Snowy Valleys

The LGA is vulnerable to a wide range of natural hazards, making it essential to understand the nature and extent of exposure to people, buildings, infrastructure, services, or natural resources to effectively assess and address associated risks.

Exposure can be seen in various forms:

• Relative exposure is a function of hazard, describing the frequency and magnitude of natural hazard events and capturing the compounding effect of multiple hazards (fire and flood for this analysis). Where a community is subject to both fire and flood, it is potentially less resilient than one exposed to a single hazard of the same frequency and magnitude;
• The physical exposure of a community is determined such that the quantum of exposed people, buildings, essential facilities, industry, and agriculture can be evaluated. The physical vulnerability of exposed elements is also important, such as the age and construction type of buildings (for example, buildings with raised floors are more resilient to flood as they provide greater protection to the occupants and their belongings, resulting in less loss of life and property); and
• Social vulnerability is determined by examining socio-economic and demographic factors that may exacerbate or ameliorate the effects of an external threat to a person’s life, livelihood, or assets. Examples of these types of indicators include age, occupation, health status, income and education.

The Resilience Blueprint identified the following hazards as relevant hazardous events for the southeast NSW region. In 2024 the State Disaster Mitigation Plan (SDMP) was implemented and any additional hazards or information regarding exposure of hazard in the region has been included below:

 Fire (bushfire and grassfire)

• Bush and grass fires are known to affect the Snowy Valley Region, with much of the rural areas identified as being within very high / high risk land;
• North-westerly winds accompanied by high day time temperatures with low humidity are associated with the bush fire season in the Snowy Valleys Region.
• The Snowy Valley Region has on average 66 bush fires per year, of which 4 on average can be considered to be significant; ²⁵
• Based on the potential event probability, as provided by Risk Frontiers, annual average loss of residential, commercial and industrial buildings from flood in the LGA is 14 per cent under a RCP 4.5 scenario. This accounts for a low probability of occurring but a high financial cost consequence of bushfire activity;
• In 1965, a major bushfire burnt through much of the Tumut Valley (approximately 80,000 hectares; and
• In the 2019-20 bushfire season, the Region was significantly impacted by two major bushfire events. The Dunn’s Road Fire and The Green’s Valley Fire joined to create one ‘mega’ fire. The fire burnt through 402,650ha of land over 50 days, or the equivalent of 45% of the LGA. As a result, almost 250 houses were damaged or destroyed, and nearly 800 outbuildings were also damaged or destroyed. There was also one fatality and 12 injuries (three serious and nine minor). ²⁶

Actions taken or proposed:

• Council’s Local Strategic Planning Statement (LSPS) considered risks associated with bushfires as a major issue affecting much of the Snowy Valleys Region. Planning Priority 3 of the LSPS is to ‘adapt to the impacts of hazards and climate change’.
• In the wake of the bushfires in 2020, Council has also undertaken various recovery efforts in the Region.

 Flooding

• Based on the potential event probability, as provided by Risk Frontiers, annual average loss of residential, commercial and industrial buildings from flood in the LGA is 7 per cent under a RCP 4.5 scenario. This accounts for a very low probability of occurring but a high financial cost consequence of flood activity;
• In Adelong, at the 1% AEP level of flooding under ideal flow conditions, 61 residential and 15 commercial/industrial properties would be flood affected (i.e. water has entered the allotment). The total flood damages at Adelong would amount to $0.87 Million in the event of a 1% AEP flood; ²⁷
• Major flooding has occurred in Tumut previously, arising from Mcfarlanes Creek and the Tumut River. In early-March 2012, the Tumut River reached a major flood peak of 3.7 metres and several people and horses had to be rescued. The water came from the Goobarragandra River, which had 80 millimetres of rain yesterday; ²⁸
• Major floods have occurred in the Tumbarumba area in 1891, 1903, 1905, 1931, 1960, 1974. More recently flooding has occurred in Tumbarumba:
  • In October 2010, 98 properties near Tumbarumba were evacuated as a wall of the nearby Mannus Dam threatened to collapse; ²⁹
  • In 2020, a flash flood hit Tumbarumba. Reportedly there was significant flooding around the sports field, caravan park and around Hampton Avenue; and ³⁰
  • In November 2021. As a result of November 2021 flood, a walking bridge across Tumbarumba Creek was washed away. A home also had to be evacuated. ³¹

Actions taken or proposed:

