Strategic Flood Risk Management

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1 Strategic Management Duncan McLuckie (NSW Department of Infrastructure and Natural Resources) Introduction This paper discusses what is meant by strategic flood risk management, who is responsible in New South Wales, what the objectives are and how can these be achieved and the associated benefits. It outlines the essential role land use planning has in managing flood risk strategically. What does Strategic Management mean? There is a strong emphasis in the NSW Government s Floodplain Management Manual (the Manual) on strategic management of flood risk. However, this term is not defined. The following definition is put forward based upon its contextual use and considering the additional points outlined below. Strategic flood risk management is the control of the impacts of the full range of flood risk on people and property within a long term planning and policy framework to meet relevant council standards, appropriate community expectations and accepted environmental management practices. The Manual also outlines the floodplain risk management process, shown in Figure 1 and highlights the need to manage the full range of flood risk, including extreme events. It also indicates that flood risk in NSW needs to consider both riverine and local overland flooding. In addition to the Manual the definition of strategic flood risk management considers: the NSW Government s Flood Prone Land Policy (the Policy). The prime objective of which is to reduce the impact of flooding and flood liability on individual owners and occupiers of flood prone property, and to reduce the private and public losses resulting from floods, utilising ecologically positive methods wherever possible. The Policy also indicates that local government has prime responsibility for management of flood prone land, are responsible for setting appropriate development standards and formulating and implementing management plans. It indicates that the State Government provides councils with: technical assistance through agencies including Department of Infrastructure, and Natural Resources (DIPNR) and State Emergency Service (SES). The SES is also identified in the State Emergency Service Act 1989 as the States flood combat agency. financial assistance through floodplain management funding programs managed by DIPNR. limited protection for them and their staff against claims for damages resulting for issuing advice or granting approvals on flood risk providing they act in accordance with the principles and guidelines of the Manual. that floodplain risk management committees are made up of representatives from council (staff and elected), statutory authorities (in an advisory capacity), and the community (business and environmental groups and the flood-affected residents). They are therefore primarily based in council and the community and would be expected to reflect the desires of the community within the framework of council s statutory and duty of care responsibilities. Strategic Management 1

2 Floodplain Risk Management Committee Established by council. Must include community groups & state agency specialists Data Collection Compilation of existing & additional data. Flood Study Defines the nature & extent of the flood problem, in a technical form. Floodplain Risk Management Study Assesses management options considering social, environmental & economic factors relating to risk. Floodplain Risk Management Plan Management plan for flood risk approved by the council after public exhibition. Figure 1 The New South Wales Floodplain Risk Management Process Plan Implementation Flood, response and property modification measures including works, planning controls, flood warnings & response plans. How can be Managed Strategically? Considering this definition, managing flood risk strategically requires the following steps, which are divided into there location in the floodplain risk management process overseen by a committee whose makeup is outlined above. This process is most effective with appropriate community consultation throughout, to gather flood data, to inform the community of the objectives, to understand the options they may feel are relevant, and to gauge their opinions on options. Scoping the Flood Study and Data Collection Define the flood problem that needs investigation Data Collection and Flood Study Understanding the full range of flood behaviour Scoping the Floodplain Risk Management Study identify the issues relevant to the particular situation; determine the objectives in managing each issue; Floodplain Risk Management Study identify and analyse the management options available for meeting the objectives; determine the most appropriate set of management options for the particular situation; Floodplain Risk Management Plan adopt the desired set of options into a management plan; and Implementation implement the adopted management plan. These steps are discussed below. Scoping Data Collection and the Flood Study Define the Flood Problem that needs Investigation Before starting an effective and focussed investigation of flood behaviour it is essential to consider the actual study area to ensure that the full flood situation that may be impacting upon the community is addressed. This involves considering whether the problem is from a local catchment, a river, or a combination of both, whether it covers the full area of interest, including future development areas, and whether there are any potential significant impacts external to an area that may need to be considered, such as: Strategic Management 2

