Scientific comparison of water quality models

A unique scientific comparison of hydrological models to assess water quality is being carried out. The primary aim of the international study is to increase knowledge on uncertainties in model-based decision support.

In the first part of the evaluation, modelled values was compared with measurements. It also considered conclusions for decision-makers, based on calculations of various management scenarios for reduced eutrophication. 
The second part focuses on the use of the models and on developing guidelines. Representatives from municipalities, county administrative boards, water authorities, environmental protection agencies and others will discuss issues related to decision-making in spite of uncertainties.

Projecting and managing uncertainties

“We will of course learn more about the models during the comparison, and the uncertainty that is caused by model structure and set-up assumptions,” says Berit Arheimer, hydrology scientist at SMHI.

“One important question is whether the average result from several water quality models is better than the best model individually, as we find this kind of result for water discharge. If so, we would recommend the use of several models in decision-support.”

Overall focal points for the evaluation will be to communicate to users how the model results can be applied, to increase the degree of understanding and acceptance for models, but also how uncertainties can be calculated and managed.

Seven models compared

Around 20 participants from five countries contribute to the evaluation. The seven models covered by the study are used both internationally and in Sweden by institutes, consultants and universities on request by e.g. water authorities. SMHI is contributing with two models: the HBV-NP and the HYPE. 
The ‘Nutrient model comparison’ workshop is being organised by the International Hydrological Programme (IHP), which is an intergovernmental scientific programme focusing on research into water-related issues.