Modern hydrogeological research uses numerical modelling, which is most often based on the finite difference method (FDM) or finite element method (FEM). The present paper discusses an example of application of the less frequently used FEM for simulating groundwater circulation in the vicinity of the intake at Świniarsko near Nowy Sącz. The research area is bordered by rivers and watersheds, and within it, two well-connected aquifers occur (Quaternary gravelly-sandy sediments and Paleogene cracked flysch rocks). The area was discretized using a Triangle generator, taking into account assumptions about the nature and density of the mesh. Rivers, wells, an irrigation ditch and infiltration of precipitation were projected onto boundary conditions. Conditions of groundwater circulation in the aquifer have been assessed based on a calibrated model, using water balance and a groundwater level contour map with flow path lines. Application of the program based on FEM, using smooth local densification of the discretization mesh, has allowed for precise mapping of the location of objects that significantly shape water circulation.
This paper presents the application of the simulation-optimization approach to optimize groundwater intake for the water supply of Tarnów agglomeration (southern Poland). Tarnów agglomeration is supplied with water from extensively exploited surface and groundwater intakes located at the confluence of the rivers Dunajec and Biała. Groundwater intakes capture water from the Quaternary aquifer, which is recharged by rainfall and direct infiltration from the rivers and irrigation ditches. Hydrogeological conditions occurring within the area under consideration were mapped by using a single-layer numerical model in Processing Modflow software. After calibrating the simulation model, a simulation-optimization approach was developed with the aim of aiding the process of searching for the best scheme of exploitation of groundwater intake. The unit response matrix method was used to connect the simulation model with the optimization procedure. In the optimization task the objective functions concerning the total volume of groundwater intake discharge and infiltration amount from the River Dunajec or irrigation ditches were applied. Several constraints concerned both the maximum and minimum capacity of individual wells and the entire intake, as well as desirable or undesirable drawdown values in selected control points and control areas. Finally, twelve variants of optimization tasks, for different boundary conditions and different objective functions, were solved and optimal schemes of well discharge distribution within the intake were calculated. The results of optimization show that, depending on the intended objective and the constraints imposed, the best exploitation scenario under the given conditions may be found.