Geology topics

R.H. Cobb

Publications and source records attributed to R.H. Cobb.

3 recordsLinked to original sources

USGS1988

Geohydrology and susceptibility of major aquifers to surface contamination in Alabama; area 12

This report delineates and describes the geohydrology and susceptibility of major aquifers to contamination in Coffee, Dale, Henry, Houston, and Geneva Counties, Alabama. The major aquifers are the Upper Floridan, Lisbon, Nanafalia-Clayton, and Providence-Ripley aquifers. Estimated groundwater withdrawals for public water supplies are about 42 million gal/day. Maximum withdrawals for irrigation are 15 to 20 million gal/day. Withdrawals for self-supplied industrial and domestic uses are estimated to be 3 and 2.5 million gal/day, respectively. Long-term withdrawals of water from the Nanafalia-Clayton aquifer have resulted in significant declines in the potentiometric surface in Coffee, Dale, and Houston Counties. Significant declines in the potentiometric surfaces of the other major aquifers are not apparent. Recharge areas for all major aquifers are susceptible to contamination, but the probability of contamination of the Lisbon, Nanafalia-Clayton, and Providence-Ripley aquifers is low because the recharge areas are remote from areas of withdrawal. The recharge area for the Floridan aquifer, which consists largely of flat, sandy farmland , coincides with the area of use. This area is highly susceptible to contamination from insecticides and herbicides. (USGS)

Water-Resources Investigations Report↗

USGS1987

Geohydrology and susceptibility of major aquifers to surface contamination in Alabama; Area 8

The U.S. Geological Survey, in cooperation with the Alabama Department of Environmental Management, is conducting a series of geohydrologic studies to delineate the major aquifers and their susceptibility to contamination in Alabama. This report delineates and describes the geohydrology and susceptibility of the major aquifers to contamination in Area 8--Autauga, Chilton, Elmore, Lowndes, and Montgomery Counties. The major aquifers in the study area are the Eutaw, Gordo, and Coker aquifers of Cretaceous age. One or more of these aquifers are sources of public water supply in each of the five counties. The recharge areas for these aquifers are in Autauga, Chilton, Elmore, and Montgomery and Prattville. Maximum groundwater use in the Prattville area is more than 8 mgd (million gallons per day). Estimated maximum groundwater withdrawal for all uses in the study area is about 65 mgd. The potentiometric map of the Gordo aquifer indicates that the Alabama River may serve as a recharging boundary to the Gordo aquifer along the flood plain of the river in the Montgomery-Prattville area. The river also is acting as a recharging boundary to the Eutaw and Coker aquifers, where the potentiometric surfaces in the aquifers have been lowered. All recharge areas for the major aquifers are susceptible to contamination from the surface. However, the areas that are highly susceptible to contamination extend from Jemison to Clanton in Chilton County where the Coker aquifer generally is < 100 ft below land surface, and the flood plains of the Alabama, Coosa, and Tallapoosa Rivers, which are underlain by alluvial deposits that are in hydraulic contact with the major aquifers. Within the highly susceptible areas, the areas especially susceptible to contamination are the flood plain of the Alabama River in the Montgomery area and the flood plain of the Tallapoosa River. Pumpage from the major aquifers in this area has significantly lowered the potentiometric surface in the aquifers resulting in a downward gradient between the major aquifers and the Alabama River and the alluvial deposits underlying the flood plain along the river. (Lantz-PTT)

Water-Resources Investigations Report↗

USGS1987

Geohydrology and susceptibility of Coldwater Spring and Jacksonville fault areas to surface contamination in Calhoun County, Alabama

Coldwater Spring in eastern Calhoun County, Alabama, is one of the largest springs in Alabama. The spring, which has an average discharge of about 31 million gallons per day, supplies water for about 70,000 people in the Anniston, Alabama area. A potentiometric map of the study area indicates that the recharge area for the aquifer system that supplies the spring is only about 23 square miles. However, base-flow data for streams in the area indicate that this recharge area is not sufficient to account for an average discharge of 31 million gallons per day from Coldwater Spring. Complex folding and faulting of the carbonate and quart zitic rocks that comprise the aquifer system may have produced fractures and joints that increase recharge to the spring. Some recharge to the spring may be derived from outside the recharge area delineated from the potentiometric map or from the surface. This part of the recharge area contamination from the surface. This part of the recharge area consists of flat to gently rolling terrain underlain by cavernous limestone and fractured quartzite. (USGS)

Water-Resources Investigations Report↗