Development of a digital model of ground-water flow in deeply weathered crystalline rock, Indian Creek area, North Carolina
- Geological Survey, Raleigh, NC (United States)
The digital ground-water model of the regolith-bedrock aquifer system in the Indian Creek area is based on the US Geological Survey's modular finite-difference ground-water flow model (MODFLOW). Use of MODFLOW assumes porous media equivalence; however, special approaches have been used to account for non-uniform fracture distribution. The model is divided into a uniformly spaced grid having 196 rows, 140 columns, and a 500-foot spacing. Rows are oriented parallel to fractures (N 72 E) and columns are oriented parallel to foliation (N 18 W). The area represented by active model cells is 146 square miles and has about 17,400 cells. The model has 11 layers of different thickness; the top layer represents the regolith and the lower 10 layers represent bedrock. The regolith-bedrock contact is at a uniform depth of 50 feet. The base of the model is 850 feet below land surface. Hydraulic properties of regolith are based on diffusivity calculated from streamflow recession and are assumed to be areally constant. The steady-state model simulates recharge to, flow through, and discharge from the regolith-bedrock aquifer system. The mass balance between inflow and outflow differs by less than 1%. Along select sections, computed travel times from drainage divides to streams range from less than 4 years in the regolith to as much as 300 years for flow passing through the bottom layer of bedrock. The volume of ground water that flows through the bottom layer is only about 2% of the flow through the regolith.
- OSTI ID:
- 6793138
- Report Number(s):
- CONF-9404221-; CODEN: GAAPBC
- Journal Information:
- Geological Society of America, Abstracts with Programs; (United States), Vol. 26:4; Conference: 43. annual meeting of the Southeastern Section of the Geological Society of America, Blacksburg, VA (United States), 7-8 Apr 1994; ISSN 0016-7592
- Country of Publication:
- United States
- Language:
- English
Similar Records
Modeling of ground-water flow in subsurface Austin Chalk and Taylor marl in Ellis County, Texas, near the superconducting super collider site
Modeling recovery well capture zones in a fractured bedrock aquifer: An application of the analytic element method