• Council’s Local Strategic Planning Statement (LSPS) considered risks associated with flooding as a major issue affecting much of the Snowy Valleys Region. Planning Priority 3 of the LSPS is to ‘adapt to the impacts of hazards and climate change’. The LSPS proposed various actions to address the risk of flooding in the Region, including: ³²
  • Action 30: Identify studies and data required to address gaps and/or limitations and improve knowledge and management of flood risk including climate change (short term and ongoing); and
  • Action 31: Undertake priority studies and management plans to address gaps in knowledge or management of flood risk and fulfil flood risk management responsibilities in accordance with the NSW Flood Prone Land Policy.
• Council have completed the Adelong Floodplain Risk Management Study and Plan – Report in 2018. The Plan also identifies several actions for Council to better improve resilience to flooding in the Adelong floodplain; and ³³
• Council has commenced preparing flood studies for Brungle, Tumut and Tumbarumba. Council undertook community consultation to obtain information on the impacts of previous flood events like March 2012, February 2019, January 2022, October 2022 and November 2022, as well as any earlier floods events. ^{34 35 36}

 Severe storm

• Severe storms in NSW are often associated with East Coast Lows (ECL). ECL events are extreme weather systems that occur in South-East Australia, bringing extreme winds, rain, hail and lightening;
• The maximum annual windspeed is projected to increase across the Snowy Valley Region in future;
• Dry lightening storms (generally occurring in late spring and summer) occur frequently and a major cause of bushfire ignition in the Region;
• On 25 November 2024, a severe storm impacted the Region leading to a natural disaster event being declared; ³⁷
• In 2021 as a result of a severe storm, torrential rain in February 2021 led to further flooding events around Adelong and Tumbarumba. June 2021 saw the largest rainfall event in a single day since 2012 which caused localised flooding in many parts of the region, in particularly on the Tumut plains; ³⁸
• Based on the potential event probability, as provided by Risk Frontiers, annual average loss of residential, commercial and industrial buildings from hail damage associated with a storm in the LGA is 54 per cent under a RCP 4.5 scenario. This accounts for a high probability of occurring and a high financial cost consequence of severe storm activity;
• Severe storms (with accompanying lightening, hail, wind snow and / or rain causing severe damage (including tornado) is identified as a likely natural hazard event in the South East Region EMPLAN; and
• In 2011, a severe hailstorm hit Batlow, an apple-growing region, leading to a disaster declaration. The storm stropped trees and damaged fruit with reported losses of 100 per cent in some of the 30 affected orchards. ³⁹

Actions taken or proposed:

• No actions have been taken or proposed to address severe storm risks by Council.

  Landslide

• Landslide can be triggered by severe weather events (e.g. heavy rainfall) or human activities (vegetation removal, overgrazing, slope modification, etc.).⁴⁰
• The probability of landslides in the region are considered rare, but the level of consequence can be high depending on the location. This risk is higher in parts of the LGA with steep topography.

Actions taken or proposed:

• No actions have been taken or proposed to address landslide risks by Council.

 Heatwave

• A heatwave is generally defined as ‘a period of abnormally hot weather lasting over several days’, and can be characterised as three or more days of high maximum and high minimum temperatures that are unusual for that location’; and ⁴¹

  Tsunami

• Tsunami’s can be generated by a number of causes, however, undersea earthquakes are the most likely to generate such an event. Tsunami waves can run up beyond the high tide mark causing significant damage to coastal areas.

Note: The Snowy Monaro Region is not exposed to this hazard, however tsunami’s are a hazard for wider South East NSW Region and may have consequential impacts to the Region.

Actions taken or proposed:

• No actions have been taken or proposed for to address storm and cyclone risks by Council within the Region.

 Earthquake

• The Canberra Region sits on a major eastern fault line. The nearest seismic zone is to the north near the township of Gunning. On 15 February 1998, a magnitude ML 4.2 earthquake occurred in the Brindabella Mountains, near Brindabella Homestead (in the north east of the Region), this earthquake was large enough that it was felt in Cooma; and ⁴²
• Based on the potential event probability, as provided by Risk Frontiers, annual average loss of residential, commercial and industrial buildings from flood in the LGA is 13 per cent under a RCP 4.5 scenario. This accounts for a low probability of occurring but a high financial cost consequence of earthquake activity.

Actions taken or proposed:

• No actions have been taken or proposed for to address risks arising from an earthquake by Council within the region.