Geology Reports⌕ Search

SEARCH · Geology Reports

Results for “Hydrology”

Search indexed USGS publications on groundwater, aquifers, geologic maps, mineral resources and earthquakes. Explore source records by subject and place.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,765 records · Page 98Linked to original sources
USGS1988

Hydrologic analysis of the Rio Grande basin north of Embudo, New Mexico, Colorado and New Mexico

Water yield was estimated for each of the five regions that represent contrasting hydrologic regimes in the 10,400 square miles of the Rio Grande basin above Embudo, New Mexico. Water yield was estimated as 2,800 cubic feet per second for the San Juan Mountains, and 28 cubic feet per second for the Taos Plateau. Evapotranspiration exceeded precipitation by 150 cubic feet per second on the Costilla Plains and 2,400 cubic feet per second on the Alamosa Basin. A three-dimensional model was constructed to represent the aquifer system in the Alamosa Basin. A preliminary analysis concluded that: (1) a seven-layer model representing 3,200 feet of saturated thickness could accurately simulate the behavior of the flow equation; and (2) the 1950 condition was approximately stable and would be a satisfactory initial condition. Reasonable modifications to groundwater withdrawals simulated 1950-79 water-level declines close to measured value. Sensitivity tests indicated that evapotranspiration salvage was the major source, 69 to 82 percent, of groundwater withdrawals. Evapotranspiration salvage was projected to be the source of most withdrawals.

Colorado, New Mexico↗
USGS1986

Review of the hydrologic data-collection network in the St. Joseph River basin, Indiana

The St. Joseph River Basin data-collection network in the St. Joseph River for streamflow, lake, ground water, and climatic stations was reviewed. The network review included only the 1700 sq mi part of the basin in Indiana. The streamflow network includes 11 continuous-record gaging stations and one partial-record station. Based on areal distribution, lake effect , contributing drainage area, and flow-record ratio, six of these stations can be used to describe regional hydrology. Gaging stations on lakes are used to collect long-term lake-level data on which to base legal lake levels, and to monitor lake-level fluctuations after legal levels are established. More hydrogeologic data are needed for determining the degree to which grouhd water affects lake levels. The current groundwater network comprises 15 observation wells and has four purposes: (1) to determine the interaction between groundwater and lakes; (2) to measure changes in groundwater levels near irrigation wells; (3) to measure water levels in wells at special purpose sites; and (4) to measure long-term changes in water levels in areas not affected by pumping. Seven wells near three lakes have provided sufficient information for correlating water levels in wells and lakes but are not adequate to quantify the effect of groundwater on lake levels. Water levels in five observation wells located in the vicinity of intensive irrigation are not noticeably affected by seasonal withdrawals. The National Weather Sevice operates eight climatic stations in the basin primarily to characterize regional climatic conditions and to aid in flood forecasting. The network meets network-density guidelines established by the World Meterological Organization for collection of precipitation and evaporation data but not guidelines suggested by the National Weather Service for density of precipitation gages in areas of significant convective rainfalls. (Author 's abstract)

Indiana↗
USGS1986

A description of the hydrologic system and the effects of coal mining on water quality in the East Fork Little Chariton River and the alluvial aquifer between Macon and Huntsville, north-central Missouri

The quality of surface and groundwater has been affected by abandoned strip mines and by abandoned underground mines in a 110-sq mi subbasin of the East Fork Little Chariton River. More than 14% of the area was strip mined for coal before 1979. The hydrologic system in the area was investigated and the effects of coal mining on quality of water in the river and alluvial aquifer were analyzed, with major emphasis on defining strip-mining effects. The groundwater gradient was from glacial drift or coal spring to alluvium to the East Fork Little Chariton River, and was greatest in spring and least in fall. Seepage from alluvium to the East Fork Little Chariton River occurs throughout the year, except during drought conditions when the only river flow is water released from Long Branch Lake. In the East Fork Little Chariton River median dissolved-solids concentrations increased from 153 mg/L near Macon to 630 mg/L near Huntsville and median sulfate concentrations increased from 36 mg/L near Macon to 360 mg/L near Huntsville. The median dissolved-solids concentration in water from the alluvium increased from 408 mg/L upstream from the strip mines to 641 mg/L near the mines and median dissolved-sulfate concentration increased from 140 to 350 mg/L. The sulfate-to-chloride ratio, used as the most sensitive indicator of strip-mining effects, increased markedly downstream in the East Fork Little Chariton River and nearby Middle Fork Little Chariton River, which also is affected by strip mining. There were no significant increases in sulfate-to-chloride ratio and dissolved-solids concentrations in comparable nearby subbasins of the Grand, Thompson, and Chariton Rivers where there was no mining. (Author 's abstract)

