North Stradbroke Natural Hazards and Critical Infrastructure

North Stradbroke Natural Hazards and Critical Infrastructure

Natural Hazards

Bushfire

North Stradbroke Island has a very real risk of bushfire, with the majority of the island being identified as having a high to very high bushfire risk.  There is a significant level of residential development at each of the three townships of Dunwich, Amity Point and Point Lookout that either adjoin or fall within the high to veryhigh bushfire risk areas.  Due to the steep topography of the land, potential fuel loads on the ground and the resultant bushfire behavior, the areas of greatest risk in Dunwich are along Rainbow and Illawong Crescents and the One Mile and Two Mile communities.  At Amity Point, the risk areas are to the east of the township, in behind Flinders Beach, effectively surrounding the small Flinders Beach residential community and covering the Flinders Beach camping areas for the length of Flinders Beach to Point Lookout.  At Point Lookout, areas on the inland side of East Coast Road are at greatest risk, particularly the ridgeline areas along Tramican and Donahue Streets, and across to George Nothling Drive and stretching further east to Samarinda Way.  The beach camping sites at bothFlinders Beach and Main Beach are located within large areas of high risk bushfire hazard.  These camping sites do not have mains water supply and are more isolated from services with limited access points then other parts of the island.  These issues increase the vulnerability of the camping areas which are very popular tourist destinations during the summer months.  Flinders and Main Beaches have 200 and 300 camp sites respectively which allows for a large number of visitors to be located within these areas.

Due to the high level of bushfire risk on North Stradbroke Island, a number of government agencies including RCC, QFRS and QPWS undertake coordinated hazard reduction burns and maintain fire lines to reduce the impacts of unplanned bushfires; however the inaccessibility of large areas of the island’s interior limits the extent to which hazard reduction burning can be undertaken.

Download the Amity Bushfire Prone Map.
Download the Dunwich Bushfire Prone Map.
Download the Point Lookout Bushfire Prone Map.

Flood Prone, Storm Tide

The potential for flooding on North Stradbroke Island is primarily as the result of tidal inundation that would be caused by a storm tide.  The greatest affects would be felt to the north of the island from Amity Point along the Flinders Beach areas to Point Lookout.  Current mapping indicates that during a storm tide event, the Amity Point community could possibly become isolated as the result of access roads being cut.  Flinders Beach area would also experience significant inland inundation toward the Point Lookout end, covering numerous beach camping locations along Flinders Beach and affecting the ability to evacuate from those locations as well as causing the access to Point lookout from Flinders Beach to become impassible.  Point Lookout itself may experience some inundation along Home Beach from Adder Rock, however due to the steepness of the geography at the Point; inundation would be limited to the low lying areas on the coastal side of East Coast Road.  Dunwich may experience some localised flooding resulting from tidal inundation along Flinders Avenue and Norfolk Street, affecting the Bradbury’s Beach Caravan Park and properties directly opposite.

Download the Amity Point Flood Prone, Storm Tide Overlay.
Download the Dunwich Flood Prone, Storm Tide Overlay.
Download the Point Lookout Flood Prone, Storm Tide Overlay.

Landslide

The steep sandy slopes of North Stradbroke Island lend to the island having the highest risk of landslide amongst the islands of Moreton Bay.  Whilst significant areas of high to very high risk are located in the eastern and southern bushland regions of the island away from the townships, residential development within the township areas of Dunwich and Point Lookout does have a risk of landslide.  The highest risk of land slippage at Point Lookout, on the island’s eastern coastline, has been identified around Tramican Street, Cumming Parade, Samarinda Way and East Coast Road.  In Dunwich, on the western coastline, the areas of highest risk have been identified around Rainbow Crescent and Illawong Crescent.  There is a reasonable level of residential development in these areas at the top of the ridge line along with areas at the base of the ridge line.  Mitigation strategies to reduce the affects of landslide in these areas are regulated under the Redland Planning Scheme and are based on engineering solutions at the time of the development.

Download the Amity Point Planning Scheme, Landslide Hazard Overlay.
Download the Dunwich Planning Scheme, Landslide Hazard Overlay.
Download the Point Lookout Planning Scheme, Landslide Hazard Overlay.

Critical Infrastructure

Critical infrastructure on the islands at the time of a disaster event includes utilities such as power, water, sewerage and telecommunications, and water transportation including ferry and barge services. Impacts of a disaster on these services may have far reaching long term affects for island communities.

Sewage

The sewer network operated by Redland City Council covers Coochiemudlo Island, and parts of Dunwich and Point Lookout on North Stradbroke Island.  Those parts of Dunwich and Point Lookout and Amity Point not serviced by the sewer network utilise septic systems, as does all of SMBI.

