When is a groundwater model considered calibrated?

A groundwater model is considered calibrated when hydraulic heads and fluxes reproduce the system modeled within an acceptable tolerance. Calibration involves adjusting model parameters until the model outputs closely align with observed data under the same conditions. This ensures that the model accurately represents the groundwater system's behavior, encompassing variations in water levels and flows across different scenarios, such as pumping tests or natural recharge events.

While accurate future predictions and reflecting seasonal variations are important aspects of a functional model, they are not the main criteria for calibration. Moreover, matching historical data perfectly is often unrealistic due to the inherent complexities and heterogeneities of groundwater systems. Calibration aims to achieve a balance between fitting the observed data and allowing for reasonable predictions, hence the focus on acceptable tolerance rather than perfect accuracy.