Geology topics

G.J. Gonthier

Publications and source records attributed to G.J. Gonthier.

3 recordsLinked to original sources

USGS1996

Ground-water-flow conditions within a bottomland hardwood wetland, eastern Arkansas

Water levels were measured monthly at 9 staff gages and 35 wells along two transects within the Black Swamp bottomland hardwood wetland and perpendicular to the Cache River in eastern Arkansas from December 1989 to September 1992 in order to (1) describe the ground-water-flow conditions at locations within a bottomland hardwood wetland and (2) determine the relation between the frequency of different ground-water-flow conditions and physical characteristics within the wetland. Three ground-water-flow conditions predominated at various times in the Black Swamp: (1) discharge of water from the alluvial aquifer to the wetland, (2) recharge of water from the wetland into the alluvial aquifer, and (3) flow of water from the wetland into the alluvial aquifer and then to the nearby Cache River (local flow). Analyses of hydraulic head differences between surface and ground water indicate that discharge occurred 31% of the measurement times at both transects. Recharge occurred 39% of the measurement times and tended to occur more often at locations that are far from the Cache River and that overlie low ground-water levels in the lower part of the alluvial aquifer. Local ground-water flow occurred 28% of the measurement times and tended to occur more often at locations close to the Cache River. Ground-water pumpage results in water-level declines in the lower part of the alluvial aquifer near the Black Swamp wetland. When compared with an area not affected by pumping, these lower ground-water levels increased the frequency of recharge of Black Swamp water into the alluvial aquifer by nearly a factor of 7, decreased the frequency of local ground-water flow to the Cache River to less than half, and decreased the frequency of discharge by about 22%.

Arkansas↗

USGS1996

Ground-water flow patterns and water budget of a bottomland forested wetland, Black Swamp, eastern Arkansas

The U.S. Geological Survey, working in cooperation with the U.S. Army Corps of Engineers, Waterways Experiment Station, collected surface-water and ground-water data from 119 wells and 13 staff gages from September 1989 to September 1992 to describe ground-water flow patterns and water budget in the Black Swamp, a bottomland forested wetland in eastern Arkansas. The study area was between two streamflow gaging stations located about 30.5 river miles apart on the Cache River. Ground-water flow was from northwest to southeast with some diversion toward the Cache River. Hydraulic connection between the surface water and the alluvial aquifer is indicated by nearly equal changes in surface-water and ground-water levels near the Cache River. Diurnal fluctuations of hydraulic head ranged from more than 0 to 0.38 feet and were caused by evapotranspiration. Changes in hydraulic head of the alluvial aquifer beneath the wetland lagged behind stage fluctuations and created the potential for changes in ground-water movement. Differences between surface-water levels in the wetland and stage of the Cache River created a frequently occurring local ground-water flow condition in which surface water in the wetland seeped into the upper part of the alluvial aquifer and then seeped into the Cache River. When the Cache River flooded the wetland, ground water consistently seeped to the surface during falling surface-water stage and surface water seeped into the ground during rising surface-water stage. Ground-water flow was a minor component of the water budget, accounting for less than 1 percent of both inflow and outflow. Surface-water drainage from the study area through diversion canals was not accounted for in the water budget and may be the reason for a surplus of water in the budget. Even though ground-water flow volume is small compared to other water budget components, ground-water seepage to the wetland surface may still be vital to some wetland functions.

Water-Resources Investigations Report↗

USGS1990

Ground-water levels in Arkansas, spring 1989

Groundwater level measurements were made in 527 wells in Arkansas in the spring of 1989. These data are listed in tables by aquifer and then by county. For each well, the altitude of the land surface, the date of measurement, the depth to the water surface, and the altitude of the water surface are reported. Also reported are the net changes in water levels between 1988 and 1989 and between 1984 and 1989. This report also contains maps showing the average water level change, by county, between the years 1984 and 1989 for the aquifers in the Quaternary deposits and in the Sparta Quaternary deposits and in the Sparta and Memphis Sands. The aquifers in the Quaternary deposits and in the Sparta and Memphis Sands are important in eastern and southern Arkansas for agricultural, municipal, and industrial use. Water level data contained in this report showed an average decline of 1.86 ft in the aquifer in the Quaternary deposits, for the 27 most heavily irrigated counties of eastern Arkansas, and an average decline of 4.06 ft in the aquifer in the Sparta and Memphis Sands between the years 1984 and 1989. (USGS)

Open-File Report↗