Flood evacuation route improvements - State guideline

The Guideline outlines an options assessment process to support the identification of ‘fair and reasonable’ flood evacuation route improvements to inform decision making. The Guideline may be used to inform flood risk management activities particularly when identifying and assessing options.

The Guideline is a statewide non-mandatory guideline developed to consider different flood risk profiles (flooding types, size, severity, duration and exposure) and support flexible implementation of options by entities who vary in resource capability and funding capacity.

The Brisbane River Strategic Floodplain Management Plan (BRSFMP) represents the third phase of the Brisbane River Catchment Flood Study, which was developed in response to recommendations from the Queensland Flood Commission of Inquiry. The Plan identified the need to develop state guidelines to support the identification of ‘fair and reasonable’ flood immunity for evacuation routes. This Guideline and supporting materials deliver on this identified need which is referred to as BRSFMP Action FM12.3.

Users of the Guideline may include local governments, state agencies and Queensland’s disaster management groups, supported as needed by suitably qualified or experienced persons. This recognises that the governance of flood risk management in Queensland is based on a collaborative, decentralised model with shared roles and responsibilities. Please see the Queensland Flood Risk Management Framework for further guidance on roles and governance.

The Guideline undertakes a broad approach to the BRSFMP Action FM12.3 by supporting the identification of 'fair and reasonable' flood evacuation route improvements. This includes a range of options beyond improvements to the flood immunity of evacuation routes such as flood warning systems, evacuation centres, road upgrades to improve capacity or resilience, new roads, and levees. This approach ensures that cost effective options, which may achieve similar outcomes to larger infrastructure projects, are included.

This Guideline does not provide guidance, or a recommended process, for:

• evacuation capability assessments (ECAs)
• economic assessments of flood risk management projects 
• evacuation planning.

The Guideline may be applied to new development; however, this is not the intended purpose and specific guidance has not been provided. The Guideline does not address flooding as a result of dam failure. Please refer to the Guideline for failure impact assessment of water dams (external link) for further information.

The identification and assessment of evacuation route improvements involving new or upgraded road infrastructure requires coordination with road infrastructure stakeholders. Facilitating engagement with these stakeholders is important as they often operate under different processes and/or in separate organisations to floodplain management processes. Road infrastructure stakeholders provide valuable input on the practicalities of road infrastructure options when assessing and identifying evacuation route improvements.

Evacuation planning is the development of plans or arrangements to co-ordinate and execute evacuation, if required, when a flood event occurs. Evacuation plans or arrangements are developed based on existing measures and infrastructure, such as existing evacuation centres and routes.

In contrast, the identification of evacuation route improvements is a process of identifying new or improved infrastructure or measures to improve evacuation capability and resolve evacuation constraints. Evacuation plans and the identification of evacuation route improvements are undertaken separately. However, evacuation plans may need to be revised to consider changes to evacuation planning resulting from evacuation route improvements.

The options assessment process outlined in the Guideline is one method to assess and compare options against assessment criteria. The assessment process is a multi-stage decision support tool for the identification of 'fair and reasonable' flood evacuation route improvements by providing information on the effectiveness and efficiency of options based on their benefits, impacts, cost and constraints. Following stakeholder identification and data collation, options are identified and assessed using the following process (Guideline p5):

• Understand the evacuation problem – evacuation issues are investigated before defining the evacuation problem, service need and desired outcomes
• Identify potential options – identify a long list of options which are fit for purpose to local circumstances
• Options assessment – options are assessed through the following stages:
  • Stage one: Option feasibility assessment – high level assessment of all relevant potential options to eliminate options that are not practical or feasible to create a short list of options
  • Stage two: Multi-criteria assessment – detailed assessment of short-listed options against criteria and targeted indicators
  • Financial and economic assessment of short-listed options
• Review outcomes – assessment outcomes are reviewed to identify a preferred option or a combination of options.

Where no options are suitable or further refinement is required, options can be redefined or further information collated before revisiting the assessment process.

Users will need to follow each stage of the assessment process to identify and assess evacuation route improvement options. The Guideline provides for flexibility in the level (availability and quality) of data required to inform the assessment process. The level of detail required for each assessment depends on the evacuation problem, the scale and the type of options being assessed.

Prior to undertaking the assessment process, users collate data to inform the assessment process. Data can be collated from a number of resources including flood studies, flood risk assessments, evacuation capability assessments, records of historic floods and through stakeholder and community engagement.

The availability and quality of data to inform the assessment process may vary between users. Reduced quality or availability of data may affect confidence in the assessment results. If sufficient confidence in the assessment process cannot be achieved with available data, it may be necessary to collect additional data.

Further information may need to be collated to assess options during the assessment process. For example, ecological assessments may be required for the detailed assessment of options which may result in impacts to vegetation and habitat.

Throughout the assessment process users will need to determine if further studies are required to inform the assessment process.

The level (availability and quality) of data to inform the assessment process at each stage should be fit-for-purpose to the evacuation problem, scale and type of options being assessed.

Weightings are applied to the multi-criteria assessment criteria to capture the relative importance of each contributing decision factor and issue to decision makers. Sensitivity testing is applied to assess the robustness of the final rankings against the assigned weightings. Various methods of sensitivity testing can be applied to the multi-criteria assessment to detect bias towards particular options and to enable a balanced comparison of options.

If a clear preferred option or options cannot be identified, options can be refined, or further information collated before revisiting the assessment process.

Further approvals and agreements may need to be obtained and the scheduling of the project may be dependent on the priorities of the organisation responsible for delivery.

Once an option is ready to be considered for investment the implementation process commences. The implementation process is influenced by local policies, practices and processes; however, it typically follows the steps described below:

• business case: development of a business case to identify the merit of the option and seek funding
• implementation plan: development of a roadmap to implement the option
• implementation: delivery of the option.

Identifying and engaging with stakeholders is critical to the assessment process, as stakeholders can provide valuable local knowledge and expertise when investigating the evacuation problem and identifying and assessing options.

It is intended that stakeholders who have a responsibility or consequence in relation to resourcing, implementation or delivery of potential options are engaged throughout the process. Engaging with these stakeholders ensures policies, planning, and funding requirements related to an option’s delivery are considered. Failing to engage with stakeholders may result in difficulties implementing preferred options.

Engaging with stakeholders ensures that:

• the practicality and/or impacts of potential options are identified
• preferred options align with other floodplain management measures and forward-planning for infrastructure and future development
• potential issues are identified early, avoiding unnecessary rework
• changes or opportunities due to new information are communicated
• funding sources to deliver an option can be identified.

Users should have early and ongoing engagement with stakeholders throughout the assessment process, particularly with stakeholders who have a responsibility or consequence in relation to resourcing, implementation or delivery of potential options. Potential stakeholders include local governments, state agencies, large land holders, significant private entities or community groups. State agency stakeholders include those with disaster management roles, affected government landowners, and evacuation infrastructure providers. A list of potential stakeholders is provided is Table 2 of the Guideline.

Community consultation is an integral part of the assessment process as effective evacuation requires community acceptance and a willingness to cooperate and respond in an emergency. Understanding the community's vulnerability, resilience and tolerability to the effects of flooding ensures that selected improvement options are fit for purpose to the needs of the community.