and a statistically significant correlation was found between the measured and predicted cusp spacing. Purpose: The aim of the investigation was to examine the hydrodynamics and morphodynamics of the nearshore zone at the beaches. This study looked at interrelationships between littoral sediment transport and distribution, wave characteristics and nearshore circulations patterns. Specifically, this study aimed to describe cusp morphology at the beaches and establish database of characteristics associated with the beaches. It investigated the temporal distribution of cusps and parameters that influence them as well as considering the theory of edge waves and whether the theory is applicable to the Coromandel beaches studied.

Chapters: 1: Introduction 2: Study location 3: Beach cusp morphological and distributional characteristics 4: Theoretical implications of edge waves for the development of a cuspated beach. 5: Morphological beach state and beach cusp occurrence 6: Nearshore wave spectra characteristics of cuspated and non-cuspated beach on the eastern Coromandel 7: Wave refraction and the spatial distribution of beach cusps 8: Conclusions

Maramaratotara, Rings Beach, Buffalo, Cooks, Wharekaho, Kuaotunu, Hahei.

All data collected in 1991-1992

Measured the nearshore velocity field at Rings and Buffalo beaches using an S4 current meter. Measured current direction and velocities 1 m above the bed. 35 min data bursts with 5 min non-recording time between. Sampled at 0.5s intervals. 4 hrs at each site. Sediment samples from horn and embayment of cusps and analysed using Waikato University Rapid Sediment Analyser (RSA). Sediment data presented in tables in thesis. Measurements of wave characteristics – visual measurements on a particular day. Measured cusp dimensions and beach slope in the field. Description and graphs of observations (by long term resident) of environmental conditions and cusp characteristics June-August 1992 at Maramaratotara Beach. Thesis includes plots of wave convergence/divergence in Mercury Bay, based on wave hindcasting. From wave refraction programme “Refraction” (Black and Healy, 1981). Frequency of collection: One off.

Exact locations not given. No figure given of sample locations.

Hard copy thesis. Digital Format: n/a

Data available in the form of hard copy thesis in University of Waikato Library. Freely available. Sensitivity/Confidentiality: None known.

Complete