Defining Groundwater Flow Characteristics in the Northern Segment of the Edwards Aquifer Based on Groundwater Chemistry


Ian C. Jones


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Publication Date

January 2006


Chemical and isotopic compositions along two groundwater flow paths were used to characterize groundwater flow system in the northern segment of the Edwards (Balcones Fault Zone) Aquifer. Groundwater compositions reflect geochemical processes that the groundwater encounters along a flow path, for example, interaction with aquifer rock or soil, groundwater mixing, and recharge processes. Recharge processes can be investigated by comparison of conservative constituents in both precipitation and groundwater. Results of this study support groundwater flow model results that indicate that (1) groundwater circulation is most active in the unconfined part of the aquifer where most of the recharge occurs by infiltration through soil and intermittent streams and natural discharge occurs through perennial streams and (2) little groundwater flow enters the confined part of aquifer. The spatial distribution of groundwater flow in the aquifer produces compositional differences between groundwater in the unconfined and confined parts of the aquifer. Additionally, this study suggests that recharge to the aquifer occurs mostly during fall and winter months. This observation is based on stable hydrogen and oxygen isotopic compositions of groundwater and precipitation.

Document Type



Austin Geological Society Bulletin, Vol. 2 (2006).