HR: 0800h
AN: H21A-0190    [Abstracts]
TI: Innovative Springshed Mapping for Trout Stream Management
AU: * Luhmann, A J
EM: luhm0031@umn.edu
AF: University of Minnesota, Department of Geology and Geophysics, 310 Pillsbury Drive SE, Minneapolis, MN 55455, United States
AU: Alexander, S C
EM: alexa017@umn.edu
AF: University of Minnesota, Department of Geology and Geophysics, 310 Pillsbury Drive SE, Minneapolis, MN 55455, United States
AU: Alexander, E C
EM: alexa001@umn.edu
AF: University of Minnesota, Department of Geology and Geophysics, 310 Pillsbury Drive SE, Minneapolis, MN 55455, United States
AU: Green, J A
EM: jeff.green@dnr.state.mn.us
AF: Minnesota Department of Natural Resources, Division of Waters, 2300 Silver Creek Road NE, Rochester, MN 55906, United States
AB: Springs in the Paleozoic karst lands of southeastern Minnesota provide water to trout streams, whose existence depends on a steady supply of clear, cold water. 14 Minnesota springsheds or recharge areas of the source springs have been mapped by dye tracing over the past three decades. The boundaries of these springsheds bear little resemblance to surface watershed boundaries. However, dye traces are time and labor intensive. The 14 defined springsheds represent only 8% of the 173 designated trout streams in southeastern Minnesota. Water management associated with the increasing human impacts of intensive agriculture, new water demands, climate change, and landscape alteration requires more efficient means of defining the remaining springsheds. Methods are being investigated to improve the efficiency of dye tracing. We are also investigating alternative methods of defining springsheds. One promising method combines gamma logs of a few water wells with conventional drilling logs to construct detailed structural contour maps. Conduits present in southeastern Minnesota karst systems generally run parallel to the local, sub-horizontal bedding planes, and multiple joint systems enable water to move down-dip within and along local bedrock units. Another method uses temperature and conductance loggers to augment conventional spring hydrographs. Comparison of spring thermo- and chemo-graphs allows better hydrograph separation. This refined hydrograph analysis allows improved estimates of basin size and connectivity. Additional methods involve the use of major element chemistry and stable isotopes of hydrogen and oxygen in combination with pre-existing water quality data to look for seasonal influxes of recharge water. The results of these alternative methods can then be compared with new and pre-existing dye trace results to gauge their effectiveness in delineating springsheds. The integrated use of a variety of hydrogeologic tools allows a better understanding of these highly dynamic karst systems.
DE: 1829 Groundwater hydrology
DE: 1880 Water management (6334)
DE: 1884 Water supply
SC: Hydrology [H]
MN: 2007 Fall Meeting