HOW DOES GRAIN SIZE VARY ON THE FLOOD PLAIN?

Variability of sediments in the floodplain in the Ronald R. Rhein Environmental Study Area in Kutztown, PA, occurs both in the easterly and westerly directions. The area studied was a distance of 360 meters moving downstream from the original survey section. Core samples of the sediments were taken approximately 2 feet down and were put into plastic bags that were labeled with the location downstream and distance from the stream channel in either the east or west direction. This was done every 5 meters from selected locations up to 15 meters away from the stream channel both east and west. Field location 1 was 90 meters away from field location 2 the same for locations 3 and 4. We found out that the floodplain was a bimodal system. On the eastern side of the stream, the grain size was slightly heavier in the smaller grains. This now indicates that a different process, such as sheet wash from the farm located uphill from the eastern side of the stream, is the driving force behind the grain transport. On the other side, the driving force was mostly the stream.