Australia is currently experiencing extreme climate events regularly and at an increased frequency. Heat waves are increasingly common in Australia and present a significant challenge to major Australian cities already experiencing intense urban heat islands (UHIs) and increased minimum temperatures from global warming.This intersection of UHIs, global warming, severe droughts, and heat waves, whilst not unique to Australia, is driving innovation in Australian cities with regards to water resource capture, storage and use to adapt to heat and drought events.
This presentation synthesises how and why Autralian water and land management industries and local governments are investing, experimenting and now rolling out new ways of using water to provide cool refuge for residents, for urban biodiversity and drought relief to vulnerable but valued vegetation systems. Can these approaches be adpoted and adapted to other international cities and countries that will experience the harsh and variable climates that Australian cities now face?
Results/Conclusions
For irrigation to support vegetation threatened by drought, we find many reports of mature urban trees that have access to ample soil moisture, and which are not necessarily as water stressed as commonly assumed. This may be counter-intuitive, but it has long been observed that cities have high water tables due to leaking transport systems that recharge aquifers with imported water. land managers should confirm the occurrence of water stress, as there are many other factors that can contribute to dieback and mortality in urban vegetation.
For irrigation or misting to alleviate heat stress in urban fauna, we find very few studies that have tested the efficacy of evaporative cooling for the benefit of fauna in urban greenspace. However, there is ample evidence that relatively small increases in air temperature during extreme stress can negatively impact faunal physiology, behavior, and mortality. Therefore, there is potential for beneficial effects of irrigation on urban fauna, which are generally concentrated in relatively small refuges or greenspaces. Because irrigation measures do not necessarily have to be implemented on large spatial scales to target key faunal populations, these measures could be both feasible and effective to help faunal species adapt to rising temperatures.
In the case of human thermal comfort, adaptation measures involving evaporative cooling must be implemented on a relatively large spatial scale to effectively and fairly benefit large urban populations. To avoid further stressing urban water resources, these measures would need to rely on alternative, recycled, and/or non-potable sources of water.