HR: 1340h
AN: H13G-1665    [Abstracts]
TI: Geologic and Hydrologic Controls on Denitrification in Denitrifying Layer-Bearing Groundwater Systems at Watershed Scales
AU: * Wang, M
EM: mingyuwpan@yahoo.com
AU: Wang, J
AU: Chen, H
AB: Nitrate contamination of ground water from agricultural practices may degrade groundwater quality and contribute to the eutrophication of surface water. Field evidence and geochemical analysis indicate removal of nitrate by denitrification in denitrifying layers (redox zones) situated in groundwater systems. The potential for denitrification in the denitrifying layers may considerably impacted nitrate levels in the aquifers and, in turn, the streams of the pertinent watersheds. Denitrification in the aquifers may be influenced by different geologic and hydrologic factors such as extent and thickness of the denitrifying layer below the watersheds, hydraulic conductivity of the geologic formations, and the regional dip of the underlying strata. In this study, groundwater flow and nitrate fate and transport are modeled, by using a powerful computer modeling package, in the regional aquifers beneath the agricultural watersheds at a specific site. The groundwater flow and nitrate fate & transport numerical models were calibrated and verified successfully by implementing an integrated modeling approach. The models simulated a significant reduction in long-term nitrate loading into the streams from the agricultural practices due to denitrification in aquifer sediments. Sensitivity analysis through numerical simulations has been performed to investigate the relative significance of various geologic and hydrologic factors possibly influencing denitrification in aquifers. The interesting modeling findings have been achieved from this investigation that may have implications on the effective controls of nitrate contamination of groundwater and surface water systems in watershed scales.
DE: 1800 HYDROLOGY
DE: 1831 Groundwater quality
DE: 1832 Groundwater transport
DE: 1847 Modeling
DE: 1871 Surface water quality
SC: Hydrology [H]
MN: 2007 Fall Meeting