Submission to Senate Inquiry Inquiry Into Current and Future Impacts of Climate Change on Housing, Buildings and Infrastructure

A group of concerned Engineers and Scientists Submission to Senate Inquiry Inquiry into current and future impacts of climate change on housing, buildings and infrastructure

August 2017

About Us

We are a group of concerned engineers and scientists. The professional interests of our group include the planning, design and operation of potable and irrigation water supply, wastewater and stormwater systems and in the planning, design and operation of other infrastructure that may be exposed to risks from inundation by stormwater and flooding. Our planning and design work considers how we can make infrastructure operate in a robust and resilient manner across the spectrum of hydro-climatic conditions that are likely to be encountered, which often leads us to a particular focus on the extreme wet and dry ends of this range.

The views that we have provided in this submission are our own and do not necessarily represent the views of our employers or other organisations that we may be affiliated with.

Name and qualifications Position(s) and Organisation(s)

Phillip Jordan, B.Eng.(Civil), Ph.D., Principal Hydrologist, Hydrology and Risk Consulting, and C.P.Eng., M.I.E.Aust., R.P.E.Q. Fellow of the Peter Cullen Water & Environment Trust

Michael Wrathall, B.Eng.(Civil), Manager Knowledge Coordination, NSW DPI Water, and Fellow C.P.Eng., M.I.E.Aust. of the Peter Cullen Water & Environment Trust

Richard Cresswell, B.Sc.(Hons), Principal Hydrogeologist & Water Discipline Lead, Eco Logical M.Sc., Ph.D., M.Aus.I.M.M., J.P. Australia, Fellow of the Peter Cullen Water & Environment Trust (Qual)

Katherine Daniell Senior Lecturer, Fenner School of Environment and Society, The B.Eng.(Civil)(Hons), B.A., Ph.D., Australian National University and Fellow of the Peter Cullen M.I.E.Aust. Water & Environment Trust

Penelope .J. Springham, B.App.Sc. Fellow of the Peter Cullen Water & Environment Trust (Env Health)

William Glamore, B.Sc., Ph.D. Associate Professor and Principal Research Fellow Water Research Laboratory, School of Civil and Engineering, University of New South Wales, Fellow of the Peter Cullen Water & Environment Trust and Winston Churchill Fellow

Andrew Herron, B.Env.Eng.(Hons) Senior Hydrologist, Ecological Australia

Contact Committee inquiry members are encouraged to contact our group’s representative, Dr Phillip Jordan, via email

Front cover image Obtained under licence from www.shutterstock.com

Synopsis

Historically, water-focused infrastructure (such as reservoirs; flood-relief installations; bridges; urban buildings and drains) has been designed based on records (data) of previously experienced rainfall extremes and averages. However, in recent decades, rainfall has been considerably more variable in its amounts and characteristics.

In relation to water resources, floods, and water quality management in urban streams, this submission points out that: (i) infrastructure-design guidelines need to be reviewed and updated more often to take account of the variability now being seen in rainfall across Australia; and (ii) more widespread data collection, as well as climate change projections, are essential to improve predictions of the impacts of rainfall or lack of it.

The submission makes 15 recommendations in response to the terms of reference of this inquiry:

 Three recommendations in relation to water resources.  Two recommendations in relation to groundwater.  Eight recommendations in relation to flooding.  Two recommendations in relation to urban stream water quality.

There are also two recommendations in relation to Australia’s role in mitigating greenhouse gas emissions.

Context of our submission

Historical data has conventionally been analysed and used to assess the robustness of infrastructure design to hydro-climatic variability. In practice, most design has assumed that data collected in the instrumental record (over approximately the last 150 years) will represent the variability over the foreseeable future.

Given our current understanding of climatic variability and climate change, it would be unwise to continue with undertaking hydrological analysis and design using only historical data. Milly et al. (2008) summed it up in the title of their seminal paper, ‘Stationarity is dead: Whither water management?’. The decline in historical inflows to Perth’s dams, as shown in Figure 1, is one of the clearest Australian examples of this.

Figure 1 Historical inflows to Perth’s water supply dams (Water Corporation, 2017)

Water resources considerations

Policy Guidelines for Water Planning and Management have been developed for water planners and managers in the state and territory jurisdictions (Australian Government, 2010). A guideline module for Considering Climate Change and Extreme Events in Water Planning and Management has been developed as a supporting document (Australian Government, 2017).

