Quantifying the impact of model inaccuracy in climate change impact assessment studies using an agro-hydrological model

摘要

Numerical simulation models are frequently applied to assess the impact ofclimate change on hydrology and agriculture. A common hypothesis is thatunavoidable model errors are reflected in the reference situation as well asin the climate change situation so that by comparing reference to scenariomodel errors will level out. For a polder in The Netherlands an innovativeprocedure has been introduced, referred to as the Model-Scenario-Ratio(MSR), to express model inaccuracy on climate change impact assessmentstudies based on simulation models comparing a reference situation to aclimate change situation. The SWAP (Soil Water Atmosphere Plant) model wasused for the case study and the reference situation was compared to twoclimate change scenarios. MSR values close to 1, indicating that impactassessment is mainly a function of the scenario itself rather than of thequality of the model, were found for most indicators evaluated. A climatechange scenario with enhanced drought conditions and indicators based onthreshold values showed lower MSR values, indicating that model accuracy isan important component of the climate change impact assessment. It wasconcluded that the MSR approach can be applied easily and will lead to morerobust impact assessment analyses.