Managing urban water system trade-offs using smart storages

Water balances in urban environments are changing as a result of population growth, urbanisation and climate and land use change. This has a number of potential impacts, including increased demand for water, increased flooding and a reduction in water quality, especially in receiving waters. The optimal placement and control of smart storages throughout urban catchments provide an opportunity to better manage these impacts, as this can reduce flood peaks, provide a source of water and improve downstream water quality. In this paper, the trade-offs between flood reduction, water supply benefits, water quality benefits, required total storage volume and costs are investigated for distributed storages with outlet control strategies that utilise different emerging control technologies and data analytics to varying degrees. These include (i) no outlet control (i.e. passive detention storages), (ii) smart outlet control to retain water between storm events and release all of the stored water from the storages prior to storm events, and (iii) smart outlet control to retain water between storm events and optimise releases from the storages throughout storm events based on forecasts of rainfall temporal patterns so as to minimise peak system outflows. This was done for an urban catchment in Unley, South Australia. Results indicate that the addition of both types of control (i.e. options (i) and (ii)) results in significant water supply and quality benefits, with option (iii) resulting in significantly increased flood benefits compared with options (i) and (ii). However, these benefits come at a cost, with options (ii) and (iii) resulting in a 62% and 76% increase in cost, respectively, compared with option (i).