U.S. Geological Survey
U.S. Geological Survey
The USGS provides maps, reports, and information to help others meet their needs to manage, develop, and protect America's water, energy, mineral, and land resources. We help find natural resources needed to build tomorrow, and supply scientific understanding needed to help minimize or mitigate the effects of natural hazards and environmental damage caused by human activities. The results of our efforts touch the daily lives of almost every American.
A cooperative project between the USGS and Alabama was initiated in 1978 to collect, evaluate, and correlate drill-hole, mine, and outcrop data; to encode and enter geologic and geochemical data into the NCRDS; and to access NCRDS data bases and software to generate new maps, reports, and resource assessments. The continued data collection and support of the NCRDS data bases provide baseline information that can be accessed for annual State resource updates and used to meet many foreseen and even unforeseen needs as they arise.
Effects of Federal Rulemaking on Coal Markets
The Office of Surface Mining (OSM) is establishing a Federal rule for Valid Existing Rights that could affect access to coal in environmentally sensitive areas and is determining whether underground mining should be prohibited in environmentally sensitive areas. To complete a valid rule-making action, the OSM is preparing an environmental impact statement in accordance with the National Environmental Policy Act and an economic analysis in accordance with Executive Order No. 12866. The USGS is providing coal-resource assessment and economic analysis to the OSM to support the preparation of the environmental impact statement and economic analysis. The USGS performs the following assessments:
Figure 1. Water use in Alabama, by county, for 1990.
Competition for water has increased as increased use of water has reduced flow in rivers and lowered ground-water levels in some areas of the State and caused saltwater intrusion into aquifers in coastal areas. To resolve these conflicts, State and Federal agencies are evaluating water resources in some areas. The USGS provides needed information on water quality and quantity and water use so that planners and other officials can make informed decisions on water-resources issues.
The Alabama-Coosa-Tallapoosa River Basin
The Alabama-Coosa-Tallapoosa River Basin is an area where competing demands for water have caused concern among planners and developers. The headwaters of the Basin are in northern Georgia where expanding urban areas are placing increased demands on the water resources that, in turn, reduce available water resources downstream in Alabama. Between 1970 and 1990, water used for public supply in the portion of the Alabama-Coosa-Tallapoosa Basin in Alabama increased 44 percent to almost 185 million gallons per day. During that period, withdrawals for self-supplied commercial/industrial users decreased by about 5 percent. Explanations for this decrease are increased supplies by public-water-supply systems and more efficient use of water by industries. Total water use in the Alabama portion of the Alabama-Coosa-Tallapoosa Basin increased about 7 percent. The USGS, in cooperation with the Alabama Department of Economic and Community Affairs and the U.S. Army Corps of Engineers, is working on a series of reports to describe the ground-water resources for the Basin. The reports provide a scientific data base to be used for water-resource-management decisions that concern allocation of water resources within the Basin. The primary focus of the reports is assessment of low-flow conditions to develop a conceptual model of the ground-water-flow system, to estimate the volume of water entering and exiting subareas within the basin, to describe ground-water availability, and to identify areas where ground-water resources are overutilized or underutilized.
Baldwin County Area
Baldwin County is one of the fastest growing areas in Alabama. Presently, it is totally dependent on ground water for public-water supply and most agricultural, commercial, and industrial supply. In 1990, total ground-water withdrawals in the County were more than 30 million gallons per day.
Potential problems facing the area include saltwater intrusion near the coast, water shortages caused by overpumping, vulnerability of a single-source water supply to contamination, and competition among managers and planners. The USGS is answering questions about the amount of ground water that is available for use, recharge rates compared with withdrawal rates, the potential for saltwater intrusion, and what risks contaminants pose to water supplies.
Hydrologic Hazards
Floods and droughts are very damaging natural hazards in Alabama. In July 1994, rainfall from Tropical Storm Alberto caused flooding in several areas. In Alabama, damage was most serious along the Choctawhatchee and the Pea Rivers. This was one of the most damaging floods in history along these streams. Torrential rains from Alberto also produced extensive flash flooding in southeastern Alabama; many highways, bridges, and storm drainage systems were damaged. In all, 10 counties in Alabama had some type of flood damage. Damage from such a severe flood cannot be averted completely, but with sound hydrologic information, reliable estimates of peak river stages and discharge can be made, and communities can be warned of impending danger. Data collected during and after the flood by the USGS can help local, State, and Federal agencies to develop mitigation strategies in response to similar emergencies in the future.
With accurate estimates of flood magnitude and frequency, planners and managers can better design highway bridges and culverts, determine locations for water- and wastewater-treatment facilities, prepare zoning ordinances, and establish flood-insurance rates. Methods of estimating peak discharges for recurrence intervals of 2, 5, 10, 25, 50, 100, 200, and 500 years have been developed for rural streams in Alabama not affected by regulation or urbanization. Flood-frequency characteristics are defined for 200 streamflow gaging stations having 10 or more years of record through September 1991.
Each year, the USGS annually publishes streamflow and stage data and prepares reports that describe hydrologically significant floods. All data collected are stored in a computer data base and are available to the public.
The network of USGS surface-water data-collection stations also is used to document drought conditions and to prepare reports on low flows during droughts. In Alabama, the decade of the 1980's generally was characterized by below-normal-flow conditions, and the State experienced at least three significant periods of low-flow conditions 1981, 1986, and 1988. The USGS respon-ded to the drought conditions by making several nonroutine measurements of low-flow conditions. These data were published in the annual water data report.
