Numerical modelling plays an important role in the design of proposed development projects including quantitative assessment of their potential impacts. Whether a proposed development implies physical, chemical or biological ‘footprints’ in the aquatic environment, the development of more reliable and user-friendly models have made it easier and more economically feasible to assess the effects and to separate natural fluctuations from actual impacts.

The application of models assists decision makers in many different ways. For example:

• in site selection and evaluation of its appropriateness for a given purpose
• through assessment of design conditions as basis for dimensioning structures, etc
• by isolating and reducing uncertainty with respect to anticipated environmental changes
• through evaluation of different layouts or scenarios of measures ensuring that the most (cost-) effective layout or approach is adopted

Also for operational and planning purposes, numerical models are indispensable tools in decision making. For example, using integrated monitoring and modelling systems to simulate the conditions in real time and make predictions, typically few days ahead, for:

• Emergency planning and disaster management, eg flood forecasting or clean-up assessments related to accidental spills
• Optimisation of reservoir operations
• Water quality control - forecast of water quality eg bathing water (public health purposes) or in aqua farming for optimisation and protection of production, etc