English Abstract Within the framework of the preparation of the Dutch
National Policy Plan for Drinking and Industrial Water Supply, the RIVM
Groundwater Model for the Netherlands (LGM) is developed. The main goal of
the study was to elaborate upon the effects of groundwater abstraction on
terrestrial ecosystems (not considered in this report). LGM is used to
assess the effect of changes in groundwater abstractions upon the
geohydrological system. The effect is expressed in terms of hydrological
variables, namely the changes in phreatic waterlevel, groundwater head in
deeper aquifers, flux between the upper boundary of the geohydrological
system and the top aquifer, and fluxes across the aquitards. Several types
of groundwater abstractions were distinguished, namely abstractions from
phreatic aquifers, semi-confined aquifers, and riverbank infiltration. In
eight scenario's, the yearly amount of groundwater was increased or
decreased, with respect to the reference groundwater abstractions occurred
in 1988. LGM is a coupled system of so-called AQ-computer program packages
(e.g.AQ-FEM) and a Geographic Information System (GIS). The main task of
the GIS-environment is the storage, processing and visualisation of
spatially data, including the moddelling results. The AQ-computer programs
are based on the numerical technique of finite elements. The saturated
multi-aquifer geohydrological system consists of a series of aquifers
separated by aquitards. The flow in the system is assumed to be quasi
three-dimensional.