3 the influence of another river or the ocean on flood behaviour; changes in the floodplain another local government area; and the potential for flows from another catchment to affect flooding. Considering these issues will help ensure that the study is broad enough to define the flood problem, to allow effective assessment of a range of potential management issues and options, and is more likely to effectively engage the community, as it is addressing the problems that they are concerned about. Data Collection and Flood Study Understanding the Full Range of Flood Behaviour Once the flood problem to be addressed has been identified it is then a matter of studying its behaviour for the defined area and scope for the full range of events up to an extreme events, such as the probable maximum flood (PMF). This is undertaken in a flood study which: collects the full range of necessary historical and catchment data; considers historical flood behaviour and topography of the catchment and the floodplain and uses this as the basis of developing a model of flood behaviour; models flood behaviour for events within and beyond the limits of our experience up to the PMF; considers the impacts of the full range of flooding on both existing development and areas of potential new development in the study area; and could be extended to undertake a preliminary assessment of flood hazard and damages to help identify particular problem areas so that these can be targeted in management studies. A well-scoped and executed flood study provides us with the necessary understanding of flood behaviour and provides a robust basis for considering management options. Scoping the Floodplain Risk Management Study Identify the Issues that Need Consideration Once we have a good understanding of the full range of flood behaviour it is important to examine the issues that need to be considered as part of strategic management of flood risk. These go beyond the central and critical examination of danger to personal safety and damage to property, and should include the issues identified in Table 1. Whilst these other issues are generally of lesser importance than personal safety and property damage, they still need consideration as they may be: Essential to emergency management and therefore safety during a flood. For instance, critical infrastructure, such as, evacuation routes, evacuation centres, emergency response headquarters, hospitals, and perhaps critical portions of utility services. Without considering these facilities, management of the disastrous consequences of flooding and associated recovery may be hampered, made extremely difficult or significantly extended. The impacts on society are often overlooked. One of particular importance is the viability of a whole township, due to flood impacts. This can be a particular issue if the majority of the town is inundated for extended periods, making normal life impossible, as would occur in some western townships in NSW without their protective levees. The business sector can also be significantly affected, and its viability reduced by extended Strategic Management 3

4 flooding. It is important to try to enable reactivation of the normal business cycle within townships as soon as possible after flooding. The forgotten cost of flooding. Damage to public infrastructure tends to be overlooked in studies as these focus on direct residential and commercial damages. However, the cost may be significant and, depending upon the scale of the damages, the State and Commonwealth Governments provide significant assistance under natural disaster relief arrangements. Design of future infrastructure or replacement or upgrading or existing infrastructure (as part of their normal replacement cycles) with due consideration of flood risk would significantly reduce the long term damage and associated rectification costs by providing more flood resilient infrastructure. Areas of important habitat, such as flood dependent ecosystems, may be affected by past, current and future management decisions. They should be considered in decision making with emphasis given to considering protection or perhaps rehabilitation as part of works. Other natural hazards or trends, which will impact upon flood issues need to be considered for compatibility with flood risk management. Natural hazards which are likely to impact upon flooding issues include: coastal hazards and associated wave run up which induces higher flood levels; potential coastal and estuarine recession needs consideration as they impact upon on decision making on whether to and, if appropriate, how to develop foreshore areas which may also be flood prone; and long term geomorphology of the river. If significant movement of the river, by further meandering is likely, this needs to be considered in examining flood risk management measures and development limits to ensure that these are appropriate for the long term conditions. Management of other environmental issues may have a significant impact on flooding and therefore needs consideration to ensure that management decisions, approaches and assumptions are compatible. Water quality Initiatives such as stormwater management plans, may result in significant impacts upon flood risk, particularly where these plans require works or significant revegetation of the main flowpaths or floodways. Any such potential measures need to be considered when determining design flood levels and in developing flood risk management options to ensure compatibility of assumptions with likely long-term conditions. The issues that are critical, and their relevant importance, will depend upon the individual situation and therefore need to be reviewed and considered for each individual project. Determining the Objectives for Each Issue To determine the objective for each flood risk issue we first need to consider the full range of flood risk, which includes: existing flood risk: the risk an existing community is exposed to due to flooding. future flood risk: the risk new development would be exposed to due to flooding. continuing (or residual) flood risk: the risk a community is exposed to after flood risk management measures have been implemented. For example: the consequences of a levee overtopping; or of houses built to appropriate development conditions (minimum floor levels); flooding in events larger than the design standard. Strategic Management 4

