Authors: L. Liyanage, P. Vince.

This paper was presented at Corrosion & Prevention 2023.


Global temperature rises have a significant impact on water and wastewater treatment processes, and the infrastructure required for these processes. In particular, higher stream temperatures, varied water chemistry, higher organic content, seasonal variations, and intense rain events are anticipated. This paper discusses mitigation measures that can be taken to accommodate these changes. Specific discussion of the role of durability professionals is included. The efficacy of existing corrosion protection measures for sewers will be briefly reviewed, and consideration of future requirements discussed. A specific case study evaluating the anticipated climate changes and system responses for the water and wastewater systems at York, Ontario, Canada will be discussed. It was found that extreme temperatures pose the highest risk to effective operation of water infrastructure and extreme rain events pose the highest risk to the effective operation of wastewater infrastructure.

Keywords: climate change, water infrastructure, materials degradation


The Durability Specialist performs a crucial role in responding to infrastructure impacts caused by climate change. Materials degradation knowledge is an invaluable input to assessing infrastructure performance and remaining life. The Durability Specialist is able to collaborate with other engineering disciplines such as asset managers, process engineers and structural engineers to develop designs and maintenance plans that incorporate suitable measures to mitigate the impacts of climate change on infrastructure.

The global climate system is complex consisting of oceans, water bodies, land, ice, air, plants, and animals. The key energy source that drives the system is the sun. The global climate is measured by a number of parameters including temperature, humidity, atmospheric pressure, wind, precipitation, atmospheric particle count and other meteorological systems. Consideration of all of these factors provides an account of the overall state of the climate system.

The Intergovernmental Panel on Climate Change (IPCC) defined climate change as: ‘Change in the state of the climate that can be identified (eg by using statistical tests) by changes in the mean and/or the variability of its properties, and that persists for an extended period, typically decades or longer.’

The 2022 CSIRO and Bureau of Meteorology State of the Climate Report noted that Australia’s mean surface air temperature has increased by 1.47°C since 1910 and the average sea surface temperature has warmed by 1.05°C since 1900 (see Figure 1). Figure 1 Surface air temperature and sea surface temperature in Australia

IPCC climate modelling predicts significant increases in temperature over the coming decades (IPCC, 2023, 3.2°C by 2100 based on continuation of policies implemented by the end of 2020). Temperature rise has a significant impact on the operation of the Earth’s climate system. A small rise in temperature is predicted to cause melting ice, floods, droughts, food production challenges, and variable weather systems.

Considerable efforts are being expended to mitigate the effects of climate change. These primarily focus on reducing or preventing the emission of greenhouse gases. For example, using renewable energy, using relevant new technology, making existing equipment more efficient, changing consumer behaviour. However, these are not the focus of this paper.

This paper focuses on climate change adaptation. That is, anticipating the adverse effects of climate change and taking appropriate actions to prevent or minimise damage caused by climate change. At the same time, also taking advantage of any beneficial effects arising from climate change. In particular, the focus is on water and wastewater operations, noting that over 80% of an asset life is the operations stage. This paper introduces a tool to assist asset owners – the Climate Change Adaptation Plan.


It is anticipated that climate change will contribute to an increased number of climate related events, some of which will impact water and wastewater infrastructure. The following are considered foremost on that list: intense summer heat, river flow variation, high river temperature, intense rain, low snow cover, higher weed growth, longer growing seasons, prolonged droughts, variable seasons, higher organic content in water, water chemistry, cyclones, sea level rise, and forest fires.

These events will impact the primary infrastructure such as treatment plants, pump stations, distribution pipelines, collection pipelines, and networks. It will also affect the support infrastructure such as buildings, warehouses, and maintenance facilities as well as administrative functions. Energy supply, telecommunication (including control signals), transportation and access will also be affected.


