Calibration and Reliability in Groundwater Modelling: From Uncertainty to Decision Making
(Proceedings of ModelCARE’2005, The Hague, The Netherlands, June 2005). IAHS Publ. 304, 2006. pp.240–245.Uncertainty estimation of well catchments:
combined effect of inhomogeneous transmissivity and uncertain mean recharge
FRITZ STAUFFER1 & HARRIE-JAN HENDRICKS FRANSSEN2
1 Institute of Hydromechanics and Water Resources Management, ETH -Hönggerberg,
HIL G33.2, CH-8093 Zürich, Switzerland
2 Institute of Hydromechanics and Water Resources Management, ETH -Hönggerberg,
HIL G33.3, CH-8093 Zürich, Switzerland
stauffer@ihw.baug.ethz.ch
Abstract Steady-state catchments of pumping wells can be determined for equivalent parameters using various existing codes for groundwater modelling. The catchment boundary may be obtained by calculating the boundary path lines starting at a stagnation point in a reversed flow field. However, how uncertain is the result for heterogeneous aquifers and uncertain mean recharge? A method is proposed to estimate the uncertainty of the location of the catchment boundary in two-dimensional steady-state aquifers due to the combined effect of the uncertainty of the spatially variable unconditional transmissivity field and of the uncertain mean areal recharge rate. The former is based on the semi-analytical first-order theory, which allows estimates of the lateral second moment (variance) of the location of a moving particle. The method allows post-processing of results from groundwater modelling with respect to uncertainty estimation. In order to test the methodology it is compared with results from Monte Carlo simulations.
Keywords
groundwater; protection zones; spatial variability; uncertainty estimation