Water-Resources Investigations Report↗
USGS1986

Geohydrology and potential hydrologic effects of underground coal mining in the Rapid Creek Basin, Mesa County, Colorado

The U.S. Bureau of Land Management may lease additional coal tracts in the Rapid Creek basin, Colorado. Springs in this basin are used as a water supply for the town of Palisade. The geohydrology of the basin is described and the potential hydrologic effects of underground coal mining in the basin summarized. Geologic formations in the basin consists of Cretaceous sandstone and shale, Tertiary sandstone, shale, and basalt, and unconsolidated deposits of Quaternary age. Some sandstone and coal beds are permeable, although bedrock in the basin typically is a confining bed. Unconsolidated deposits contain aquifers that are the source of spring discharge. Stream discharge was measured on Rapid and Cottonwood Creeks, and inventories were made of 7 reservoirs, 25 springs, and 12 wells. Specific conductance of streams ranged from 320 to 1,050 microsiemens/cm at 25C; pH ranged from 7.8 to 8.6. Specific conductance of springs ranged from 95 to 1,050 microsiemens/cm at 25C; pH ranged from 6.8 to 8.3. Discharge from the basin includes about 18,800 acre-ft/yr as evapotranspiration, 1,300 acre-ft/yr as springflow, 1,280 acre-ft/yr as streamflow, and negligible groundwater flow in bedrock. With appropriate mining methods, underground mining would not decrease flow in basin streams or from springs. The potential effects of mining-caused subsidence might include water-pipeline damage and temporary dewatering of bedrock adjacent to coal mining. (Author 's abstract)

Water-Resources Investigations Report↗
USGS1986

Investigation of possible effects of surface coal mining on hydrology and landscape stability in part of the Powder River structural basin, northeastern Wyoming

The effects of surface coal mining on the surface- and groundwater systems in a 5,400 sq mi area in the Powder River Basin, Wyoming, that includes 20 major coal mines were evaluated using three approaches: A surface water model, a landscape-stability analysis, and a groundwater model. A surface water model was developed for the Belle Fourche River basin. The Hydrological Simulation Program-Fortran model was used to simulate changes in streamflow and changes in dissolved-solids and sulfate concentrations. Simulated streamflows resulting from less than average rainfall were small, changes in flow from premining to during-mining and postmining conditions were less than 2.5%, and changes in mean dissolved-solids and sulfate concentrations ranged from 1 to 7%. A landscape-stability analysis resulted in regression relations to aid in the reconstruction of reclaimed drainage networks. Hypsometric analyses indicate the larger basins are relatively stable, and statistical data from these basins may be used to design the placement of material within a mined basin to approximate natural, stable landscapes in the area. The attempt to define and simulate the groundwater system in the area using a groundwater-flow model was unsuccessful. The steady-state groundwater-flow model could not be calibrated. The modeling effort failed principally because of insufficient quantity and quality of data to define the spatial distribution of aquifer properties; the hydraulic-head distribution within and between aquifers; and the rates of groundwater recharge and discharge, especially for steady-state conditions. (USGS)

Water-Resources Investigations Report↗
USGS1987

Surface-water hydrology of the Little Black River basin, Missouri and Arkansas, before water-land improvement practices

