Jonathan M. Malzone
Controls on nutrient export from agricultural landscapes include regional hydrological and geological conditions. In many central Kentucky basins shallow fractured bedrock produces focused groundwater discharge and flashy runoff events. Eastern Kentucky University’s Meadowbrook Farm is currently experimenting with nutrient sequestration techniques; however the effectiveness of these techniques given the local hydrogeology needs to be quantified. Our objective was to determine the potential pathways for nutrient export by mapping key hydrologic features using a watershed approach with ArcGIS software. The key features mapped were our springs, tile drains, runoff channels, and landuse with the underlying geology. We studied the springs contained within the farm and our watershed was 0.4596923 km2 and is a good representation of the farm. Within our watershed we constructed a V-notch weir at the outlet to determine the flow from surface runoff and groundwater inputs to conduct a water budget for the watershed. Next, we installed gaging stations along a main fourth order stream that the farm drains into. Finally, we selected sites within the stream to conduct differential stream gaging to quantify the input and outputs of groundwater to the stream. By layering the local geology with the location of springs, we found that the Boyle Dolomite contained 100% of the springs. This means that groundwater recharge and discharge is controlled by the outcrop of the Boyle Dolomite. Hydrographs indicated flashy runoff events consisting of ~15% of precipitation volume. Nutrient export is confined within these flashy events. Differential stream gaging indicated both gaining and losing reaches.