Groundwater considerations

Groundwater underlies all of Australia and the water that exerts a hydrostatic pressure in the pores of the aquifers constitutes both a water source and a structural element beneath any urban development. Design criteria for any infrastructure therefore has to address the potential impacts on and from this resource. While most States acknowledge the critical nature of our groundwater resources, development is predicated on current conditions and a combination of impacts from de-watering for construction and on-going impacts on down-stream users, including the environment (e.g. The Aquifer Interference Policy (2012) in NSW). While this may include consideration of future climate change on the receptors of these potential impacts, less consideration is placed on the effects of natural changes to the groundwater systems due to future climatic changes to recharge and discharge. Thus, for example, reduced recharge in Western Australia due to the decreased rainfall regimes results in lowering of groundwater tables such that drying of the unsaturated zone above aquifers requires greater recharge in the future to facilitate a unit response to groundwater levels and supplies. The reduction in recharge and lowering of water pressures and levels also results in compaction of aquifer sediments and consequent settling and subsidence of the land surface. This may be compounded by increased groundwater extraction during lower rainfall (and hence recharge) regimes as dams are not replenished.

Flood considerations Guidelines need to be more frequently reviewed and updated

Guidelines for the design and planning of infrastructure, buildings and housing that could be affected by flooding are provided in Australian Rainfall and Runoff (referred to in the remainder of this submission as ARR). The Institution of Engineers Australia (now Engineers Australia) first released ARR in 1958 with the aim of providing Australian designers and analysts with the best available information on flood estimation. Engineers Australia has updated the ARR three times since 1958 and the latest edition was released in draft form in 2016 (Ball et al., 2016), with a final release expected in the next few months.

We note that there was a 30-year gap between the release of the third edition of ARR, in 1987 and today. The most recent release of ARR is the result of considerable effort by Engineers Australia, Geoscience Australia, the Bureau of Meteorology and others in the hydrology and engineering professions between 2012 and 2016.

The long gap between updates of ARR had detrimental impacts on design and planning of infrastructure. Since about the early 2000s, it had become obvious to well-informed hydrologists and engineers that the 1987 edition of ARR was becoming increasingly out of date. Consequently, when ARR was recently updated, there were large changes in the Annual Exceedance Probability (AEP; probability of a flood event occurring in any year) associated with the design floods for particular catchments and locations. These changes were due to large changes in the accepted industry-standard techniques for design flood estimation over these three decades, and the accumulation of a much larger available record of observed rainfall and streamflow data.

Infrastructure that was designed in accordance with the 1987 edition of ARR to have immunity against flooding in, for example, a flood event with an AEP of 1%, may then be found, in accordance with the revised ARR, to have considerably smaller or considerably larger flood immunity. The changes between the editions of ARR are sufficiently large that, in some cases, the AEP of the design event for a particular piece of infrastructure could change by as much as, or more than a factor of 10.

Need for more widespread data-collection and climate-change projections

The design rainfall estimates provided with the 1987 edition of ARR were based upon some of the rainfall station data collected up until the mid-1980s. The design rainfall estimates updated by the Bureau of Meteorology in 2016 for use with ARR were based upon a more extensive database of rainfall, drawing upon more than 30 years of additional rainfall data and data from extra rainfall stations. The rainfall analysis for the 2016 edition also drew upon more contemporary techniques for statistical and spatial analysis (Bureau of Meteorology, 2016).

Assessment of flood risk for very rare events is of particular importance to the safe design, maintenance and operation of dams. Design flood estimates for rare events are particularly influenced by estimates of Probable Maximum Precipitation, and these estimates were last updated by the Bureau of Meteorology in 1996 and 2003 (Bureau of Meteorology, 1996, 2003a, 2003b). The AEP of the Probable Maximum Precipitation influences flood estimates for the planning and design of all infrastructure that is affected by floods with an AEP rarer than 1 in 2000, and recommendations on this AEP value are currently based on a 1999 publication (Laurenson and Kuczera, 1999, referenced in Nathan and Weinmann, 2016). The potential influences of climate change on Probable Maximum Precipitation estimates were last reviewed by the Bureau of Meteorology in 2009 (Bureau of Meteorology, 2009).

The 1987 edition of ARR did not address potential impacts of climate change at all, so approaches to incorporating climate change prior to the release of the 2016 edition of ARR varied considerably between studies, where climate change was considered at all. Chapter 6 of Book 1 of the revised ARR addresses climate change considerations (Bates et al., 2016).

One of the tools provided with ARR is the ‘regional flood frequency estimation tool’. This is a web- based tool that provides design peak flow estimates for any non-urban catchment that has not had its hydrological response significantly altered by construction of a dam or weir, drainage or irrigation infrastructure, soil conservation works or mining activities or where large scale land clearing has taken place during the period of record.

Two significant limitations of the regional flood frequency estimation tool are pertinent to this submission.