Many models predict changes to river flows, particularly a decline in mean annual flow (Martz et al (2007), AMEC (2009), St Jacques et al (2013)). But this is not only a change in total volume but also a change in what seasons the flow will occur. In these models, spring flows are predicted to be higher, summer flows lower and autumn flows much lower. This is concerning because the summer is the high demand period for water, and this corresponds to lower flows due to a longer growing season and hotter summers. See Figure 2 below for an example in Canada(summer months June – August).

Groundwater will also be impacted, mainly due to the higher temperature and lower recharge rate which will impact the groundwater quality. Demand for groundwater will likely increase due to the need to supplement river water during low flow months. This is expected to be experienced globally, especially since 70% of water globally is currently used for agriculture (mainly irrigation) (Boretti and Rosa, 2019) and is heavily reliant on river flows. Boretti and Rosa (2019) highlight that current global groundwater withdrawals are near maximum sustainable levels.

Prolonged droughts, flooding, forest fires, extreme weather events, prolonged algae growing season, and erosion will all negatively impact water quality.


Table 2 provides a tabulated representation for some of the anticipated responses to the impact of climate change. Each aspect of climate change will have a different impact for different infrastructure. Warmer water will lead to more algal growth for water storage assets but will lead to more corrosion for sewer assets. For each impact, adaptation and control measures are listed.


The mechanism for deterioration of concrete assets exposed to raw sewage have been known for some time. Thistlethwayte et al (1972) identified the interaction of hydrogen sulphide (produced by bacteria) and moisture creates an acidic liquid which attacks the reactive components of concrete. Higher temperatures associated with climate change are anticipated to exacerbate the hydrogen sulphide production and air space humidity leading to increased deterioration rates.

Many techniques have been utilised to reduce this impact such as protective coatings, cementitious coatings, and chemical dosing. Vince (2009) identified the success of particular coatings which has been verified by testing in the SA Water biogenic chamber (Vince, 2018). The success of geopolymers and calcium aluminate cement has also been documented (WSAA, 2021). The use of liquid magnesium hydroxide has also been found to have some success (Sydney Water, 2014).

However, Wells and Melchers (2017) found that if humidity in the air space in sewer systems can be reduced, the rate of deterioration can be significantly reduced. Introduction of ventilation systems is a key design measure that can enable extended durability of sewer systems and counter the impacts of climate change.


A Climate Change Adaptation Plan was developed for the operation of the water and wastewater systems for the Regional Municipality of York, Canada. York is situated near Toronto in Southern Ontario. It has a population of 1.1million people. The development process is illustrated in Figure 3.

Figure 3 Climate Change Adaptation Plan Development process

The first step is to gather and analyse relevant historical climate data for the site. Climate data is available from a number of sources including online databases. In Australia, the Bureau of Meteorology publishes a ‘State of the Climate’ report on a biannual basis. They are able to supply climate data such as temperature, rainfall, and evaporation for specific sites and have an extensive history for most of Australia. The Government of Canada provides a similar service via the Canadian Centre for Climate Services.

The second step is to identify future climate events. As discussed above, there are a wide range of impacts of climate change but these need to be narrowed down to what impact do those changes have on water and wastewater operations. In general, it will be hotter and drier but there will be more extreme events. When it does rain it is likely to be more intense for short periods. Coastal impacts will increase due to sea rise and coastal storms. Many • Analyse historical climate data• Identify future climate events• Identify adaptation approaches• Develop planning considerations• Assess risks and prioritise adaptation approaches• Recommend design and operational guideline changes• Develop Climate Change Adaptation Plan 7wastewater plants around Australia and located near the coast and rivers to take advantage of gravity systems. Current 1 in 100 year events are expected to become more frequent.

The third step is to identify adaptation approaches. Examples are listed in Table 2 above. Considerable experience and system understanding is required to develop appropriate solutions. By 2050, Eastern Australia is projected to be in drought 36-57% of the time. Higher temperatures are anticipated to cause higher deterioration rates in gravity sewers. Population growth would be expected to increase the volume of flow in sewers, but decreased rainfall will decrease the flow. A combination of physical and chemical methods will be required to protect the head space surfaces of sewers.

