Geology topics

J.M. Fenelon

Publications and source records attributed to J.M. Fenelon.

4 recordsLinked to original sources

USGS2013

Detecting drawdowns masked by environmental stresses with water-level models

Detecting and quantifying small drawdown at observation wells distant from the pumping well greatly expands the characterized aquifer volume. However, this detection is often obscured by water level fluctuations such as barometric and tidal effects. A reliable analytical approach for distinguishing drawdown from nonpumping water-level fluctuations is presented and tested here. Drawdown is distinguished by analytically simulating all pumping and nonpumping water-level stresses simultaneously during the period of record. Pumping signals are generated with Theis models, where the pumping schedule is translated into water-level change with the Theis solution. This approach closely matched drawdowns simulated with a complex three-dimensional, hypothetical model and reasonably estimated drawdowns from an aquifer test conducted in a complex hydrogeologic system. Pumping-induced changes generated with a numerical model and analytical Theis model agreed (RMS as low as 0.007 m) in cases where pumping signals traveled more than 1 km across confining units and fault structures. Maximum drawdowns of about 0.05 m were analytically estimated from field investigations where environmental fluctuations approached 0.2 m during the analysis period.

Ground Water↗

USGS1998

Transport of agrichemicals to ground and surface water in a small central Indiana watershed

The occurrence, distribution, concentrations, and pathways of agrichemicals in water were investigated in the Sugar Creek watershed, a poorly drained agricultural watershed typical of many watersheds in the midwestern USA. Water samples from Sugar Creek, two tile drains, and 11 wells along a groundwater flowpath to Sugar Creek were collected between May 1992 and August 1996 and analyzed for N and pesticide compounds. Nitrate was the principal N species and pesticides were common in alluvial water-bearing units in the Sugar Creek floodplain. In the confined stratified drift aquifers, ammonia was the principal N species and pesticides were rare. Tile drains directly affected the water quality in Sugar Creek by transporting soil pore water and shallow groundwater containing high concentrations of nitrate (NO 3 ) and pesticides to the creek. When tile drains were flowing (typically December through July), elevated NO 3 concentrations (2–10 mg/L NO 3 N) in the creek correlated with high NO 3 concentrations (2–23 mg/L NO 3 N) in tile drains discharging to the creek. Likewise, with concentrations of atrazine and atrazine metabolites, seasonal trends in the tile-drain effluent were similar to seasonal trends in Sugar Creek. When tile drains went dry, NO 3 concentrations in the creek were low, indicating most groundwater discharge to the creek consisted of old or denitrified water. Trace levels of pesticides in the creek at low flow probably were the result of seepage from alluvial water-bearing units.

Indiana↗

USGS1995

Ground-water quality in northeastern St. Joseph County, Indiana

This report describes the ground-water quality of a 220-square-mile area in northeastern St. Joseph County, Indiana. Ground-water samples were collected from 30 monitoring wells at 20 sites during May 1992; the wells were screened in either a shallow or a deep sand and gravel aquifer. Samples were analyzed for general water-quality properties, nutrients, major ions, trace elements, industrial organic compounds, and pesticides. In general, the ground water is a slightly basic, very hard calcium bicarbonate water with a median dissolved-solids concentration of 310 milligrams per liter. The only constituent to exceed a U.S. Environmental Protection Agency Maximum Contaminant Level in the water samples was nitrate (which was exceeded in water samples from two wells). Concentrations of methylene-blue-active substances (detergent additives), chloride, and nitrate plus nitrite in the shallow aquifer were significantly higher (at the 0.05 probability level) than in the deep aquifer. The higher concentrations of these constituents in the shallow aquifer may be attributable to human activities. Concentrations of silica, ammonia, arsenic, antimony, barium, iron, and manganese in the deep aquifer were significantly higher than in the shallow aquifer; with the exception of ammonia, most or all of these constituents are probably from natural sources. No industrial organic compounds were detected in the water samples. Four pesticides - alachlor, carbofuran, metolachlor, and triazines - were detected in water samples; the highest pesticide concentration in a water sample was 1.0 microgram per liter of alachlor.

Indiana↗

USGS1993

Geohydrology and water quality of the Calumet aquifer, in the vicinity of the Grand Calumet River/Indiana Harbor Canal, northwestern Indiana

The water-table configuration of the Calumet aquifer in the vicinity of the Grand Calumet River/Indiana Harbor Canal in Lake County, northwestern Indiana, reflects the complexity of the shallow ground-water-flow system. Large depressions in the water table in sewered areas interrupt broad ground-water divides between rivers. The aquifer/stream interactions along the Grand Calumet River/ Indiana Harbor Canal are directly related to Lake Michigan water levels because of a direct connection of the Grand Calumet River/Indiana Harbor Canal to the lake. Fluctuations in lake levels and evapotranspiration result in reversals in ground-water flow near the river and canal that last from several hours to several months. Most of the water from the Calumet aquifer discharges into sewers, the Grand Calumet River/Indiana Harbor Canal, Lake Michigan, and Silurian carbonate bedrock. Model simulations of ground-water flow for the study area indicate that the Calumet aquifer discharges about 15 ft 3 /s (cubic feet per second) of ground water to sewers, about 10 ft 3 /s to the Grand Calumet River/Indiana Harbor Canal, and about 4 ft 3 /s to Lake Michigan along a 25-mile section of shoreline. Estimates of groundwater flow from the Calumet aquifer to the bedrock range from 0 to 10 ft 3 /s. Results of analyses of water samples collected from wells in five land-use types steel industry, petrochemical industry, commercial and light industry, residential, and parks were compared. The highest median concentrations of inorganic ions and the most detections of organic compounds generally occurred in water samples from wells on the steel and petrochemical land-use areas. Water samples collected from wells on the commercial and light industrial land-use areas generally had lower median chemical concentrations than the samples from the steel and petrochemical land-use areas and greater median concentrations than the samples from the residential and park land-use areas. Seven of 52 acid-extractable and base/neutralextractable organic compounds and 17 of 36 volatile organic compounds analyzed were detected in a total of 35 wells. Only 4 of the 88 organic analytes phenols, bis(2-ethylhexyl)phthalate, benzene, and toluene were detected in more than 5 of the 35 wells. A comparison of primarily inorganic-constituent data from the five land-use groups to inorganic-constituent data from sites known to be contaminated shows that constituent concentrations in ground waters from wells in the land-use areas generally are lower than those in ground water from contaminated areas. Abstract 1 Likewise, a comparison of inorganic-constituent data from the land-use groups to inorganic-constituent data from areas relatively unaffected by human presence shows that constituent concentrations in ground water from wells in the land-use areas generally are greater than those in ground water from the unaffected areas. Some documented but unaccounted for chemical loads in the Grand Calumet River are from ground water. Ground water probably contributes more than 10 percent of the total chemical load of ammonia, chromium, and cyanide to the Grand Calumet River. In comparison, about 1 to 3 percent of the total streamflow in the Grand Calumet River is from ground water. Of the four major groundwater sinks in the aquifer, the east branch of the Grand Calumet River and the Indiana Harbor Canal generally receive the greatest chemical loads from ground water, whereas Lake Michigan generally receives the smallest loads.

Indiana↗