Support of the Generic Framework programme : calibration of groundwater flow models

Abstract

This report is to support the “Generic Framework programme” which consists of a series of projects to create a standard in the modelling processes that are used in water management issues. The topic of support is the field of model calibration. TNO-NITG is elaborating the calibration of groundwater flow models.

To gain insight in the geohydrological processes in space and/or time a geohydrologist makes use of numerical groundwater models. These groundwater models are based on characteristics of the subsurface and the hydrological interfaces in the top-system. However, these characteristics are not known exactly. In practice this means that the groundwater models need to be calibrated.

The goal of the research of TNO-NITG on the field of calibration of groundwater models is to produce an applicable method suitable for the use in real world groundwater management problems. The modeller needs and objective an repeatable method for calibrating groundwater models, in which all available information can be efficiently incorporated and the reliability of the data and the uncertainty of the results of the groundwater model can be quantified.

The report can be seen as a refinement of the “Handbook Good Modelling Practice” (Waveren et al., 1999) on the process of calibration. The handbook is describing requirements of a good modelling process in a more broader context. So also very important issues like defining the goal of the model, creating a basis of trust by the users by communication during the building and presenting of results are the topic of this handbook. Although we are aware of the importance of these topics in order to get a ‘good’ model, this report is focusing on the calibration proces: how is the data used, in the broadest sense, to get the best possible model.

In this report, first the vision of TNO-NITG on calibration of (groundwater) models is given in chapter 2. Chapter 3 presents a number of key issues in calibration; it describes the main line of this report. Chapter 4 describes two state-of-the art methodologies more in detail. This chapter can be skipped without losing the main line of the report. In Chapter 5 the presented key issues of chapter 2 are illustrated with a few real world examples. Finally Chapter 6 presents the key issues and the cookbook out of chapter 3 again as a summary.