The fourth step is to develop planning considerations. Once adaptation approaches are formulated there needs to be a detailed examination of how they can be introduced. This will require consideration of budgets, timing, impact on operator skill set, environmental impact, design life and initial comparison of options. Note that the supply chains and resources required to implement change will be also impacted by climate change. Knowledge of asset condition will be critical to planning capital interventions. Condition assessment intervals may need to be reduced so that the impact of climate change can be accurately tracked.

Clearly there are going to be some approaches that are incongruous with each other. In step five it is important to assess the risks associated with each approach and prioritise the approach with the best outcome. Multi criteria analysis and similar considered techniques are required to evaluate the viable alternatives. Table 3 highlights some aspects of this prioritisation process. The cells highlighted in red are considered the high priority, the orange are the moderate priorities and the yellow are the low priority. This highlights that for some infrastructure the trend towards high temperature will have the most impact and therefore it is more important to develop adaptation strategies for that infrastructure to adjust to elevated temperatures. The final two steps involve providing recommendations for design change and for operational change and putting all the outputs together to finalise the Climate Change Adaptation Plan.

The outcome of the process for York was the identification of key vulnerabilities of the municipality water assets to climate events. A summary is presented in Table 3.

Table 3 Key Vulnerabilities and Prioritisation

Table 3 provided the basis for developing the Climate Change Adaptation Plan – effectively a resilience road map for water and wastewater assets in the region. A response to every climate event scenario was developed and progressed by the York Regional Municipality. This process involved interaction at many levels. The climate data collection and analysis was conducted by climate specialists. The impact on treatment processes was determined by process engineers. The impact on the service life and performance of assets was determined by the durability specialists. The development of adaptation options was a joint effort between climate specialists, process engineers, and operators.

The implementation of process changes has involved considerable training of operators. The reasons for change and associated improvements need to be carefully communicated to engender commitment and realise wider benefits.


Climate change will have significant effects on all water and wastewater infrastructure. A valuable tool in managing those effects on water and wastewater operations is the Climate Change Adaptation Plan. This is developed by analysing historical climate data, identifying future climate events, developing adaptation strategies, and implementing them. The successful implementation of such plans relies on close collaboration between many water professionals. In particular, the durability specialist plays a vital role in responding to the impact of climate change on water and wastewater infrastructure.


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The authors would like to acknowledge the support of colleagues at WSP in preparing this paper.


Lalith Liyanage, National Technical Director, Wastewater at WSP in Canada.

Dr. Lalith Liyanage is a process engineer specializing in municipal and industrial water and wastewater treatment with extensive knowledge of chemical, physical, and biological treatment of various industrial wastewater including, oil-sands processing wastes, mining, power and pulp and paper waste. He is an expert in Biowin modelling of wastewater treatment processes and developing customized treatment models for pond systems. In his current role as a Regional Process Leader at WSP, in addition to the local business development, he supports corporate projects nationally and internationally. In addition to being a practicing process engineer for more than 30 years, Lalith has published numerous papers related to water and wastewater treatment. He has received the prestigious Rosen M. Harvey Award for one of his publications in the area of water disinfection. He regularly conducts operator training workshops for biological treatment, fermentation, advanced membrane treatment, biosolids management and climate resilient water wastewater infrastructure development.

Paul Vince, Principal Materials Engineer, WSP Australia.

Paul Vince is a Materials Engineer with considerable experience in the water industry particularly focussed on condition assessment and durability. Paul has worked as an asset owner of pipelines, concrete structures, treatment plants, and water storages. Paul has proven success in obtaining detailed understanding of asset condition and determining optimal treatment options for life extension or replacement. He offers a good understanding of corrosion principles and the mechanisms for concrete and metallic structure deterioration. He has detailed knowledge of repair methods and products and rehabilitation techniques, which complements his expertise in materials selection, welding, coatings, and stainless steel.



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