The U. S. Department of Agriculture, Soil Conservation Service, in accordance with Public Law 566, is implementing various types of water-land improvement practices in the Little Black River basin in southeastern Missouri. These practices are designed, in part, to decrease the suspended sediment (SS) transport in the basin, decrease flood damage in the basin, and improve drainage in the agricultural area. The general features of the basin, such as geology, groundwater hydrology, soils, land use, water use, and precipitation are described; surface water quantity, quality, and suspended sediment discharge are also described. The aquifers are the Mississippi River valley alluvial aquifer, which can yield about 3,500 gal/min to properly constructed wells, and the Ozark and St. Francois aquifers, which can yield from about 30 to 500 gal/min to properly constructed wells. Soils in the area have formed in loess and cherty residuum in the uplands or have formed in alluvial sediment in the lowlands. About 93% of the estimated 3 billion gal/year of water used in the basin is for crop irrigation. The average monthly precipitation varies slightly throughout the year, with an average annual precipitation of about 47 inches. Water quality data were collected at seven stations. Specific conductance values ranged from 50 to 400 microsiemens/cm at 25 C. Water temperatures ranged from 0.0 C in the winter to 33.5 C in summer. pH values ranged from 6.4 to 8.5 units. Dissolved oxygen concentrations ranged from 2.2 to 12.8 ml/l. Total nitrogen concentrations ranged from 0.13 to 2.20 ml/l as nitrogen, with organic nitrogen as the most abundant form. Phosphorus concentrations ranged from zero to 0.29 ml/l as phosphorus. Bacterial counts were largest during storm runoff in the basin with livestock waste as the significant contributor. For the period from October 1, 1980, to September 30, 1984, the average annual SS discharge ranged from 2,230 tons/yr in the headwater areas to 27,800 tons/yr at the most downstream station. The average annual SS yield ranged from 59.6 to 85.9 tons/sq mi.

Arkansas, Missouri↗
USGS1988

Hydrologic effects of phreatophyte control, Acme-Artesia reach of the Pecos River, New Mexico, 1967-82

The U.S. Bureau of Reclamation began a phreatophyte clearing and control program in the bottom land of the Acme-Artesia reach of the Pecos River in March 1967. The initial cutting of 19,000 acres of saltcedar trees, the dominant phreatophyte in the area, was completed in May 1969. Saltcedar regrowth continued each year until July 1975, when root plowing eradicated most of the regrowth. The major objective of the clearing and control program was to salvage water that could be put to beneficial use. Measurements of changes in the water table in the bottom land and changes in the base flow of the Pecos River were made in order to determine the hydrologic effects of the program. Some salvage of water was indicated, but it is not readily recognized as an increase in base flow. The quantity of salvage probably is less than the average annual base-flow gain of 19 ,110 acre-ft in the reach during 1967-82. (Author 's abstract)

Water-Resources Investigations Report↗
USGS1988

Hydrology of the lower Little Red River, Arkansas, and a procedure for estimating available streamflow

The U.S. Geological Survey, in cooperation with the Arkansas Soil and Water Conservation Commission, conducted a hydrologic investigation of the lower Little Red River from near Searcy, Arkansas (mi 31.7), to the river 's mouth at its confluence with the White River. During 1983 and 1984, data were collected on streamflow, stream altitude, groundwater altitude and diversion pumping from the Little Red River. Flow in the Little Red River near Searcy is computed by using a modified stage/fall/discharge relation and stage data collected at Searcy and at Judsonia 6.5 mi downstream. This procedure uses a family of 12 rating curves that can be selected by stage records at Searcy and fall records between Searcy and Judsonia. A comparison of water levels in the river to water levels in selected alluvial wells near the river indicates that the Little Red is a gaining stream during summer and fall low periods and is a losing stream during periods of high flow. Flows in the lower Little Red River are also significantly affected by releases from Greers Ferry Reservoir at mi 78.8 and by varying backwater conditions resulting from high stages on the White River. To meet the expressed needs of the Arkansas Soil and Water Conservation Commission, a mass balance procedure was developed to be used for estimating the amount of streamflow available along a reach of stream, given a minimum instream flow requirement set by the regulating authority. This procedure was coded into a computer program that can be invoked interactively as an aid in making streamflow allocation decisions and in maintaining related data bases. (USGS)

Water-Resources Investigations Report↗
USGS1989

Geohydrology of the Escondido hydrologic subarea, San Diego County, California

The San Diego region of California is undergoing rapid growth with a corresponding increase in the demand for water. To update the basin plan developed in 1975 by the California Regional Water Quality Control Board, San Diego Region, water-level and water quality data for the 44-sq mi Escondido hydrologic subarea were collected and analyzed. Water-level measurements indicate that groundwater in most of the subarea was within 20 ft of land surface. Groundwater generally moves from the weathered crystalline rocks on hillsides into the alluvium. Groundwater moves from north to south in Reidy Canyon and from east to west in the alluvium along Escondido Creek. Water from all 20 wells sampled in 1987 had dissolved-solids concentrations greater than the U.S. Environmental Protection Agency recommended limit of 500 mg/L; concentrations ranged from 720 to 4,500 mg/L. Nitrate (as nitrogen) concentrations ranged from 1.1 to 86 mg/L. Water from 14 of the 20 wells had nitrate (as nitrogen) concentrations greater than the U.S. Environmental Agency recommended limit of 10 mg/L. (USGS)

