Highlighting the model code selection and application process in policy-relevant water quality modelling

The paper illustrates and discusses some rather simple and pragmatic means to enhance the quality of model-based knowledge input for decision-making. Firstly, we apply a stepwise description of the modelling process to describe our “case story”, in which we first define modelling objectives and then use the benchmark criteria approach to evaluate model codes and to select an appropriate model code to be set up, analysed, and applied to simulate the long-term (decades) phosphorus–phytoplankton interactions and thus the eutrophication problem in Lake Vansjø-Storefjorden, Norway. Results from the simulations with the MyLake model indicate that at least 50% reduction in phosphorus loads are needed in order to reach the strictest environmental goal in the long-term. We believe that by: (1) following (and documenting) the step-by-step modelling process outlined in this paper, by (2) using available (internet-based) inventories to get an overview of existing model codes, and by (3) performing and documenting the model code selection with help of the benchmark criteria approach, at least some of the barriers to model use in environmental management can be removed.