An automatic sampler station consists of a bubble flow meter and a sampler. A bubble flow meter performs two functions. First, it contains an air pump that is attached to a plastic tube. This tube runs from the bubble flow meter to the river bottom. Air is pumped through the plastic tube and the pressure needed to do this is recorded. As the pressure needed to pump air through the tube rises, the bubble flow meter knows that the level of the river is also rising. When the river rises to a certain level, the bubble flow meter sets off the automated sampler to take a fixed amount of samples. To do this, the sampler uses a peristaltic pump to create a vacuum. This vacuum is powerful enough to lift water from a river that is over 25 feet away. The water is separated into small samples by the pump and then placed in bottles inside the sampler by a rotating arm.

The bubble flow meter's second function is to record rainfall. A tipping-bucket rain gauge is attached to the bubble flow meter by an electrical line. Rain comes into a funnel on the top of the rain gauge, and goes into a bucket that is on the upside of a small teeter-totter. When one-hundredth of an inch is in the bucket, the teeter-totter swings down, releases the water, and creates an electrical pulse that is sent and recorded by the bubble flow meter. Each electical impulse represents one-hundredth of an inch of rain. The bucket on the other side of the teeter-totter, which is now on the upside, starts to fill with water and the process starts over again.

July 15, 1998
Dennis Hoffman, Project Leader
Steve Dagitz, Webmaster