Experiment No. 1

For this experiment, 3 wells were fastened to the inside of the front Plexiglas sheet using silicone sealant. This was done before the model was assembled.

The wells are lengths of vinyl tubing with open ends. Filter material was inserted into the lower end of each tube to prevent sand from entering the wells.

The "T" in the discharge tube was raised to its upper limit, such that the model filled with water. The water supply was then turned off. With the horizontal water table that soon became established, there is no hydraulic gradient and no horizontal flow of water through the model.

Red food coloring was added to the 2 outer wells.

This is the initial state of the model for this experiment.

Water was drawn from the center well using a basting bulb. Immediately after drawing the water, drawdown was observed in the 2 outer wells. During drawdown, red dye issued from the bottoms of the 2 outer wells and migrated toward the center well. Migration of the dye was driven by the horizontal gradients toward the center well.

For the duration of the experiment, water was drawn from the center well every few minutes.

At 6 minutes, the dye had migrated nearly half way to the center well.

At 10 minutes into the experiment, the dye had migrated most of the way to the center well.

Photos for t=6 minutes and t=10 minutes were taken shortly after drawing water from the center well. Note the drawdown in the 2 outer wells.

At 27 minutes into the experiment, the concentration of dye in the center well was nearly the same as that of the 2 outer wells, as judged by the coloration.

Note that photos for t=18, 25, and 27 minutes were taken after drawdown had recovered.