(i) It is only applicable to catchments that are less than 10% urbanised (by area) (Nathan and Ball, 2016). (ii) It has been created using an analysis of historical gauged streamflow data and therefore does not incorporate projections for climate change.

The challenges with deriving design flood estimates for urbanised or partly-urbanised catchments are striking. The problem is the lack of streamflow gauge records of sufficient length and quality in urban areas. Nathan and Ball (2016) remark that:

“Perhaps the most obvious limitation of Flood Frequency Analysis is that it relies upon the availability of recorded flood data. This is a particular limitation in urban drainage design as there are so few gauged records of any utility in developed catchments.”

The regional flood frequency estimation method for rural catchments was derived from long-term records from 853 gauged Australian rural catchments but the number of Australian urban catchments with long-term records would be less than 20.

Retallick and Testoni (2016) further expound the problems with developing flood estimates for Australian urban catchments:

“As part of the ARR revision projects a search was undertaken to uncover long term streamflow gauges in urban areas. Insufficient data was uncovered to allow the development of an urban flood method. The existing urban streamflow gauges should be given special recognition for their importance to the development of future techniques. This recognition could be used to help justify the ongoing support and maintenance of these gauges. It is highly desirable to identify a set of high quality urban catchments to allow new methods to be tested against observed data. Such catchments should have long term gauged records, good quality rating curves, and a reasonably stationary level of development.”

Water quality considerations Need for climate-change projections to update guidelines

Over the last few decades, state, territory and local governments have progressively introduced legislation and regulations that require the incorporation of water sensitive urban design principles in the design and upgrade of urban infrastructure, housing and buildings. Water sensitive urban design is the integrated design of the urban water cycle, incorporating water supply, wastewater, stormwater and groundwater management, urban design and environmental protection (Joint Steering Committee for Water Sensitive Cities, 2009). Regulations typically require developers of new infrastructure to demonstrate the proposed development will achieve nominated target reduction in contaminant loads from those that would have occurred under pre-development conditions (e.g. Victorian Environmental Protection Agency, 2017).

To our knowledge, none of the water sensitive urban design regulations require developers to demonstrate that the proposed development will continue to provide the required target reductions in contaminant loads under projected climate change.

It is standard practice for proponents of development to produce a numerical model of the proposed development, demonstrating compliance with the policy objectives of the regulator in the applicable jurisdiction. The most common tool used to achieve this has been the Model for Urban Stormwater Improvement Conceptualisation (MUSIC) (eWater, 2016). To streamline the development application process, guidelines are in place for construction of MUSIC models in various local areas (e.g. for South East Queensland by Water By Design, 2010; for Greater Melbourne by Melbourne Water, 2016; for New South Wales by BMT WBM, 2015). The MUSIC modelling guidelines typically provide a standard climatic data set, which has been derived from analysis of historical rainfall and evapotranspiration data. The standard climatic data sets normally extend for a 10-year period that has been chosen to be representative of the full period of climatic data.

If legislation and regulations were to be modified to require developers to demonstrate continued achievement of contaminant loads under projected climate change, the MUSIC model guidelines and/or alternative modelling techniques would need to be changed to facilitate the development application process.

Response to the inquiry terms of reference

The adequacy of current state and Commonwealth policies to assess, plan and implement adaptation plans and improved resilience of infrastructure Water resources considerations

We recommend that state and territory governments should incorporate potential impacts from climate change and extreme events into water resources planning and management in a manner that is consistent with the relevant guidelines (Australian Government, 2017).

We recommend that management plans balance the need for clear guidance with the ability to adaptively respond to an emerging extreme event in accordance with agreed principles. In recognition that the droughts of the past may not necessarily occur in the same way as the droughts of the future, management plans ought not to be overly prescriptive.

We recommend that management responses to drought give due consideration to the local context, needs and priorities. The emergence of drought within a river system can be affected by a wide variety of factors, including the volume and timing of local rainfall, land use and land management practices, patterns of water demand and water use within the system, the relative priorities of certain water needs with high social or economic value, and river operational practices during dry periods. These local and regional factors can significantly influence the nature of the impacts of drought, how management responses ought to be designed, and how societal values are reflected in the relative priority of access during periods of water shortage.

Groundwater considerations

We recommend that state, territory, local and federal government legislation and regulations are modified to require developers of new infrastructure to demonstrate that groundwater resources beneath and adjacent to major works are assessed with regard to potential future climatic impacts on the resource and the compounded effects of potential increased local consumption and nature reduction in local recharge to the resource on the stability and longevity of the infrastructure in addition to impacts on the aquifers.

