A multi-cell, lumped parameter model is also known as Tank model for regional groundwater flows. It has the advantage of being computationally very efficient, and is particularly useful / needed when data available is limited. The aquifer is divided into Tanks or cells within which the average values of the groundwater levels is assumed to be representative in the Tanks. For each Tank the mass-balance equations expressing the conservation of water are written.

The figure below shows a four-cell aquifer model. The width of the aquifer strip is 3000 m. The length of each cell is 5000 m. The natural replenishment of the aquifer strip is 400 mm/yr, 300 mm/year, 300 mm/yr, and 200 mm/yr in cells 1, 2, 3, and 4, respectively. The water level in the river is maintained at a constant elevation.

Find the steady-state head in each cell relative to the river elevation using an analytical approach. Solve the problem using MAGNET and compare the results.

MAGNET/Modeling Hints:

• Use ‘Synthetic mode’ in MAGNET to create a model domain. Resize the domain to be approximately the same size as the study area shown in the figure.
• Add prescribed head line feature along the left edge to represent the river. 
• Use zone features to differentiate the natural replenishment to each model cell.