Conference Papers

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...

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...

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...

The National Aerial Photography Program (NAPP) is jointly funded by Federal agencies and States that choose to participate in a 50-50 cost sharing cooperative arrangement. The NAPP is designed to acquire black-and-white (B&W) or color infrared (CIR) photography at a scale of 1:40,000. The status of NAPP flying, now going into the first year of its second 5-year cycle, is reviewed to...

A study to collect and analyze field measurements of bridge scour is being conducted by the U.S. Geological Survey in cooperation with the Federal Highway Administration. The primary objective of this study is to collect measurements of bridge scour as it occurs during floods to improve the ability to understand and predict scour processes. Scour measurements are classified as limited or...

The concepts that are the basis for the U.S. Geological Survey's National Water-Quality Assessment (NAWQA) program began forming in the early 1980's. By 1986, a pilot phase was initiated to test and refine assessment concepts and in 1991, the NAWQA program began a multi-year transition to a fully operational program. The goals of the program are to describe the status and trends in the...

New water-level sensing and recording instrumentation is being used by the U.S. Geological Survey for monitoring water levels, stream velocities, and water-quality characteristics. Several of these instruments are briefly described. The Basic Data Recorder (BDR) is an electronic data logger, that interfaces to sensor systems through a serial-digital interface standard (SDI-12), which was...

An empirical method has been devised to calculate the master recession curve, which is a mathematical expression for streamflow recession during times of negligible direct runoff. The method is based on the assumption that the storage-delay factor, which is the time per log cycle of streamflow recession, varies linearly with the logarithm of streamflow. The resulting master recession...

As part of a comprehensive geologic study of coastal Alabama and Mississippi, the U.S. Geological Survey is investigating coastal sediment transport in Mobile Bay and the adjacent shelf. Satellite imagery from the NOAA AVHRR is being used to provide data on the variability of spatial patterns in the near-surface suspended sediment concentration. This imagery is processed using...

No abstract available.