Can we calibrate a complex groundwater model just by running an automatic calibration code? A case study from Italy: The Acque Albule Plain model (Rome)

This note presents a calibration of a model of a complex groundwater system located in central Italy, in the subsiding Acque Albule (AA) Plain near Rome (Italy). There are two main aquifers in this system. The first is the limestone fractured bedrock, partially confined by Pliocene-Pleistocene deposits, while the second one is within the fractured travertine and is unconfined. These two aquifers are hydraulically connected in correspondence of the centre of the plain, where deep hydrothermal water upwells from the limestone bedrock through the Plio-Pleistocene deposits into the travertine. The AA groundwater model is applied to a 55-km 2 area and is developed by using MODFLOW-2005, discretized by 100 m × 100 m cells and three layers. The calibration process applied to this model consists of several steps using estimation methods along with sensitivity analysis and geological information. The final model fit shows the importance not only of applying automatic estimation methods for calibration processes, but also the need to change the conceptual model and collect new data to understand the system better. Copyright © 2011 IAHS Press.