- Title
- Quantifying the fraction of broken waves on a high energy east coast Australian beach
- Creator
- Stringari, Caio E.; Harris, Daniel L.; Power, Hannah E.
- Relation
- Australasian Coasts and Ports 2017 Conference. Australasian Coasts and Ports 2017: Working With Nature (Cairns, Qld 21-23 June, 2017) p. 429-435
- Publisher
- Engineers Australia
- Resource Type
- conference paper
- Date
- 2017
- Description
- The fraction of broken waves (Qb) is a fundamental variable in parametric wave height transformation models. It plays a key role in quantifying how much energy dissipation occurs due to wave breaking. Several authors have used different parameterisations to account for Qb; however, to the authors' knowledge, very few studies have experimentally obtained a value for the fraction of broken waves across the surf zone using field data. This paper addresses this issue by describing a methodology to quantify Qb using a combination measured pressure transducer data and remotely sensed data collected at the northern end of Seven Mile Beach, Gerroa, NSW. Pixel intensity timeseries were extracted from a timestack at the exact locations where the pressure transducers were deployed. These timeseries are compared to individual waves identified in the pressure record and the waves are classified as broken if a strong pixel peak matches a wave crest. When compared to visually identified waves, the broken wave classification algorithm was found to be correct 94.25% of the time. Results indicate that Qb is inversely proportional to water depth but highly variable at similar mean water depths. The variability in Qb showed a degree of correlation with the variation in the ratio between short (seaswell) and long (infragravity) wave energy in the inner surf zone. Probability density functions for all waves and broken waves are calculated and results indicate that wave heights in the surf zone (broken and unbroken) are not Rayleigh distributed. In fact, wave height distributions were statistically different to the Rayleigh distribution for all cases analysed, whereas they are fully described by a normal distribution in 87.65% of the cases for broken waves and in 80.25% of the cases for all waves.
- Subject
- surf zone; broken waves; remote sensing; pressure transducers; wave height distribution
- Identifier
- http://hdl.handle.net/1959.13/1396250
- Identifier
- uon:34017
- Identifier
- ISBN:9781922107916
- Language
- eng
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