O'ROURKE, Jamie; RAVELLA, Mike; LANCE, Don; SMITH, Michael; GRUNEAUR, Andrea; STILES, Todd; MARTIN, Judith; ALLEN, Timothy T.; VILLANOVA, Jeff; and DROBAT, Patricia, Geology Dept., Mailstop 2001, Keene State College, Keene, NH 03435-2001,

Recharge to groundwater aquifers is a highly dynamic process, driven by the infiltration of precipitation and influenced by evaporation and transpiration, all of which are highly variable in both time and space, over several different time and length scales. These dynamics make quantification of recharge rates and delineation of recharge areas difficult. We have undertaken a variety of field studies to assess these dynamics and better understand sub-surface hydrologic processes, within stratified drift and alluvial deposits in Keene, New Hampshire.

We have monitored water table elevation and hydraulic head above and below the water table, and calculated vertical head gradients to identify recharge or discharge conditions. We also observed changes in head in response to diurnal and seasonal variations in evapotranspiration, as well as to precipitation events. We monitored soil moisture contents in winter and determined that some infiltration does occur even under frozen conditions. Limited chemical analyses so far show no regular changes in the composition of groundwater in response to these hydrologic dynamics. Stable isotopes in the water, however, may be more effective tracers of these dynamics than chemical parameters.

ground water, recharge, infiltration, soil moisture, evaporation

1998 Geological Society of America Abstracts with Programs vol. 30, no. 1, p. 64