5 This is the risk that it may not be socially, practically, environmentally or economically feasible to manage through works, such as higher levees, in existing development areas or higher minimum floor or fill levels in new development areas. Continuing flood risk exists in both existing and new development areas and needs to be considered in managing risks in these areas, as highlighted in Table 1. Given this, the objectives for both new development and existing development areas can be seen as practically identical. However, the ability to and methods used to achieve these objectives differ. The objectives for each issue are as follows: danger to personal safety aims to enable people to be safe by minimising the danger they are exposed to due to flooding. damage to private property is to be managed by providing protection to an acceptable level and considering recovery from events, which overwhelm protection, by either works or development controls. critical infrastructure needs to be available and suitable to perform its critical functions, within reasonable limits, during, or in the aftermath of, flooding to aid emergency response and recovery. societal implications due to flooding need to be considered in management. Protection may be provided to a certain scale of event with township viability, and ability to recover, considered in larger scale events. public infrastructure needs to be designed and constructed, or upgraded as part of its normal life cycle, or rebuilt after damage, considering the potential impacts of flooding to reduce future damage, where cost effective. flood dependant ecosystems need to be considered in decisions. This may mean that they are protected, or restored or enhanced in conjunction with management works or protected in new development areas. management of other natural hazards need to be considered for compatibility with flood risk management, and for potential joint impacts, where applicable. management of environmental issues need to be considered for compatibility with the management of flood risk. Table 1 Objectives for Strategic Issues Existing Developed Areas New and Redevelopment Areas Existing Continuing Future Flood Risk Continuing Danger to Personal Safety Safety Safety Property Damage Protection Recovery Protection Recovery Critical Infrastructure Availability & Suitability Availability & Suitability Flood Dependant Ecosystems Protection, restoration or Protection enhancement Societal Implications Consider Consider Other Natural Hazards Compatibility, consider Joint Impacts Compatibility, consider Joint Impacts Other Environmental Issues Compatibility Compatibility Strategic Management 5

6 Floodplain Risk Management Study Identify and Analyse the Management Options Available for Meeting the Objectives Management of the full range of flood risk to both existing and future development for the range of issues outlined in Table 1 requires a suite of management options. Typical flood risk management measures are outlined in Table 2. Property Modification Measures Zoning and development control House raising Flood proofing of buildings Voluntary purchase Flood access Table 2 Typical Management Measures Response Modification Measures Community awareness Community readiness Flood prediction and warning Local flood plans Evacuation arrangements Recovery Plans Flood Modification Measures Flood control dams & retarding basins Levees and associated flood gates Bypass floodways Channel improvements Floodplain Risk Management Studies examine flood hazard, damages and flood risk management options for the full range of flood risk in the study area. They provide: information for the community, committee and councils to consider the relative merit of the different management options; detailed information on the benefits and costs of options from a practical, and social, environmental, physical, and economic feasibility perspective. an opportunity to carefully consider the ability to implement any proposed measures, as without this ability, an adopted management option achieves nothing. councils with an opportunity to strategically examine potential new development and redevelopment areas. This can involve both examination of the impacts of the development on flooding and the impacts of flooding on the new development area to determine how to develop new areas compatibly with the full range of flood risk. A properly scoped and undertaken floodplain risk management study provides an excellent tool for making robust flood risk management decisions. Determining the Most Appropriate Set of Management Options for the Situation The decision on the most appropriate suite of options to manage flood risk in a particular instance needs to consider the full range of flood risk for both existing and new development. Whilst the objectives in managing flood risk in new and existing development areas are almost identical, there are significant differences between management measures, as discussed below and summarised in Table 3. This highlights that management of flood risk to existing development relies upon: works or other management measures considering compatibility with other issues; emergency response management; and recovery planning. Whereas, management of flood risk to new development and redevelopment relies on: land use planning; Emergency response management; and recovery planning. Strategic Management 6

