HR: 14:00h
AN: H23A-01    [Abstracts]
TI: Characterization and Ground Water Management of two Rural Water Supply Sources in Kentucky and Illinois.
AU: * Boateng, S
EM: boatengs@nku.edu
AF: Northern Kentucky University, Physics and Geology Dept., Highland Heights, KY 41099, United States
AB: Ground water flow and particle tracking simulations were performed to characterize ground water flow trends in two aquifers that serve as water supply sources for two rural communities in Kentucky and Illinois respectively. The objective was to evaluate ground water management issues related to well head protection and the potential of increasing withdrawal rates in high-yield wells to meet future demands in water supply. Also, the water quality implications of potential increases in yield were analyzed. The impact of future expansion of residential developments and sewage disposal systems on the migration of contaminants into the aquifer was considered. The aquifers mainly are composed of sand and gravel overlain by clay and silt sediments. Well log data and ground water measurements of the alluvial aquifer in western Kentucky indicated that it is semi-confined and can be as thick as 80 feet in most areas. The alluvial aquifer in south central Illinois essentially is unconfined with an average thickness of about 70 feet. The U.S. Geological Survey computer codes MODFLOW and MODPATH were used for all the model simulations. For the aquifer in Kentucky, the Ohio River formed the western boundary of the model area with the bluffs in the eastern part being modeled as a flux boundary. For the aquifer in Illinois, the Illinois River formed the eastern boundary with the bluffs in the western boundary serving as a flux boundary. An unconfined conceptual model and a two-layer unconfined/semi-confined model were considered. The observed field ground water levels matched the latter model better for the alluvial aquifer in Kentucky. However, a one layer model was best suited for the aquifer in Illinois. The sensitivity of hydraulic conductivity, river conductance and recharge to the flow simulations were performed. Capture zone and areas of recharge were demarcated for each aquifer. Withdrawal rates of existing wells were increased to mimic increased future water supply. The resulting increase in drawdown did not cause excessive decrease in ground water storage nor drawdown, even under persistent drought conditions. Drought conditions were simulated with no recharge and low rive pools. Also, there was a little but insignificant increase in the capture zone as a result of the increase in the withdrawal rates. Under excessive recharge conditions (flooding), the rise of ground water with each aquifer was about 20 feet below ground surface. Thus, areas with outcrops of sandy material rather than silt and clay may be more vulnerable to surface and near-surface contaminant sources. This is particularly important at locations where new subdivisions could introduce contamination via septic systems. These rural areas do not have sewer treatment facilities. Additional observation wells are needed to characterize the two aquifers better.
DE: 1829 Groundwater hydrology
DE: 1831 Groundwater quality
DE: 1847 Modeling
DE: 1880 Water management (6334)
DE: 1884 Water supply
SC: Hydrology [H]
MN: 2007 Joint Assembly