Evaluation of the Netherlands Groundwater Model, LGM, for calculating pathlines, travel times and concentration at abstraction wells

LGM is a numerical model (based on the finite-element method), comprising complex geohydrological system components. LGM uses spatially variable (heterogeneous) data for four aquifers covering the entire surface area of the Netherlands. The evaluation was done for both synthetic homogeneous and realistic heterogeneous field conditions. For numerical verification of LGM, use is made of the analytical solution-based computer program FLOPZ1, for homogeneous geohydrological conditions.

One of the conclusions is that a full-feature numerical spatially-distributed modelling approach, such as implemented in LGM, serves as a prerequisite for an adequate assessment of pathlines, travel times and concentration breakthrough curves.

The report emphasises the evaluation of LGM for phreatic abstractions. However, recommendations are also given for LGM's applicability to other types of groundwater abstractions. Attention has also been given to guidelines for selecting an adequate spatial resolution of the finite-element grid.