Cities as Water Supply Catchments: Urban rainfall in a changing climate (Project B1.1)

Overview

Throughout its history, Australia has faced a highly variable natural climate with extreme weather events such as droughts, floods and bushfires. A changing climate will likely exacerbate this situation in terms of frequency and intensity of events and place more stress on communities, infrastructure, food production and ecosystems. Resilience to this changing climate will require better understanding of rainfall patterns and the development of enhanced tools for rainfall projections at the scale relevant to the design of stormwater systems.

This project aims to develop a comprehensive model to simulate probable rainfall in Adelaide, Brisbane, Melbourne and Sydney at a small enough scale (~ 2 kilometres) that would reliably support rigorous design of stormwater treatment and harvesting systems. This model will help urban planners and designers in government and industry better predict future rainfall in Australian cities to ensure that new or alternative urban stormwater management systems are environmentally and economically resilient to the uncertainties and extremes of a changing climate.

Key outcomes

Climate projections of rainfall (precipitation) are of limited value without quantitative assessments of the uncertainties involved. The central thrust of the research was to provide high-resolution projections of the future rainfall for Adelaide, Brisbane, Melbourne and Sydney, along with reliable estimates of the uncertainty in these projections. This also included a simulation of statistical properties of the current rainfall in those cities.

Researchers conducted a feasibility study for Perth, for which key datasets, in particular radar data from the Bureau of Meteorology, were previously not available. The development of the project will be applied to all cities and will ultimately lead to the provision of an ensemble of local rainfall scenarios.