USING SHORT LIVED RADIONUCLIDES AND X-RAY DIFFRACTION TO EXPLORE THE EFFECTS OF AGRICULTURAL DRAINAGE TILES ON DEPTH OF EROSION IN THE VERMILION WATERSHED, NORTHERN OHIO

This study looks at the relationship between agricultural land use, drainage tiles and depth of erosion in the Vermilion watershed in Northern Ohio. We use Cs-137 gamma spectrometry and Powder X-Ray Diffraction to track the movement and relative weathering of sediments. Land use in the Vermilion watershed is primarily agricultural and many farmers use drainage tiles to combat the effects of compacted and clayey soil. Drainage tiles are installed 3-6 feet below the ground surface and direct water from fields to ditches, streams and other channels. Their use has been a common practice for decades in the Midwestern United States. Researchers in Europe have studied the impact of drainage tiles on the nature of erosion within catchments, but similar analysis does not appear to have been done in the United States and despite their widespread use, the effects of drainage tiles on erosion are not yet fully understood. This study analyzes 26 samples collected in the Vermilion River watershed in Erie, Huron and Lorain counties. Cs-137 is a ‘man-made’ fallout radionuclide generated by nuclear weapons testing from the mid 1950s to early 1970s, and can be used to trace the movement of soils and sediments. Using a germanium detector, we measured concentrations of Cs-137 to look for correlations between location of drainage tiles and Cs-137 activity. We modeled drainage tile distribution based on land use and soil drainage properties. We then completed a correlation analysis of Cs-137 activity in detrital sediments and the percentage of the upstream watershed drained by tiles. Our preliminary results indicate that the correlation may not be as strong as we had predicted. This study also uses X-Ray Diffraction techniques to determine what, if any, effect the drainage tiles have on the minerals present and composition of minerals in the sediments. With this analysis we hypothesize that surface erosion will be correlated with more weathered minerals while deep erosion will be shown with less weathered minerals. Understanding drainage tiles could give us information about top soil loss. It also may be that drainage tiles widen channels and increase sediment in the river as well as change the hydrology of the watershed so that the hydrograph goes up and down more rapidly during and after storms.

Acknowledgements: Joseph Martin, Yue Qiu, Arianna Goodman