Calibration and Reliability in Groundwater Modelling: Credibility of Modelling

(Proceedings of ModelCARE 2007 Conference, held in Denmark, September 2007). IAHS Publ. 320, 2008, 295-298.

Transient calibration of flow to ditches with entry resistance using measured moments of response functions

MARK BAKKER^1,2, KEES MAAS^1,2 & jos VON ASMUTH^1,2

1 Water Resources Section, Faculty of Civil Engineering and Geosciences, 2628 CN Delft University of Technology,
2628 CN Delft, The Netherlands

markbak@gmail.com

2 Kiwa Water Research, 3430 BB Nieuwegein, The Netherlands

Abstract A comprehensive and efficient approach has been developed for the calibration of transient groundwater models. The new approach is explained through application to a problem with two observation wells with 4 years of weekly head data. The wells are located between two long ditches. Unknown aquifer parameters are the hydraulic conductivity, the storage coefficient, and the entry resistances of the ditches. The approach starts with a time series analysis of the heads using the PIRFICT method, which results in the first two temporal moments of the impulse response functions at the two observation wells. Both these moments fulfil differential equations that are equivalent to the differential equation for steady groundwater flow. Models of the moments are calibrated against the values obtained from time series analysis to determine the unknown aquifer parameters. The proposed calibration process for transient models performs well and only requires the calibration of two steady models, while measured head data is taken into account in a comprehensive fashion.

Key words transient model calibration; time series analysis; moment matching