Search USGS⌕ Search

Geology topics

H. F. Grubb

Publications and source records attributed to H. F. Grubb.

7 recordsLinked to original sources
USGS2001

Ground-water flow in the Gulf Coast aquifer systems, south-central United States

The Gulf Coast regional aquifer systems constitute one of the largest, most complicated, and most interdependent aquifer systems in the United States. Ground-water flow in a 230,000-square-mile area of the south-central United States was modeled for the effect of withdrawing freshwater at the rate of nearly 10 billion gallons per day in 1985 from regional aquifers in the Mississippi Embayment, the Texas coastal uplands, and the coastal lowlands aquifer systems. The 1985 rate of pumping was three times the average rate of recharge to the aquifers before development. The report also estimates the effects of even greater withdrawal rates in the aquifer systems. About two-thirds of the water in the aquifers is saline to brine, which complicates the modeling. Land subsidence due to water withdrawal also was modeled.

Professional Paper↗
USGS1998

Summary of hydrology of the regional aquifer systems, Gulf Coastal Plain, south-central United States

There is potential for further development of ground-water supplies in the Gulf Coastal Plain because of the abundance of water in streams, lakes, and swamps and the generally good hydraulic connection between the water table and underlying water-yielding units. The most favorable conditions for further development of ground-water supplies are generally in the upper permeable zones and aquifers, and the potential for development typically increases from west to east.

Alabama, Arkansas, Louisiana, Mississippi, Oklahom↗
USGS1990

Ground-water flow in the Gulf Coast aquifer systems, south central United States — A preliminary analysis

A major objective of the Gulf Coast Regional Aquifer-System Analysis is to use digital models of regional groundwater flow systems to develop better understanding and to improve management of the resource. Modeling is used to synthesize information about the aquifer systems and to test hypotheses about the relative importance of the components of the systems. The 290,000-sq mile study area in the Gulf of Mexico Coastal Plain includes the Mississippi embayment, Gulf Coastal Plain of Texas, and the Continental Shelf that are underlain by deposits of Tertiary and younger age, which contain fresh and saline water. A 10-layer, finite-difference, variable density model, with blocks 10 miles on a side, was used to simulate groundwater flow before development and in 1980, assuming steady- state conditions. Preliminary results indicate that the major factors controlling predevelopment regional flow are the topography, land-surface outcrop pattern, and geometry of aquifers and confining units. Geologic structure and the distribution of precipitation were less significant factors. The density of saline water in the deeper parts of the aquifer system probably has a substantial effect on regional groundwater flow that extends into the freshwater part of the system. Variable water density may be a significant driving force that transports salt great distances in many directions, including updip. The distribution and rates of regional recharge and discharge have been substantially changed by development. Groundwater pumpage in 1980 was about five times the value of predevelopment regional recharge. About 80% of the pumpage was supplied from increased regional recharge. Also resistance to vertical flow caused by many fine-grained beds within the permeable zones can be as important as resistance caused by regional confining units.

Gulf Coast aquifer systems↗
USGS1986

Gulf Coast Regional Aquifer-System Analysis — A Mississippi perspective

The Gulf Coast Regional Aquifer-System Analysis is a study of regional aquifers in sediments of mostly Cenozoic age in an area of about 230,000 sq mi in the Central Plain of Alabama, Arkansas , Florida, Illinois, Kentucky, Louisiana, Mississippi, Missouri, Tennessee, and Texas, and an additional 60,000 sq mi offshore. Three aquifer systems have been identified: the Mississippi embayment aquifer system, the Texas coastal uplands aquifer system, and the coastal lowlands aquifer system. These aquifer systems thicken from < 100 ft near their updip limit to thousands of ft gulfward toward their downdip limits. The Mississippi embayment aquifer system exceeds 5,000 ft in thickness in central Louisiana and in southwestern Mississippi. The thickest area in southwestern Mississippi underlies most of the six Mississippi counties, centered around Jefferson County. The greatest thickness of the coastal lowlands aquifer system in Mississippi occurs in southern Hancock County where the system is composed of several individual aquifers and confining units. There are seven aquifers and three confining units in the Mississippi embayment aquifer system, five aquifers and two confining units in the Texas coastal uplands aquifer system, and five aquifers and two confining units in the coastal lowlands aquifer system. Most of the thicker parts of each aquifer system contain moderately saline to very saline water. Water in the Mississippi embayment aquifer system is moderately saline to very saline in most of a seven county area in southwestern Mississippi. About 9,600 million gal/day (gpd) of ground water was pumped from the aquifers in the study area during 1980. About 15% of that pumpage (or about 1,400 million gpd was in Mississippi, mostly from the Mississippi River Valley alluvial aquifer of the Mississippi embayment aquifer system. About 10% of the Mississippi pumpage, or 140 million gpd, was from the coastal lowlands aquifer system. Preliminary results from simulation of groundwater flow indicates that parts of Mississippi are major regional recharge areas for both the Mississippi embayment aquifer system and the coastal lowlands aquifer system.

Mississippi↗
USGS1982

A Numerical model to evaluate proposed ground-water allocations in southwest Kansas

A computer model was developed to assist the Southwest Kansas Groundwater Management District No. 3 in the evaluation of applications to appropriate ground water. The model calculated the drawdown due from a proposed well at all existing wells in the section of the proposed well and at all wells in the adjacent eight sections. The depletion expected in the 9-square-mile area due to all existing wells and the proposed well is computed and compared with allowable limits defined by the management district. An optional program permits the evaluation of allowable depletion for one or more townships. All options are designed to run interactively, thus allowing for immediate evaluation of proposed ground-water withdrawals. (USGS)

Water-Resources Investigations Report↗
USGS1977

Potential for downward leakage to the Floridan Aquifer, Green Swamp area, central Florida

A qualitative evaluation of the potential for downward leakage from the surficial sand aquifer to the underlying Floridan aquifer was made for the Green Swamp area (about 870 sq mi) in central Florida. Downward leakage, or recharge, is limited under natural conditions owing to the nearness to land surface of the potentiometric surface of both the sand aquifer and the underlying Floridan aquifer. Continuous cores of the unconsolidated section were obtained at 74 sites in the study area and were evaluated for downward leakage potential based on grain-size distribution. Sand percentage was estimated for each interval or bed from microscopic examination of the core samples. The four maps prepared from this data show sand thickness, clay thickness, relative vertical hydraulic conductivity of the confining beds and the relative potential for downward leakage. About 20 percent (178 sq mi) of the area classified has a relatively good potential for downward leakage; almost 50 percent of the area has a relatively poor potential. (Woodard-USGS)

Florida↗