Saturday, May 11, 2013

Hooghoudt auger hole method

Being in Holland we use bikes for transport, even if we need to bring some heavy equipment. Our excellent mechanical university workshop produced some cart that are great in use, even on the sandy roads that we use in this course.

Bicycles packed and ready to leave on a cold day at Camping Meuleman in  Twente

A method that makes students nervous is always nice to teach. In this case it requires teamwork and fast reaction as the whole experiment is over in about 10 seconds. We measure the hydraulic conductivity (or permeability of the soil for water) with three methods. The first one is by the ring infiltrometer. This is a nice a method which does not require eagle eyes or fast reaction as the "bubbles" that need to be recorded are quite slow leaving students time to mull over the meaning of life and other irrelevant questions.

Thomas and Anne reading a Mariotte bottle during a ring infiltrormeter test

Asta and Patricia in action on the Dinkle river beach under close supervision of Robbert
This is not so for the method with the unpronounceable Dutch name, no time to think at all, just rapid action. This is a test where some water is pumped out of a filter installed in the saturated zone. As this beach is sandy, water will flow in fast and the rise of the water level that needs to be measured with a divice as simple as it is ingenious. Here you see Robbert bailing out water from the well, while Asta holds the measuring tape, Anne is ready to write, Thomas has the stopwatch and Patricia was just too cold to do anything but shiver.

Start of the action, all is relatively calm at this stage
Asta reading the measuring tape every two seconds while Anne writes things down.
After a failure in communication during the first try (happens always) the other attempts were all succesful and the data is in. Later more about the pumping test...

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