Royal HaskoningDHV prepared the Albany Artificial Surfing Reef Feasibility Study report in response to the City of Albany’s (CoA) desire to provide recreational surfing amenity at Middleton Beach, Albany, through the construction of an Artificial Surfing Reef (ASR). The ASR is to be designed to create a consistent, surfable wave, which maximises available swell conditions and is central to Albany, driving benefits in tourism, economic development and retention of Albany’s younger age demographic.
The CoA has formed the Albany Artificial Surfing Reef Steering Group (SG) to advise, engage and convey information to appropriate members of the Middleton Beach community. In addition to this, the report has undergone several peer and technical reviews.
Royal HaskoningDHV undertook the following as part of the first phase of the study:
- Analysis and review of available metocean, morphology and ecology data;
- Spectral wave modelling – To determine nearshore design wave conditions and location for the proposed ASR;
- Review of relevant literature on submerged structures and lessons learnt;
- Determination of, and reporting on, key design criteria for the construction of an ASR at Middleton Beach; and
- Design of three (3) ASR options at Middleton Beach, one of which was selected for the feasibility study (the Part B report).
Whilst Middleton Beach has a relatively low energy wave climate (mean Hs = 0.5-0.75m), the metocean analysis and subsequent spectral wave modelling illustrated that Middleton Beach possesses a number of very unique features that result in ideal conditions for the development of an ASR at this location, such as:
- A micro-tidal environment which will maximise the duration that swell will break on the reef structure;
- An almost unidirectional wave climate (modelling has demonstrated no more than a 5-10 degree direction spread);
- Relatively long period (12-16 sec) wave conditions which would result in significant wave shoaling (increase in wave height) in response to an ASR; and
- Two main areas of wave focusing; Emu Point and ‘Surfers Point’, the latter which has been identified by the City and SG as the preferred location for an ASR.
Highlighting the importance to learn from past mistakes and draw from the knowledge gained from these undertakings, a number of key parameters that drove the design process from the literature review are as follows:
- Desire to build structures from conventional engineering materials such as rock armour rather than experimental/newer technologies (such as geotextiles);
- Structures with permeable, rough surfaces (such as rock) help to reduce wave reflection, rip currents and localised scour in and around the structure; and
- In terms of surf amenity: a single-direction wave is more desirable (as opposed to an A-frame structure);
- Distance to shore, crest-depth and effective crest-width drive shoreline response in the lee of the structure (erosion/accretion) based on the most up to date research in this area; and
- Localised marine florae and faunae benefited in all instances of submerged structures investigated.
Through this process, Key Design Criteria were developed and three options were proposed for the development of an ASR at Middleton Beach, of these a preferred option was selected by the City and Steering Group; Option B providing a long (120m) surfable ‘right-hand’ wave under mean wave conditions at a distance of 180-375m from the shore.
Based on the large body of background research, case studies and numerical modelling undertaken for this study, the preferred location, layout, materials and design parameters for a potential ASR at Middleton Beach have been determined, subject to confirmation once further on-site data has been collected as part of the next stage of the project