Conference Papers

No abstract available

Analytical data for stable isotopes in ground water from beneath Yucca Mountain, when examined in map view, show areal patterns of heterogeneity that can be interpreted in terms of mixing of at least three end members. One end member must be isotopically heavy in terms of hydrogen and oxygen and have a young apparent 14C age such as water found at the north end of Yucca Mountain beneath Fortymile

The prediction of large-scale coastal change is an extremely important, but distant goal. Here we describe some of our initial efforts in this direction, using historical bathymetric information along a 150 km reach of the rapidly evolving barrier island coast of Louisiana. Preliminary results suggest that the relative sea level rise rate, though extremely high in the area, has played a secondary

The geologic framework of the north-central Gulf of Mexico shelf is composed of multiple, stacked, delta systems. Shelf and nearshore sedimentary facies were deposited by deltaic progradation, followed by shoreface erosion and submergence. A variety of sedimentary facies has been identified, including prodelta, delta fringe, distributary, lagoonal, barrier island, and shelf sand sheet. This study

Louisiana's coastal wetlands support a large percentage of the nation's seafood and fur industries, vast deposits of oil and natural gas, habitat for thousands of species of plants and animals, winter nesting grounds and migratory paths for numerous waterfowl, and many recreational resources enjoyed by residents and tourists. Louisiana's wetlands also have the highest rates of coastal erosion and

In support of beach-stability research, bedload and suspended sediment were measured during a steady flow of 5,880 ft3/s and receding flows from 12,100 to 5,660 ft3/s in the Colorado River above National Canyon, near Supai, Arizona, October 7-12, 1989. During steady flows, 75 percent of the mean total-sediment discharge of 128 t/d was in suspension and about half the total-sediement load was finer

About 4,000 gravity stations have been obtained at Yucca Mountain and vicinity since the beginning of radioactive-waste studies there in 1978. These data have been integrated with data from about 29,000 stations previously obtained in the surrounding region to produce a series of Bouguer and isostatic-residual-gravity maps of the Nevada Test Site and southeastern Nevada. Yucca Mountain is characte

By the mid-1990's, the U.S. Geological Survey expects to produce spatial data according to its new data model, Digital Line Graph-Enhanced (DLG-E). This new data model currently defines more than 200 unique feature types that describe the geographic phenomena portrayed on the series of 1:24,000-scale topographic maps. Characteristics of features are encoded as attributes, and linkages between feat

The key to objectively measuring the benefits of GIS use is to realize that there are two different types of benefits and that different techniques must be used to measure each. Efficiency benefits occur when the same task previously done without the GIS can be done less expensively with the GIS. Effectiveness benefits occur when the GIS allows completion of a task that would not have been done wi

No abstract available.

No abstract available.

An aerial videotape mapping system was used to monitor spatial and temporal variability of the coastal morphology along the Isles Dernieres barrier shoreline. Between 1984 and 1989, nine sequential annual and post-hurricane aerial videotape surveys were flown covering periods of prolonged fair weather, hurricane impacts, and subsequent post-storm recovery. Morphologic time series were developed to