The objective of the Specialist Group is to address and promote all aspects of modelling, simulation and the formal methods of applying systems analysis to managing and improving the quality of the aquatic environment. This includes the development and application of mathematical models and modelling tools such as optimisation algorithms, time-series analysis and forecasting, computational procedures for decision analysis and support, uncertainty analysis… It hereby stimulates transfer of knowledge between academia and industry and between different areas within the water cycle. The Group is also responsible for maintaining a forum for the discussion of inter-disciplinary issues within the IWA to augment the engineering and economic elements of problem-solving with those having human, institutional, and cultural dimensions to them. The Group is also directed, therefore, at developing and promoting the application of systematic procedures of Integrated Assessment.