A long-term coastal monitoring programme has been undertaken by the City of Wanneroo since 2014. The purpose of the programme is to assess changes to the City’s coastline and to document the condition of the City’s coastal structures. This helps to better inform coastal management measures, identify key areas requiring future management, provide data for future coastal hazard studies and identify maintenance requirements.
The coastal monitoring programme involves the collection and assessment of the following data.
Monitoring of coastal structures every six months
Every six months the City undertakes photographic monitoring of the City’s coastal infrastructure assets. This is used to capture a photographic record of the assets, identify and address any public safety and maintenance requirements and to flag any major concerns that may require further detailed investigation.
Manual images of vulnerable beach sites taken every six months
Photographic monitoring is undertaken every six months at 57 vulnerable beach sites along the City’s coastline. This assists with understanding the seasonal and long-term changes in vulnerable areas of the coastline. An example of significant seasonal changes at Quinns Beach is provided below. Inspections of the City’s vulnerable beaches are also undertaken following extreme storm events in order to capture a record of storm damage and address any immediate safety concerns or maintenance requirements.
|Quinns Beach - March 2020||Quinns Beach - October 2020|
|Significant seasonal erosion is apparent over the 2020 winter period at Quinns Beach. There is a wide, usable beach after the summer months (in March) and a very narrow beach following winter months (in October).|
LiDAR aerial surveys
LiDAR surveys are undertaken in April and October each year by aerial survey contractor McMullen Nolan Group Pty Ltd. The survey covers the entire City of Wanneroo coastline and analysis is performed after each survey to assess annual and seasonal changes in beach volumes.
April 2021 LiDAR survey of Yanchep coastline
Remote coastal monitoring cameras
The City will install five remote coastal monitoring cameras along the coastline towards the end of 2021. These remote coastal monitoring cameras will capture still images of the coastline hourly at the locations depicted in the below maps.
|Planned remote monitoring camera locations at Quinns Beach||Planned remote monitoring camera locations at Yanchep Lagoon|
The images that are gathered allow for the hourly assessment of coastline changes at these vulnerable locations. These images will be assessed visually and via a program that detects shoreline changes.
The City has recently incorporated the assessment of satellite and aerial imagery into the coastal monitoring programme. Satellite and aerial imagery is taken every one to two months and covers the City’s entire coastline. By assessing satellite and aerial imagery the City is able to analyse changes to the coastline more frequently than LiDAR surveys or manual imagery.
Metocean data including waves and water levels are also assessed as part of the coastal monitoring programme. This data assists with the interpretation of changes identified in photographic records and analyses of survey data. Data is obtained from the following instrumentation managed by the Department of Transport (DoT):
- Half-hourly wave data from the DoT Rottnest Island Wave Station; and
- 5-minute water level data from the DoT Fremantle Fishing Boat Harbour Tide Station.
Annual detailed condition assessment of the City’s coastal protection structures
In October each year the City undertakes detailed condition assessments of the City’s coastal protection structures. Condition assessments are undertaken to identify any structural damage caused by winter storm and erosion events. The following coastal protection structures are assessed:
- Artificial rock headland at Quinns Beach;
- Groynes 1 to 4 at Quinns Beach;
- Rock and sandbag revetments at Quinns Beach;
- Mindarie Breakwater and spur groyne; and
- Capricorn groyne at Yanchep Beach.
Should you have any queries in relation to the City’s Coastal Monitoring Programme please contact the City’s Coastal Engineer, Sarah McCulloch, on 9405 5000.