Collection of Hydrologic Data
Alabama has 10 major rivers-the Tennessee, the Mobile, the Tombigbee, the Black Warrior, the Alabama, the Cahaba, the Coosa, the Tallapoosa, the Conecuh, and the Chattahoochee. The USGS, in cooperation with numerous local, State, and Federal agencies, has collected streamflow, ground-water, and water-quality data at sites throughout the State (fig.Ê2). Recent water-quality studies involve monitoring programs on water-supply reservoirs for Tuscaloosa, Birmingham, and Mobile, Alabama, a monitoring program on Locust Fork and some of its tributaries, and a countywide stream-monitoring program in Baldwin County. The data are needed for surveillance, planning, design, hazard warning, operation, and management in water-related fields such as water supply, hydroelectric-power generation, flood control, irrigation, bridge and culvert design, wildlife management, pollution abatement, flood-plain management, and water-resources development.
Figure 2. Water-quality data-collection sites in Alabama.
Potential Contamination
Where soil or ground water has been contaminated by human activities, the potential exists for contaminants to spread to other areas that could affect water supplies or cause direct health hazards for people living in those areas. The USGS, in cooperation with the U.S. Department of Defense, is conducting studies at selected military bases in Alabama where underground storage tanks and waste-disposal sites are potential sources of contaminants that could infiltrate to the ground water. The USGS is determining whether contaminants have been released and in which direction they are moving away from the site.
Evolution and History of Incised Valleys-Benefits to Shoreline Erosion Mitigation
Incised valleys along the Gulf Coast commonly result from rivers eroding the stream channel and valley wall materials rapidly in response to an increase in the velocity of streamflow caused by a fall in sea level. As sea level rises, sediments fill incised valleys and form near-shore elongated sand bodies, such as barrier islands (fig. 3). These sand bodies can be potential sites for hard-mineral accumulations and are modern analogues to buried sands in the ancient rock record with high potential for being oil and gas reservoirs. Processes that formed residual sediment accumulations also may help the State of Alabama predict the outcome of erosion mitigation strategies and wetland-nourishment efforts. Today, the geologic imprint of incised valleys across the continental shelf provides evidence of sea-level change over the past 18,000 years.
Figure 3. A schematic cross section showing shoal formation, developed by using seismic and core data collected from a submerged portion of the St. Bernard Delta (a lobe of the Mississippi River Delta). As sea level (SL 1 and 2) rose during the transgression, a barrier island arc was formed. In response to rising sea level, the barrier island migrated shoreward over lagoonal muds. Rising sea level (SL 3) drowned the barrier island and continuing sea level rise (SL 4) reworked the drowned barrier to form the St. Bernard Shoals.
National Mapping Program
Among the most popular and versatile products of the USGS are its 1:24,000-scale topographic maps (1 inch on the map represents 2,000 feet on the ground). These maps depict basic natural and cultural features of the landscape, such as lakes and streams, highways and railroads, boundaries, and geographic names. Contour lines are used to depict the elevation and shape of terrain. Alabama is covered by 912 maps at this scale, which is useful for civil engineering, land-use planning, natural-resource monitoring, and other technical applications. These maps have long been favorites with the general public for outdoor uses, including hiking, camping, exploring, and back-country fishing expeditions.
Earth Observation Data
Through its Earth Resource Observation Systems Data Center near Sioux Falls, South Dakota, the USGS distributes a variety of aerial photographs and satellite image data products that cover the entire State. Mapping photographs of some sites go back about 40 years. Satellite images dating from 1972 can be used to study changes in regional landscapes.
Landslide Hazards in Alabama
Although prehistoric landslides in Alabama include rock masses more than one-half of a mile across and fast-moving debris flows more than one-quarter of a mile long, most recent landslides appear limited to movements of less than about 100 yards across. These landslides, as well as smaller and faster slides and rockfalls, occur mostly where slopes have been steepened during construction of roads, but some homes on steep terrains have also been endangered. To better understand potential problems posed by landsliding in the State, the USGS has assisted the Geological Survey of Alabama in compiling an inventory of landslides, by using such sources as the Alabama Highway Department, county highway departments, the U.S. Forest Service, and scientific literature. Analysis of the compiled data shows that landsliding is most abundant in the northern part of the State, where it tends to be concentrated in particular mapped geologic units. This information helps in anticipating the distribution and cost effects of landsliding, and thereby helps developers, businesses, highway departments, and local agencies to improve the cost-effectiveness of engineered structures.
Cooperative Programs
Much of the USGS work in Alabama is pursued in partnership with many State and local agencies. Cooperative programs in 1994 included the following agencies: the Alabama Department of Environmental Management; the cities of Birmingham, Huntsville, Anniston, Greenville, Mobile, Tuscaloosa, and
Prattville; Coffee, Sumter, Jefferson, and Baldwin Counties; the Alabama Department of Economic and Community Affairs; the Alabama Emergency Management; the towns of Blountsville and Parrish; the Geological Survey of Alabama; the Alabama Department of Transportation; and Auburn University.
from U.S. Department of the Interior, U.S. Geological Survey, Fact Sheet FS-002-95