Geology topics

D.J. Downing

Publications and source records attributed to D.J. Downing.

6 recordsLinked to original sources

USGS1993

Recent growth increases in old-growth longleaf pine

Longleaf pine ( Pinus palustris Mill.) tree-ring data were obtained from an old-growth stand located in Thomas County, Georgia. The tree-ring chronology from the pine stand is composed of a collection of cores extracted from 26 trees ranging in age from approximately 100 to 400 years. These cores were prepared, dated, and measured, and the resulting data were examined with dendrochronological and statistical techniques. Beginning in approximately 1950 and continuing to the present, annual increments of all age classes examined in this study have increased, resulting in an average annual ring increment approximately 40% greater in 1987 than in 1950. When compared with expected annual increment, the increase for 100- to 150-year-old trees is approximately 45%, while the increase for 200- to 400-year-old trees is approximately 35%. In terms of stand-level aboveground biomass accumulation, the increased growth has resulted in approximately 5% more biomass than expected. The increased growth cannot be explained by disturbance; stand history; or trends in precipitation, temperature, or Palmer drought severity index over the last 57 years. Increased atmospheric CO 2 is a possible explanation for initiation of the observed trend, while SO x and NO x may be augmenting continuation of this phenomenon.

Georgia↗

USGS1979

Hydrologic data, 1974-77, Stovepipe Wells Hotel area, Death Valley National Monument, Inyo County, California

Ground-water levels in most wells did not change significantly from 1974 to 1977 in the Stovepipe Wells Hotel area. The average water-level decline was less than 0.10 foot between August 1974 and August 1977 in 10 observation wells. Water-level contours show a depression centered on the two pumping wells, but this depression existed before the National Park Service started pumping its well. The chemical quality of the ground water is poor. Dissolved-solids concentrations in water samples ranged from 2,730 to 6,490 milligrams per liter. Analyses of water samples from two wells showed large changes in some constituents from 1976 to 1977. Water-quality monitoring will continue at these sites to verify the changes. Streamflow in Salt Creek has been monitored since February 1974. Base flow is seasonal, being 0.10 to 0.20 cubic foot per second during the summer and as much as three times that amount during the winter. Two chemical analyses of water from Salt Creek, representing summer and winter flow conditions, show large differences for many constituents.

California↗

USGS1978

Summary of water resources for the Campo, Cuyapaipe, La Posta, and Manzanita Indian Reservations and vicinity, San Diego County, California

Since 1945, precipitation and runoff in California on the Campo, Cuyapaipe, La Posta, and Manzanita Indian Reservations and surrounding areas generally have been below normal, and ground-water levels are declining. Most of the water is of excellent quality. The analysis of water from one well on the Campo Reservation indicates a concentration of nitrate that exceeds the recommended limit established in 1972 by the U.S. Environmental Protection Agency. Most wells and springs in the study area yield water for domestic purposes. The yields range from less than 1 gallon per minute to 210 gallons per minute. Most of the water is produced from shallow aluvial-filled channels or from consolidated rocks that are deeply weathered locally or highly fractured. The well data show that insufficient water is available on the four reservations for large-scale irrigation. (Woodard-USGS)

Open-File Report↗

USGS1978

Ground-water data, 1974-76, Indian Wells Valley, Kern, Inyo, and San Bernardino Counties, California

Water-level measurements were made annually in 115 wells in Indian Wells Valley, Kern, Inyo, and San Bernardino Counties, Calif., in 1974-76. In the Inyokern area the average water-level decline was 2.0 ft for two wells between October 1973 and November 1976. In the intermediate area the average decline was 6.2 ft for five wells between October 1973 and December 1976. In the Ridgecrest area the average decline was 4.5 ft for four wells between October 1973 and December 1976 but was 10.3 ft for one well during the same period. Reported metered ground-water pumpage from Indian Wells Valley totaled 14,400 acre-ft in 1974, 14,500 acre-ft in 1975, and 14,100 acre-ft in 1976. These figures may not completely reflect the total pumpage from the basin due to changing patterns of land use and new pumping sources. Chemical analyses were made of 102 water samples collected from 42 wells during 1974-76. The analyses show large variance of quality of ground water in Indian Wells Valley. (Woodard-USGS)

Open-File Report↗

USGS1978

Ground-water data for 1976-77 in Joshua Tree National Monument, California

A continuing study of ground water in Joshua Tree National Monument shows that during 1976-77 water levels fluctuated seasonally; slight declines were detected in the Oasis of Mara and the Pinto Basin. Water quality was generally good, with a high concentration of fluoride in one well in the southern part of the Monument.

California↗

USGS1977

Ground-water data for 1974-75 in Joshua Tree National Monument, California

This report, prepared at the request of the National Park Service, is part of a continuing inventory by the U.S. Geological Survey of general geohydrologic conditions at Joshua Tree National Monument, California. Tables of data for 1974-75 includes chemical analyses of ground water from selected wells and pumpage by Kaiser Steel Corporation from Pinto Basin. The table for yearly pumpage totals by Kaiser Steel Corporation includes years 1960-75. Water-level measurements are included for 22 observation wells. (Woodard-USGS)

Open-File Report↗