10icud Paper Template

The application of Water Sensitive Urban Design (WSUD) in most regions around the world focuses on delivering the technology to new areas, or “greenfield" development. While it is a noble cause to pursue this, are we neglecting where we have failed to fix water resource management in the past, namely our existing urban areas? This paper shows the comparative effectiveness of greenfield versus retrofit WSUD strongly favours the latter, though methodologies to implement it at the scales necessary are not yet well understood. Recent modelling studies on populated centres in Australia have been conducted through linking WSUD performance prediction through the MUSIC modelling software with the “whole-of-catchment” context model E2. The use of these two models together shows that simply focusing the application of WSUD to future development will certainly lead to significant reductions of pollutants being exported from those areas, however the overall impact at the catchment scale is minimal and difficult to justify in isolation. This modelling shows that the retrofit of existing urban areas with WSUD technologies are where the greatest gains are to be achieved, and these, when combined with point source load reductions and rural diffuse management are the measures which have the potential to deliver restored waterway condition. The difficulty with simply predicting that the retrofitting of WSUD measures is what is needed ignores the challenges of implementation. Recent urban retrofit projects in several cities and regional centres have showed that the challenges, while sometimes significant, can be overcome. From the experience gained in these retrofit applications, the major issues facing wholesale retrofit of WSUD appears to be more political, financial and institutional, rather than being limited by technology. This paper argues that what is required is a process that embeds the implementation in existing on-the-ground activities such as drainage works, road maintenance and street scale landscaping, and also provides avenues to target urban renewal. This process should aim to standardise and simplify the various WSUD measures suitable for retrofit applications. Through this, the necessary “adoption” rate to provide the wholesale change is likely to be achieved. The use of modelling tools therefore shows how our current focus of facilitating the implementation of WSUD through new or greenfield development may fail to improve existing water quality issues. The paper demonstrates that existing problems and past failures are best addressed through retrofitting WSUD on the existing development areas.