FAQs

A flood study and a flood risk management study and plan are 2 separate processes

Flood study – A flood study is a technical engineering report that identifies how flooding behaves within a catchment area. Using models, the study simulates how floodwaters move through the region. The results of the flood study show how, when and where flooding will affect the community.

Flood risk management study and plan – The flood risk management study and plan come after the flood study. It uses the results from the flood study (the how, when and where of flooding) to identify and assess different management measures to reduce the impact of flooding on the community.

Flooding is the most expensive natural disaster in Australia, with an average cost of $8.8 billion per year (Deloitte 2017). The impact of floods depends on factors like rainfall intensity, frequency and duration, as well as the characteristics of the land and the vulnerability of both ecosystems and societies.

According to the NSW Government Flood Prone Land Policy, local governments are responsible for managing flood liable land.

We are currently in the early stages of gathering data and conducting a flood study. This will help us better understand the existing flooding issues in the catchments.

Once this phase is complete, we will develop a Flood Risk Management Study and Plan. This next phase will explore various ways to manage flood risk, such as structural solutions and planning controls. To ensure the best possible options are considered, the study will use the most up-to-date information on flooding in the catchments.

The previous flood study, completed in 2009, is being updated to incorporate new data and modelling techniques in line with current industry practice. The new flood study will improve our understanding of flood behaviour within the coastal creeks catchment and the results of the flood study will be more closely aligned with ‘real world’ flooding.

This study will follow the NSW Government Flood Prone Land Policy, which outlines a staged process involving data collection, a flood study, a floodplain risk management study and plan and the implementation of the plan.

The stages of the project are as follows:

• Collect and review all available flood-related information and data for the area.
• Develop and calibrate a computer flood model using historic flood events to simulate flood behaviour within the catchment.
• Simulate a range of hypothetical flood events, from common storms to the worst-case flood scenario.
• Examine and recommend management measures, identifying and assessing the risks to the community and evaluating different options to manage those risks.
• Develop a plan to ensure Council can effectively manage flood risk in the study area now and in the future, for the benefit of the community.

The coastal creeks region has various landscapes including steep channelised valleys, floodplains and coastal estuaries. This leads to 3 main types of flooding:

• Riverine flooding: when water overflows from rivers or creeks.
• Storm surge flooding: when sea levels rise unusually high due to storms.
• Overland stormwater flooding:  when rainwater runs off and flows toward drainage systems or creeks.

A flood risk management study and plan focuses on managing flood risk through both structural and non-structural measures.

Structural mitigation measures involve physical changes to the environment such as building levees, floodgates or upgrading the stormwater network.

Non-structural mitigation measures reduce flood risk through planning controls. These can include adjustments to land use policies, relocating residents and implementing early warning systems.

Flood insurance terms, conditions and premiums are set by the insurance industry. Insurers may base property assessments on Council’s flood information however, Council has no influence over flood insurance products or premiums.

See Insurance Council of Australia and Understanding insurance for more information.

WMAwater, a recognised expert in flood and water management, was engaged by Council to help update the Tweed Coastal Creeks Floodplain Risk Management Study and Plan. They specialise in hydrological and hydraulic studies of waterways and floodplains and the development of long term strategies and designs for management of flood and water resource risks.