HowLeaky (McClymont et al. 2011) is decision support software incorporating the PERFECT (Littleboy et al. 1992) water balance model, developed to assess the impacts of different land uses, soil conditions, management practices and climate-types on water balance and water quality. HowLeaky has been developed over the last 10 years by scientists from the Department of Environment and Resource Management (DERM), with limited funding from state, interstate and federal sources. It is currently being used by a range of Queensland Government scientists and private consultants, and is a key tool in Queensland’s Reef Rescue Project.

HowLeaky has been developed to rapidly provide reliable and flexible results from limited input data for a wide range of land use studies. It is highly suited for benchmarking and comparison of land use practices and exploring and highlighting the impacts of changing key variables on the system response. Recent modifications to the model have included the addition and refinement of pesticide, phosphorus, nitrate and solute model components.

One of the key strengths of HowLeaky is its advanced graphical user interface that provides instant visualisation and comparison of results through customisable reports and times-series analyses. HowLeaky provides users with a unique insight into land-use parameter interactions through highly graphical and interactive analyses and rapid simulation times. That is, users can change input parameters and instantly see and explore the system’s response. The simplicity of this interface promotes its use to an audience outside of the traditional modelling community providing a focus on exploring the science rather than fighting the software.