Water-Resources Investigations Report↗
USGS1990

Hydrology, aquatic macrophytes, and water quality of Black Earth Creek and its tributaries, Dane County, Wisconsin, 1985-86

An intensive data-collection program for the Black Earth Creek basin in southern Wisconsin was conducted from October 1984 through September 1986 to assess the hydrology, aquatic macrophytes, and water quality in Black Earth Creek by the U.S. Geological Survey, in cooperation with the Wisconsin Department of Natural Resources. Three sites on two cold-water trout streams Black Earth Creek at Cross Plains, Black Earth Creek near Cross Plains, and Garfoot Creek near Cross Plains were continuously monitored for streamflow and water-quality data. One site in a warm-water stream, Brewery Creek at Cross Plains, also was monitored. Aquatic macrophyte biomass was determined for three sites on Black Earth Creek. Streamflow at Black Earth Creek at Black Earth during the 1985 and 1986 water years (WY) were 44 and 60 percent greater than the long-term mean discharge of 33.3 ft3/s (cubic feet per second) for the period 1955-86. Water year 1986 had the highest annual mean discharge, 53.4 ft3/s, since records began in 1954 at the most downstream site Black Earth Creek at Black Earth. Although there have been considerable fluctuations in streamflow, it has tended to increase since WY 1965 as a result of above-average precipitation and consequent rising ground-water levels. Trout population densities may be related to annual mean streamflow. A regression analysis of adult trout populations and the 3-year moving annual mean discharge had a correlation coefficient of 0.75 with a standard error of 83 percent. Aquatic macrophyte biomass in Black Earth Creek was substantially less in 1986 than in 1985 as a result of substrate scouring from the flood of July 25, 1985. The frequency of occurrence of species during 1985 and 1986 was similar to that of 1981, and seasonal succession of species also was similar; Potamogeton crispus dominated early in the year and senesced in July. P. crispus and P. pectinatus, both indicative of eutrophic conditions, dominated upstream and downstream, respectively; neither species is native to the area. In 1985, the greatest biomass was found upstream from Cross Plains. This large biomass caused diurnal fluctuations in dissolved-oxygen concentration of 5 to 6 mg/L (milligrams per liter) as a result of photosynthesis and respiration. Many of the dissolved-oxygen minimums, recorded at night, were less than the State 6.0-mg/L water-quality standard for trout waters. Discharge from point sources may adversely affect Black Earth Creek's water quality. Warm water discharged to Black Earth Creek from a gravel pit operation upstream from Cross Plains increased water temperatures 2 to 4 degrees Celsius and decreased the dissolved oxygen about 1 mg/L at a site 1.8 miles downstream. Runoff from a settling pond from a landfill operation in the headwaters of the Black Earth Creek basin drains through a wetland that drains to Black Earth Creek and contained as much as 60 mg/L ammonia nitrogen, 980 mg/L biochemical oxygen demand, and 1,300 mg/L chemical oxygen demand, which may be detrimental to trout. Garfoot Creek had the highest suspended-sediment and phosphorus yields per unit area of the three upstream basins during low to moderate runoff. Detention ponds in the Brewery Creek basin appear to be less effective in controlling suspended-sediment and phosphorus loads during periods of high runoff than during moderate runoff. Brewery Creek had the highest concentrations of suspended sediment and total phosphorus during low and high flows. The water quality at the Black Earth Creek gaging station at Black Earth was affected by Garfoot Creek and unnamed tributaries. As a result, yields of suspended sediment, phosphorus, and nitrogen increased between Cross Plains and Black Earth. High streamflows during WY 1985 resulted in suspendedsediment yields at Black Earth Creek at Black Earth that were 29 percent greater than the 12-year (1955-65, 85-86) mean; yields ranged from 69.5 ton/mi2 (tons per square mile) in Black Earth Creek at Cross Plains to 116 ton/mi2 in the Brewery Creek basin. Phosphorus yields ranged from 312 lb/mi2 (pounds per square mile) in Black Earth Creek at Cross Plains to 628 lb/mi2 in the Brewery Creek basin. Total nitrogen yields ranged from 3,280 lb/mi2 in the Brewery Creek basin to 6,920 lb/mi2 in the Garfoot Creek basin. An increase in oxygen demand, caused by agricultural runoff, has resulted in reduced dissolved-oxygen content of the water in both Black Earth and Garfoot Creeks. The most substantial reduction occurred at Black Earth Creek at Cross Plains on July 25, 1985, as a result of the largest storm runoff event during the study. A rainfall of 5.54 inches caused streamflow discharges to increase from 9 to 122 ft3/s and dissolved-oxygen concentrations to decline to 3.0 mg/L; the dissolved-oxygen concentration was less than 6.0 mg/L for 30 hours.