7 These differences highlight the need for: a suite of measures rather than a single solution to deal with flood risk management; and the need to consider emergency response planning as an integral part of managing the full range of flood risk to both existing and future development. Table 3 Strategic Considerations General Methods to Meet Objectives Danger to Personal Safety Existing Developed Areas Existing Works considering ERM Continuing Emergency Response Management (ERM) Property Damage Works Recovery Critical Infrastructure Works & Infrastructure Upgrades considering ERM Flood Dependant Works compatible, consider Ecosystems restoring or enhancing environment Societal Implications Works Recovery Other Environmental Works compatible Issues Other Natural Hazards Works compatible & Consider Joint Impacts Floodplain Risk Management Plan Adopt the Desired Set of Management Options New and Redevelopment Areas Future Flood Risk Land Use considering ERM Land Use Continuing Emergency Response Management (ERM) Recovery Land Use & Infrastructure considering ERM Land Use protect environment Land Use Recovery Management Decisions Compatible Management Decisions Compatible & consider Joint Impacts Floodplain risk management studies provide the necessary information and analysis to make effective and robust decisions on flood risk management. The consultant undertaking the investigation draft the plan in close consultation with the committee. It includes an implementation plan indicating priorities and a timetable for completing management measures. Priority should be given to measures that are relatively inexpensive, such as management of future development, which can control growth of flood risk and therefore have a significant impact relative to their implementation cost and associated effort. The council then considers the plan in the light of the management study, its statutory responsibility, and other constraints in deciding on a management plan to adopt. The adopted plan states the council s intentions for managing flood risk in the study area. Implementation Implementation of an Adopted Management Plan Undertaking studies and adopting a management plan does not manage flood risk. It is managed through the implementation of the recommendations of the adopted management plan. The committee remains in place to oversee and aid in the implementation of the plan. These may involve lobbying for plan implementation among councils many other priorities. Strategic Management 7

8 Benefits of Strategic Management Strategic flood risk management can result in a safer and more sustainable community by: improving compatibility of existing land use to flood risk; having future land use decisions made in light of the full range of flood risk and associated emergency management issues. Future development should therefore be compatible with flood risk; planning for risk by requiring appropriate development controls now rather than to try to engineer it out later using mitigation works at a significantly greater cost; providing more certainty in development applications; identifying critical infrastructure, assessing its vulnerability and the necessary improvements; providing better information for effective infrastructure management; allowing for appropriate consideration of societal issues; considering protection and perhaps enhancement of the environment; considering compatibility with the management of other natural hazard; and considering compatibility with environmental management measures. Implementation of Land Use Land use planning considering the full range of flood risk involves both strategic and development scale objectives and needs to consider both the impacts of development on flooding (and the associated affects on other property) and the impacts of flooding on the development for the full range of flooding. This involves both strategic level objectives and associated controls on development and development scale objectives, which look at how to best fulfil these controls for the individual site. These are discussed below. Strategic level objectives require effective management of flood risk to allow determination of: whether an area should be developed from a flood perspective. There are certain areas where development should not occur. These may be: floodways. Blocking these areas can raise flood levels or redirecting flows elsewhere affecting other properties or developments; and/or areas where flood hazard is too high; and/or areas with important flood dependent ecosystems. Emergency management is an important consideration in deciding whether an area is considered too hazardous from a flood perspective for development. the type of development that is appropriate for the location, when development is considered appropriate. The type of development that is suitable relates to the flood hazard. For instance, an aged care home is more vulnerable than an average residential development due to the inability of its residents to evacuate. Different types of development also have different impacts on flooding which need to be considered. the density of development that can be accommodated. This relates to the ability to effectively warn and evacuate potential development areas, and the impact the overall development (cumulative impact) may have on flooding and therefore on the flood risk of other properties. Strategic Management 8

