Characterizing Heterogeneous Groundwater Discharge in the Headwaters of the White River, Manistee National Forest, Michigan
Abstract:
Characterizing groundwater flow through a heterogeneous aquifer faces many difficulties arising from the inability to directly observe groundwater flow. By measuring the physical and chemical characteristics of the groundwater-surface water interaction at the headwaters of the White River in Manistee National Forest, Michigan, the dynamic nature of the aquifer can be better understood. Groundwater discharge into the stream occurs as both diffuse contributions and through conduit-style (springs) discharge areas located in a small section (~100m2) of the headwaters. There are about a dozen springs located in the streambed, with a few of the springs appearing to turn on/off or shift locations. Discharge from these springs was measured using two personally-constructed seepage meters. Using low-profile seepage meters designed with the assistance of Don Rosenberry of the USGS, four of the springs were found to have an average discharge of 2.5 x 10-3 cm/s, while diffuse discharge ranged from 1.7 x 10-7 to 1.4 x 10-4 cm/s. Stream discharges have been measured using an electromagnetic flow meter along one transect just downstream from the springs, and will be measured at another slightly upstream.Previous work in the area has been focused on long-term monitoring of the aquifer and attempts at mapping groundwater discharge using thermal imaging. In addition to discharge measurements, water levels in piezometers in the recharge zone and the confining wetland have been logged since 2008. Water quality measurements (pH, temperature, conductivity) of both discharging groundwater and stream water were also taken. Current research on the area is focused on analyzing samples of snow, groundwater and stream flow for stable isotopes of oxygen and hydrogen to better understand aquifer contributions to stream baseflow. By using all of these different techniques, researchers ultimately hope to better understand the influence of groundwater on streamflow in order to help the Forest Service better manage this natural resource.