Wisconsin↗
USGS1991

Hydrology of Lakes Clara and Vandercook in north-central Wisconsin

Lakes Clara and Vandercook are 33- and 43-hectare lakes, respectively, located in predominantly sandy outwash in north-central Wisconsin. Annual precipitation at National Weather Service stations during the 1951-80 calendar years averaged 794 millimeters near Lake Clara and 834 millimeters near Vandercook Lake. During the 1981 water year, annual precipitation measured at the lakes as part of this study was 3 percent below average for Lake Clara and 16 percent below average for Vandercook Lake. Annual precipitation was 6 to 21 percent above average for the two lakes during the 1982 and 1983 water years. Lake stage and water-table altitudes were relatively constant at Lake Clara throughout the 3 water years of study and at Vandercook Lake during the 1981 and 1982 water years; however, Vandercook Lake stage increased 0.2 meter, and the upgradient water table increased 0.3 meter, during the 1983 water year. Hydrologic budgets show that lake inflow was dominated by precipitation (77 to 91 percent for Lake Clara and 79 to 87 percent for Vandercook Lake). Ground water accounted for the remaining inflow to Vandercook Lake; however, Lake Clara received approximately equal contributions from ground-water inflow and overland flow. Evaporation was the major form of lake outflow (59 to 75 percent for Lake Clara and 59 to 63 percent for Vandercook Lake). The remaining outflow from Vandercook Lake was to the ground-water system, but Lake Clara lost approximately equal amounts by surface and ground-water outflow. Hydraulic residence times were 4 to 5 years for both lakes. Chemical residence times for conservative constituents were 11 to 21 years for Lake Clara and 10 to 13 years for Vandercook Lake.

Wisconsin↗
USGS1990

Effects of channel modifications on the hydrology of Chicod Creek basin, North Carolina, 1975-87

Drainage modifications in this Coastal Plain basin from 1978 to 1981 consisted of channel excavation and clearing of blockages. A study was begun in 1975 to define hydrologic conditions of the basin before, during, and after modifications and to determine what changes were attributed to modifications. Surface-water conditions were altered during and following modifications. Minimum flow at Juniper Branch was increased from less than 0.1 cu ft/sec to 0.4 cu ft/second;streamflow variability was reduced from an index of 0.87 to 0.49. In-channel velocity at Chicod Creek was increased from a mean of 0.4 ft/sec to 1.5 ft/sec. Substantial groundwater level declines were observed in wells 180 and 250 ft from Juniper Branch during the modifications phase;these were 0.4 and 0.2 ft, respectively. However, most surface-water and groundwater conditions returned nearly to premodification levels by 1987. Water-quality characteristics monitored during the investigation included physical, chemical, and bacteriological characteristics. Physical characteristics monitored were suspended sediment, temperature, dissolved oxygen, and pH. Of these physical characteristics, only sediment concentrations increased substantially during channel modifications. Chemical characteristics studied were major dissolved constituents, nutrients, trace metals, and pesticides. Substantial changes ranged from a decline in total iron concentrations of 77% to an increase in total nitrite concentrations of 130%. Changes in many chemical characteristics persisted following channel modifications. Bacterial counts did not change substantially.

