According to IPCC [8], countries including Australia have been experiencing more frequent and heavy rainfall events since the 1950s. The Bureau of Meteorology (BoM) [17] confirms that information by stating that rainfall intensities have indeed increased in Australia, especially short-term extreme rain events, particularly in South Australia. Although heavy rains are expected to become stronger, the region is experiencing drier weather conditions, higher evapotranspiration and increases in rainfall intensity, a pattern that is likely to continue in the future [11,18].

South Australia is already witnessing more intense summer storms (flood events) and winter rainfall declines [19,20]. On top of that, bushfire risks have risen in the region and longer fire seasons are expected due to dryness, annual temperature increases and extremely hot days (>40 °C) [18]. This scenario is causing severe economic losses, mostly for the agricultural industries, and harming the well-being of the population [15]. Therefore, climate change has become an important consideration for the country’s economies and sustainable development, especially considering long-term water resources management.

Overall, climate change is expected to have an adverse effect on rainfall intensities for many locations in Australia. The Australian Rainfall and Runoff (ARR) is a part of the National Climate Change Adaptation Framework, which is being recognized as an important planning initiative to promote the safety and well-functioning of new and existing infrastructure [21]. Future climate tendencies are intrinsically dependent on human behaviours and, therefore, subject to a lot of uncertainties [22].

The RCP scenarios are used in global climate models (GCMs) and can range from the lowest carbon emission scenario (RCP 2.6) to the highest concentration pathway (RCP 8.5) [23]. It is worth mentioning that although RCP 8.5 is considered an ‘extreme’ scenario, research is labelling it as the most ‘normal’ or realistic future scenario [22].

In the Australian context, three WSUD infiltration systems are frequently used: leaky wells, infiltration trenches and soak-aways [3]. Those systems can alleviate the quantity of water being directed to the conventional drainage systems by collecting stormwater runoff, storing it and slowly releasing it into the soil, not only assisting in flood management and soil irrigation but also in the removal of pollutants from the water [10,24]. Ahammed et al. [24] investigated the techno-economic analysis of WSUD technologies with conventional drainage systems for a medium catchment of South Australia and observed that the systems are techno-economically feasible. Despite its benefits, there are some constraints to infiltration systems: the structure must be placed in soils with high permeability and with a relatively low water table [3,25].

Furthermore, infiltration might also require the implementation of a pre-treatment, such as a gross pollutant trap (GPT), to remove larger solids of the stormwater runoff before it enters the infiltration system. Those systems are also known as ‘sediment traps’ or ‘litter traps’, and they will reduce the risks of clogging the infiltration device [12].

The soak-away is an infiltration ‘tank’ system placed underground, which can offer great advantages by not sacrificing areas that could be destined for other purposes. These infiltration systems can be placed in highly populated areas, reducing local runoff volume and mitigating flood events [5]. The structure of the soak-away can be enveloped within a permeable geotextile to allow the gradual release of water collected from the roof and other sources to the surrounding soil [26]. To attend to a larger catchment area, the soak-away structures can be combined to increase their capability to store a bigger volume of stormwater runoff [26].

The soak-away size will depend on some factors such as the soil type of the region as well as the amount of predicted stormwater volume to be received and stored by the system [27]. As mentioned before, an important cause of failure of the soak-away is clogging, which happens when solids accumulate in between void spaces of the structure, leading it to easily overflow [28]. Another concern is the stability of nearby foundations as soak-aways tend to increase the water content in the soil, which might be dangerous in expansive soils [25]. As an example of soak-away implementation, the City of Burnside Council has recently started a project regarding the installation of infiltration systems for capturing stormwater and delivering it to young tree surroundings. Those systems were called ‘B-pods’, which also contributed to reducing the velocity and amount of stormwater volumes flowing to urban watercourses [29]. With the impermeabilization of the surface, projects like ‘B-pods’ can make a great difference, especially during drought periods or extreme weather events due to climate change impacts.

Currently, very little academic research focuses on the design resilience of infiltration-based WSUD technologies to climate change, such as Zhang et al. [30] who investigated a constructed wetland and a biofilter system and Tirpak et al. [31] who evaluated bioretention cells. There is limited information regarding the performance of soak-away in the long term, considering climate change impacts on rainfall patterns.