Many of the newer homes, businesses and the primary schools on Russell and Macleay Islands use modern sewerage treatment systems that require power to operate.  Therefore during extended periods of power outage the toilets are unable to be utilised or risk failure if used.  This limits the number of community buildings that can be used as evacuation centres during a disaster event.

The most serious affect of a failing sewerage system is the potential for highly infectious diseases to occur including dysentery and hepatitis.  Mosquitoes and flies that spread a number of other illnesses can breed in areas where liquid waste reaches the surface.  There are also risks to the natural environment including the health of waterways and Moreton Bay.

Water

The water supply for SMBI is piped across from North Stradbroke Island to north eastern tip of Russell Island. The supply is then piped via Karragarra Island to Lamb Island and then onto Macleay Island.  There is the ability to pipe water across to SMBI from the mainland if required and likewise, the water supply for Coochiemudlo Island is also piped directly from the mainland.  The mainland water supply is connected to the SEQ water grid and therefore the risk of the water supply failing is extremely low.  The North Stradbroke Island townships of Dunwich, Amity Point and Point Lookout source their water supplies directly from the bore fields located on North Stradbroke Island and again the risk of the water supply failing is extremely low.

Electricity

The electricity supply provided by Energex to the SMBI group and North Stradbroke Island comes via Russell Island.  The supply originates on the mainland north of Cabbage Tree Point and crosses the Western Boating Channel, connecting to the southern end of Russell Island at Rocky Point, then continues north through the centre of Russell Island before branching off to service North Stradbroke Island and Karragarra Island.  The electricity supply from Karragarra Island then connects to Macleay Island which in turn is connected to Lamb Island.

This sequence of connections highlights the importance of Russell Island to the electricity supply for SMBI and North Stradbroke Island.  A new substation has been built on Russell Island to assist in ensuring the power supply to Russell Island is more robust and with less power fluctuations.  Energex has also installed number of transformer connection points on Macleay Island which enables Energex to use generators to supply power to Macleay, Karragarra and Lamb Islands in the event of a major power failure; however this would be a reduced supply.

The main line that crosses to the southern end of Russell Island is strung on concrete poles high above the ground in a relatively inaccessible area of moderate to high bushfire risk.  If the line was impacted by bushfire, Energex would restore the line as quickly as possible given the population on SMBI and North Stradbroke Island.

The electricity supply to Coochiemudlo Island comes via an underwater line from the Victoria Point reserve at the end of Colburn Street and connects to the western tip of the island near the golf club.  The line runs underground until it meets the established road network and as such has limited impact from bushfire, tidal surge or flood hazards.

Telecommunications

Landline access to North Stradbroke Island and SMBI is via a microwave link from the mainland to exchanges on the islands. The exchanges on North Stradbroke Island are located at each of the three townships of Dunwich, Amity Point and Point Lookout and for SMBI the exchanges are located on Russell and Macleay Islands. Coochiemudlo Island is connected via a submarine cable that runs from the Victoria Point exchange to the island.

The exchanges on North Stradbroke Island and SMBI require electricity to operate and all have battery back-up systems that operate for a limited period of time.  During extended periods of power outage Telstra have generators they can be deployed from the mainland to provide additional capacity.  Telstra also have other resources such as a mobile exchange, mobile satellite coverage and mobile base station that can be deployed if required.

There is no mobile phone towers located on SMBI or Coochiemudlo Island; coverage is from towers on the mainland and North Stradbroke Island.  Mobile phone towers on North Stradbroke Island are located in each of the three townships which provide good coverage over these areas. The Amity Point tower also has a radio link to Karingal on the southern end of Moreton Island.  There are mobile coverage black spots in the southern part of North Stradbroke Island and some parts of SMBI.

Other telecommunication issues that will impact the community during periods of power outage include cordless landline phones and access to the internet both of which require power to operate.  With advancing technology, more people are utilising smart phones to access the Internet, which utilises the mobile phone network placing more pressure on the capacity of the network.

Water Transportation

North Stradbroke Island, Coochiemudlo Island and SMBI are all accessible via vehicle barge and passenger ferry, departing from Toondah Harbour, Victoria Point and Weinam Creek Marina respectively.  Along with the barge and ferry service to SMBI, Bay Island Transit (BIT) also operates the QAS boat, called Kitty Kat from the Weinam Creek Marina.  The QAS boat is available 24/7 and an arrangement is already in place to transport Energex staff to SMBI in an emergency, if Kitty Kat is not required for patient transport.

The passenger ferries are designed to operate in rough seas and therefore the size of the waves in the bay or the strength of the wind is unlikely to stop the ferries from running – high winds are more of an issue for the vehicle barges.  However, the safety of passengers as they board and depart from the passenger ferries and visibility during heavy fog or torrential rain does determine whether the passenger ferries will operate.  The passenger ferries are able to land directly onto the island’s foreshores if the jetty or pontoons were damaged or destroyed.  The main safety consideration in doing this is the loading and unloading of passengers.