North Carolina↗
USGS1990

Hydrology and land use in Grand Traverse County, Michigan

Glacial deposits are the sole source of ground-water supplies in Grand Traverse County. These deposits range in thickness from 100 to 900 feet and consist of till, outwash, and materials of lacustrine and eolian origin. In some areas, the deposits fill buried valleys that are 500 feet deep. Sedimentary rocks of Paleozoic age, which underlie the glacial deposits, are mostly shale and are not used for water supply. Of the glacial deposits, outwash and lacustrine sand are the most productive aquifers. Most domestic wells obtain water from sand and gravel at depths ranging from 50 to 150 feet and yield at least 20 gallons per minute. Irrigation, municipal, and industrial wells capable of yielding 250 gallons per minute or more are generally greater than 150 feet deep. At places in the county where moranial deposits contain large amounts of interbedded silt and clay, wells are generally deeper and yields are much lower. Areal variations in the chemical and physical characteristics of ground and surface water are related to land use and chemical inputs to the hydrologic system. Information on fertilizer application, septic-tank discharges, animal wastes, and precipitation indicate that 40 percent of nitrogen input is from precipitation, 6 percent from septic tanks, 14 percent from animal wastes, and 40 percent from fertilizers. Streams and lakes generally have a calcium bicarbonate-type water. The dissolved-solids concentration of streams ranged from 116 to 380 milligrams per liter, and that of lakes, from 47 to 170 milligrams per liter. Water of streams is hard to very hard; water of lakes ranges from soft to hard. The maximum total nitrogen concentration found in streams was 4.4 milligrams per liter. Water of lakes have low nitrogen concentrations; the median nitrate concentration is less than 0.01 milligrams per liter. Pesticides (Parathion and Simazine) were detected in low concentrations at six stream sites; 2,4-D was detected in low concentrations in water of two lakes. Relationships between land use and the yield of dissolved and suspended substances could not be established for most stream basins. Calcium and bicarbonate are the principal dissolved substances in ground water. Dissolved-solids concentrations ranged from 70 to 700 milligrams per liter; the countywide mean concentration is 230 milligrams per liter. The mean nitrate concentration is 1.3 milligrams per liter; about 1.6 percent of the county's ground water has nitrate concentrations that exceed the U.S. Environmental Protection Agency's maximum drinking water level of 10 milligrams per liter. An effect of fertilizer applications on ground-water quality is evident in some parts of the county.

Michigan↗
USGS1993

Hydrology, water quality, trophic status, and aquatic plants of Fowler Lake, Wisconsin

The U.S. Geological Survey, in cooperation with the Fowler Lake Management District, completed a hydrologic and water-quality study of Fowler Lake in southeastern Wisconsin during calendar year 1984. Data on temperature, pH, specific conductance, and concentrations of dissolved oxygen, total phosphorus, dissolved orthophosphate phosphorus, and various nitrogen species were collected from January through November 1984. The water-quality data indicate that Fowler Lake can be classified as a mildly fertile lake with excellent water clarity as indicated by Secchi depth readings generally greater than 12 feet. Although phosphorus concentrations are generally less than 0.01 milligram per liter, the lake does produce dense stands of macrophytes during the open-water period. The lake is thermally stratified during the summer months, resulting in oxygen depletion in the deepest parts of the lake. The average hydraulic residence time for Fowler Lake during 1984 was 6.9 days, which is substantially less than the 305 days for upstream Okauchee Lake or the 145 days for downstream Lac La Belle. Precipitation during 1984 was about 27 percent higher than normal and streamflows in the area were about 55 percent higher than normal. The Oconomowoc River contributed 98 percent of the inflow and 88 percent of the phosphorus load to Fowler Lake. The low annual phosphorus input (28 pounds per square mile) to the lake from the Oconomowoc River shows the benefit of upstream lakes on the Oconomowoc River. Fourteen percent of the phosphorus input load to Fowler Lake is deposited in the lake sediments and the rest is transported through the lake by surface-water flow to downstream Lac La Belle. Dense growths of macrophytes in the lake change in composition seasonally; chara sp. (muskgrass) and Myriophyllum sp. (milfoil) are abundant in June and Najas marina and Vallesneria Americana (wild celery) are abundant in August.

Wisconsin↗
USGS1994

Hydrology, water quality, and potential alternatives for water-resources development in the Río Majada and Río Lapa basins near the Albergue Olimpico, southern Puerto Rico

A water-resources investigation was conducted during 1989 in the Rio Lapa mountain basins in southern Puerto Rico, to define the hydrology, water quality, and to describe alternatives for additional water- resources supply. The total water budget for both surface- and ground-water resources in the study area was estimated to be 7,530 acre-feet per year for 1989. The water budget for the ground-water system, from which water needs are supplied in the study area, was estimated to be 2,760 acre-feet per year for 1989. Concentration of dissolved solids and fecal bacteria increased during the dry season as both streamflow and ground-water levels decreased. Water samples collected at two stream sites exceeded the recommended U.S. Environmental Protection Agency fecal bacteria concentration for natural water of 2,000 colonies per 100 milliliters during June to November 1989. Water samples obtained from a well in the Rio Lapa Valley exceeded the secondary drinking-water standard for dissolved solids of 500 milligrams per liter during four dry months. In addition, fecal bacteria concentrations at this water-supply well exceeded the primary fecal- bacteria drinking-water standard of 1 colony per 100 milliliter during June to October 1989. Existing water resources can probably be developed to meet additional demands of 110 acre-feet per year pro- jected for 1995. Storage of the surface-water runoff during the wet season and its gradual release to the study area could offset ground-water declines during the dry season. Ground-water withdrawals can be increased by the construction and use of low- capacity wells to reduce the amount of water lowing out of the study area.