9 appropriate management measures that can support development. This relates to measures, such as filling to reduce the likelihood of flooding or improvements to evacuation routes or centres to improve emergency management. It could also include additional protection to existing development to offset the impacts of the new development on it. appropriate management plans for critical infrastructure. New infrastructure should be available and accessibility during significant flood events or easy to reestablishment post event. This may require special design standards so that it is capable of performing its role in the expected conditions. This may mean wider evacuation routes with better drainage. Overall, these factors can be used to indicate to council the relative merits of different development strategies and allow them to consider the future development of the study area cognisant of the full range of flood risk. These considerations need to lead to the incorporation of decisions on appropriate development outcomes (excluding development from particular areas, or the type and density of development acceptable) or controls (minimum fill and floor levels) for the location into the councils planning instruments, and flood related development control plans and policies as outlined below. Controls can vary depending on what is necessary to provide appropriate protection so that development is flood risk compatible. Zoning in planning instruments, such as local environmental plans, can exclude development from areas where it is inappropriate, and restrict development types to those considered compatible with the level of flood risk. Therefore planning instruments are an appropriate locations for: delineating floodways (Reference 9) and excluding development from these areas. Compatible development is likely to be restricted to recreational (including playing fields), agricultural (in some cases) or environmental uses; delineating areas where the level of flood hazard, as identified in floodplain risk management studies, is too high to be acceptable for development. These are likely to be areas where danger to personal safety is unacceptably high; zoning to restrict development to uses identified as compatible with the level of flood risk on the land in management studies; and delineate important flood dependant ecosystems to protect these from development. More specific development conditions are applied within development control plans or flood policies. These ensure that developing specific land parcels consistent with their zoning, determined above, adequately addresses flood risk. They can place restrictions on development, which could include: requirements for minimum floor and fill levels; the allowable density of development within the area; consideration of design issues to address danger to personal safety, such as special design criteria for evacuation routes which may include external works such as road or bridge upgrades to facilitate safe evacuation from sites and associated developer contribution; requirements to allow for effective evacuation of the area, such as road layouts or special trafficable links from cul-de-sacs to facilitate evacuation to high ground; and special building requirements to reduce structural damage due to flooding, or flood damage. Strategic Management 9

10 Zoning and development controls aim to ensure development is flood risk compatible. Development scale objectives consider how to most appropriately apply controls derived at the strategic level (outlined above) to developments allowable under strategic level planning (compatible with the zoning). This involves considering: what conditions apply, including minimum floor levels, etc; how the site can be effectively developed with least risk given the constraints; what particular difficulties there may be in developing the property; and how these and any associated environmental issues can be addressed. Conclusions Strategic flood risk management is the control of the impacts of the full range of flood risk on people and property within a long term planning and policy framework to meet appropriate community expectations and environmental management practices. It is the responsibility of local government with technical and financial assistance from the State Government. Flood risk management needs to look at a broader context than simple danger to people and damage to buildings in events up to a standard design event, such as the 1% AEP event. It needs to consider the management of larger flood events and in particular integration with emergency response and recovery planning, interaction with the environment and other natural hazard issues, and the role critical infrastructure has to fulfil in both response and recovery. Strategic management of future flood risk relies on appropriate land use planning in consideration of emergency response management. Strategic flood risk management can have a range of benefits for councils which, and if implemented, will result in a safer and more sustainable community. References 1. McLuckie D.B., Opper S. Cooperative Management of. Safer Sustainable Communities 2003 Australian Disaster Conference, Canberra, September McLuckie D.B., Role of Land Use in Management. Papers & case study for Risk Based Land Use Course, Australian Emergency Management Institute, Mount Macedon, Dec. 2002, March 2003, Perth July McLuckie D.B., M.F. Porter - Cooperative Management of Floodplain Management Investigations. Paper delivered at the 42 nd Annual Floodplain Management Authorities Conference at Kempsey, 3 May McLuckie, D.B., Bodycott, J.R., Floodplain Management Manual Implications for Urban Areas. Paper to Stormwater Industry Association, Sydney, 22 nd Aug NSW Government, Floodplain Management Manual: The Management of Flood Liable Land (2001). 6. Bodycott, J.R., McLuckie, D.B. Flood and Other Water Damage Mitigation. Paper to at the 6 th Annual National Water Conference in Melbourne, July Smith D.I. Urban Floodplain Management: Where From, Where to? 39 th Annual NSW Floodplain Management Authorities Conference, Tamworth, May Keys C. Campbell P. Herbert M, Opper S. Councils and the State Emergency Service: Developing the Partnership in Flood and Floodplain Risk Management. 43 rd Annual NSW Floodplain Management Authorities Conference, Forbes February Howells L.A., McLuckie D.B., Collis G, Lawson N Floodways, Can One Size Fit All. 43 rd Annual Floodplain Management Authorities Conference Forbes, February Strategic Management 10