We recommend that future predictive models for groundwater impact assessments are required to incorporate projected consequences of future climate change predictions and not rely on synthetic climate series developed on past records.

Flood considerations

We have noted that the regional flood frequency estimation tool supplied with ARR uses historical data and does not allow for projected climate change. We recommend that appropriate funding be provided through Geoscience Australia to support upgrading the regional flood frequency estimation tool to allow users to produce regional flood estimates that incorporate climate change projections.

We recommend that Probable Maximum Precipitation estimates be reviewed and updated by Geoscience Australia and the Bureau of Meteorology on an approximately 10-year cycle. We recommend that the scope of this review should include a review and updated guidance on the AEP of the Probable Maximum Precipitation.

Advances are being made continually in the research and practice of flood hydrology and hydraulics. We recommend that these advances be introduced into ARR at relatively frequent intervals. We therefore recommend that adequate resources be provided to Geoscience Australia to undertake regular, approximately annual, reviews of and updates to ARR.

Even with regular updates of ARR, there will be the need for more substantial rewrites and updates. We recommend that appropriate resources be provided to Geoscience Australia and the Bureau of Meteorology, on approximately a 10-year cycle, to undertake major reviews and updates to ARR. This would include re-analysis of the full rainfall and streamflow data record, to synthesise the knowledge on climate variability and climate change that is revealed in the hydrological record.

The urban streamflow gauging network should cover catchments in all major urban cities and towns across Australia. We recommend that a strategy be implemented to install streamflow gauges and systematically collect and archive streamflow and stormwater pipe-flow data in a large number of urbanised and partly urbanised catchments. We recommend that the urban streamflow gauging strategy is funded for at least 10 years, capturing data in at least 50 catchments. This would provide a minimum viable data set that would support analysis of flood risk in urban areas over the coming decades, allowing for appropriate consideration of climate change on flood risk for urban infrastructure, buildings and housing.

Water quality considerations

We recommend that state, territory and local government legislation and regulations be modified to require developers of new infrastructure to demonstrate that water quality objectives will be achieved under current climatic conditions and under a reasonable projection of the future climate that could apply at the end of the design life of the infrastructure.

We recommend that standard climatic data-sets be developed for use with MUSIC models that would have national coverage. The standard climatic data-sets would include representative rainfall and evaporation data-sets applicable both for existing climate and for projections of future climate that could be applicable throughout the design life of proposed developments.

Mitigation of greenhouse gas emissions

The focus of this Senate Inquiry, and therefore our submission, has been on adaptation of infrastructure to current and future impacts of climate change. However, we want to make a final point on policies for mitigation of greenhouse gas emissions, as it pertains to planning and design of infrastructure.

Tourism and outdoor recreation are important industries in many parts of Australia and hence infrastructure and assets have been constructed and will be planned and constructed into the future to support these industries. Residential and commercial development has been and will in the future be attracted to the more spectacular parts of our nation. Some prominent examples include Queensland’s cities and towns near the Great Barrier Reef, beaches spread around the nation, and mountain resorts. The economic value of the Great Barrier Reef was recently put at $56 billion (Deloitte Access Economics, 2017) and the economic impact of the Australian alpine resorts was estimated at $ 1.8 billion per year in 2011 (National Institute of Economic and Industry Research, 2012).

Climate change threatens the ecosystems and hence the continued natural beauty of these areas. Climate change induced sea level rise, combined with tides and storm surge, also presents a direct threat to infrastructure and buildings in low lying areas. Whilst adaptation may be possible in the planning and design of the infrastructure and buildings themselves, including designing and constructing more risk-aware forms of relocatable/disposable infrastructure (Gordon, 2013; Daniell, 2013), there is a risk of both public and private sector investment in assets that may ultimately become stranded, as the primary reason for their existence is damaged or destroyed. Adaptation is only part of the solution.

We therefore recommend that the Commonwealth Government continues to take an active role in the Intergovernmental Panel on Climate Change to mitigate greenhouse gas emissions on a global level. We also recommend that the Commonwealth Government continues to implement policies that are consistent with Australia’s commitments to the Paris Agreement (United Nations, 2015).

Conclusion

Thank you for the opportunity to contribute to the Senate Environment and Communications References Committee into the current and future impacts of climate change on housing, buildings

and infrastructure. For more information, please contact our group’s representative, Dr Phillip Jordan, via email

References

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Australian Government (2017) Considering Climate Change and Extreme Events in Water Planning and Management: a module to support water planners and managers consider and incorporate possible impacts from climate change and extreme events on water resources. Accessible at http://www.agriculture.gov.au/water/policy/nwi/climate-change

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