Puerto Rico↗
USGS1992

Hydrology of the Cave Springs area near Chattanooga, Hamilton County, Tennessee

The hydrology of Cave Springs, the second largest spring in East Tennessee was investigated from July 1987 to September 1989. Wells near the spring supply about 5 million gallons per day of potable water to people in Hamilton County near Chattanooga. Discharge from the spring averaged about 13.5 cubic feet per second (8.72 million gallons per day) during the study period. Withdrawals by the Hixson Utility District from wells upgradient from the outflow averaged 8.6 cubic feet per second (5.54 million gallons per day). Aquifer tests using wells intersecting a large solution cavity supplying water to the spring showed a drawdown of less than 3 feet with a discharge of 9,000 gallons per minute or 20 cubic feet per second. Temperature and specific conductance of ground water near the spring outflow were monitored hourly. Temperatures ranged from 13.5 to 18.2 degrees celsius, and fluctuated seasonally in response to climate. Specific-conductance values ranged from 122 to 405 microsiemens per centimeter at 25 degrees Celsius, but were generally between 163 to 185 microsiemens per centimeter. The drainage area of the basin recharging the spring system was estimated to be 1O square miles. A potentiometric map of the recharge basin was developed from water levels measured at domestic and test wells in August 1989. Aquifer tests at five test wells in the study area indicated that specific-capacity values for these wells ranged from 4.1 to 261 gallons per minute per foot of drawdown. Water-quality characteristics of ground water in the area were used in conjunction with potentiometric-surface maps to delineate the approximate area contributing recharge to Cave Springs.

Tennessee↗
USGS1992

Documentation of a digital spatial data base for hydrologic investigations, Broward County, Florida

Geographic information systems have become an important tool in planning for the protection and development of natural resources, including ground water and surface water. A digital spatial data base consisting of 18 data layers that can be accessed by a geographic information system was developed for Broward County, Florida. Five computer programs, including one that can be used to create documentation files for each data layer and four that can be used to create data layers from data files not already in geographic information system format, were also developed. Four types of data layers have been developed. Data layers for manmade features include major roads, municipal boundaries, the public land-survey section grid, land use, and underground storage tank facilities. The data layer for topographic features consists of surveyed point land-surface elevations. Data layers for hydrologic features include surface-water and rainfall data-collection stations, surface-water bodies, water-control district boundaries, and water-management basins. Data layers for hydrogeologic features include soil associations, transmissivity polygons, hydrogeologic unit depths, and a finite-difference model grid for south-central Broward County. Each data layer is documented as to the extent of the features, number of features, scale, data sources, and a description of the attribute tables where applicable.

Florida↗
USGS1993

Geomorphic, hydrologic, and erosion data for selected reclaimed hillslopes, the Seneca II mine, Routt County, Colorado, October 1988-July 1990

Geomorphic, hydrologic, and erosion data were collected from five reclaimed hillslopes at the Seneca II mine near Hayden, Colorado. Hillslope surveys were used to determine hillslope lengths, which range from 670 to 1,280 ft, and hillslope gradients, which range from 0.17 to 0.23 ft/ft (17 to 23 percent). Elevations in the study area range from 6,890 to 7,140 feet and hillslope aspect generally is west or south. Mean total vegetation cover ranges from 74 to 91 percent. Total monthly precipitation for December 1988 through May 1990 was computed from daily measurements made with weighing-bucket precipitation gages. Several snowpack measurements were made during 2 winters. Volumetric soil-water content was determined at incremental depths using a neutron probe and in the upper 11.8 in of soil using a time-domain reflectometer. Active and recent soil erosion was indicated by the presence of rills. Rill density (the sum of rill lengths/unit area) was computed at 50-feet intervals along each hillslope study area. Differences in soil-surface elevations between September or October 1989 and June 1990 were determined with an erosion frame and replicate soil-surface surveys at 16 erosion-study plots.

Colorado↗