Modelling urban transition: A case of rainwater harvesting

Cities are increasingly exposed to extreme climate events such as floods and droughts. Land use change is also expected to reduce the availability of green spaces and intensify extreme heat events. Given these pressures on the quality of life of urban dwellers, there is a great need to improve the integrated management of water to enable sustainable development of rapidly growing cities and improve human well-being. A promising way to make urban communities more liveable is to invest in green water technologies, that is, decentralised and low-energy water supply, wastewater and stormwater solutions, to foster the transition to more sustainable and resilient cities. However, the adoption of multifunctional water technologies is a complex issue that requires cross-disciplinary approaches, demanding innovative thinking and practice. Despite the increasing body of literature on the benefits of decentralised water technologies, several barriers to their adoption remain. This paper uses an agent-based model that integrates social and environmental factors, as well as economic evaluation of water services provided by water technologies to assess the decision-making of two types of agents. The model is applied to evaluate incentive-based strategies to increase the adoption of rainwater tanks in Melbourne, a city that has suffered from severe droughts over the last decades. The model shows that using economic evaluation may not be adequate to understand the dynamics of rainwater tank uptake. Social factors such as public education might have played a role on decisions of households. This tool will be further tested and validated to explore policies and robust strategies to enable sustainable water management in rapidly developing cities.