September 11th - Ocmulgee River Lab (Elevation, Clams, and Flow Rate)

During our lab at the Ocmulgee River (image below), we took measurements to determine the elevation of the river, we took samples of clams to see where in the river clams preferred to burrow, and we calculated the flow rate of the river in three places. 

Here is a Google Earth image of where we worked and took measurements. The pink transect line is the line on which we took elevation measurements and the three pointers indicate where we dug for clams.

1) Determining the Elevation: 

We used measurements from two poles connected by a string to gather the changes in elevation along the river bed. The string between the poles had a "line level" on it to indicate when the string was flat and the two poles had matching gradations (0, 1, 2, 3, 4, 5, 6) that the string lined up to. The distance between the poles at all times was 10ft. The change in elevation was reflected by how many gradations the string was different on either pole. We calculated the elevation by subtracting the first pole's number from the second's and uphill was signified by a negative number. Here is the graph of the elevation of the Ocmulgee River:

2) Clam Samples:

After the elevational measurements, we took samples of sand from near the river bank and then sand from the river channel and tried to determine where in the river clams prefer to live. We took numerous sample collections by digging up sand and placing it in a sifter. After running water over the contraption to get the sand out, only clams, rocks, and other debris too big to pass through the material were left. Out of all of our samples, clams were more abundant in the actual river channel as opposed to the sand, so we determined that clams prefer to live in the river channel. 

3) Flow rate:

The last experiment we did at the river was determining the flow rate of the water. To do this, we set up a group of people in two different points along the river. The group upstream had an old plastic water bottle and dropped it in the water and signaled the other group to begin timing. Once the bottle reached the downstream group, they stopped the timer. To calculate the flow rate, we used this experiment and the equation: DISTANCE/TIME.