1987 GIS Spatial Analysis Tools Short

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A 1987 video from the USGS Earth Resources Observation and Science (EROS) Center on geospatial analysis tools - short version


Date Taken:

Length: 00:16:13

Location Taken: Sioux Falls, SD, US


The U.S. Geological Survey uses advanced computerized geographic information systems  valuable tools for manipulating and analyzing vast amounts of spatial data for solving complex Earth science and natural resource issues. The use of geographic information systems, or GIS, has revolutionary implications for the way the Geological Survey conducts research and presents results. As the nation’s primary producer of cartographic, geographic, hydrologic, and geologic data, the Survey is using advanced GIS technologies to greatly improve its ability to perform traditional missions of Earth science data collection, research, and information retrieval. The USGS and other bureaus and offices of the Department of the Interior have established a number of digital spatial databases that are being used in geographic information systems nationwide. These include the National Digital Cartographic Database, Digital Line Graph, Digital Elevation Model, and Land Use and Land Cover Data, the National Coal Resources Data System, the Geographic Names Information System, the Water Data Storage and Retrieval System, and the Rock Analysis Storage System. The Geological Survey is increasingly being asked to serve as a central repository for digital Earth science data and to be an authority on GIS techniques for  arranging, displaying, and analyzing diverse data about such critical issues as the nation’s energy and mineral potential, the assessment of risks from natural hazards, and questions about water supply quantity and quality. Because GIS technology allows scientists to process and inter-relate many more kinds of data than were previously possible, GIS applications research provides new scientific methods to investigate these issues. Although GIS technology has been in use for more than 10 years, the acceptance level and use of this spatial analysis tool has remained low because of a lack of available detailed base map and digital thematic data. The Geological Survey is continuing efforts to merge its existing spatial databases to provide convenient and cost-effective Earth science natural resources data. In particular, transportation and hydrologic features digitized from 1- to 100,000-scale base maps serve not only as a fundamental database for GIS studies, but also as a catalyst for the addition of thematic data. The director of the U.S. Geological Survey, Dr. Dallas Peck, describes a joint project between the USGS and the State of Connecticut, demonstrating the tremendous potential of geographic information systems. - In 1984, the U.S. Geological Survey and the State of Connecticut’s Natural Resources Center agreed to evaluate the use of geographic information systems – GIS technology – to apply Earth science data to solve real-life problems in the state of Connecticut. The project was an outgrowth of an ongoing cooperative program between the USGS and the State of Connecticut to gather Earth-related information on geology, soils, water, land use, land cover, and land features. Members of the Connecticut Natural Resources Center combined their expertise with scientists from the U.S. Geological Survey to develop a GIS for this demonstration. Building on a cartographic base, this involved capturing, storing, updating, analyzing, and displaying computerized natural resources data to solve such problems as well siting and industrial development. The project ultimately demonstrated how a cooperative approach such as this could be used to address natural resource questions at federal, state, and local levels. - Connecticut natural resource analyst Sandy Prisloe described some of the complex environmental questions answered during the course of the project. - We wanted to see how we could use the various types of data layers in a geographic information system to answer questions about the suitability of areas for well siting. We wanted to see if we could use the geographic information system to assist in development of data for three-dimensional groundwater flow models. We have some simple applications that looked at how a GIS can calculate estimated seven-day, 10-year low flows for drainage basins in Connecticut. And lastly, we looked at how a geographic information system can do sort of a site analysis and evaluate areas for industrial siting. - In order to find the answers to these questions, USGS scientists entered data into the GIS from existing digital databases and from digitizing information from hard-copy maps. Digitization was performed at two locations – the Geological Survey’s Eastern Mapping Center and the Earth Resources Observation Systems – EROS Data Center. The primary GIS used was the ArcInfo geographic information system. Roughly one-third of the database was derived from existing digital information that was available from the Geological Survey. These data include 1- to 24,000-scale digital line graphs, land use and land cover, political boundaries, hydrography, transportation, and state and federal lands. Four application models were developed to test the usefulness ofthis GIS in actualgovernment agency programs. In the next few minutes, Sandy Prisloe and U.S. Geological Survey geographer Larry Batten will demonstrate how these models helped to evaluate the effectiveness of GIS technology in merging data from a variety of sources for use in research, planning, management, and regulatory programs. - The series of maps that we’re going to be showing here represent one of the demonstration applications that we developed as part of the Connecticut project. The map that’s on the screen now represents the two-quadrangle area. That’s the box on the interior here. And that represents a UTM projection of the two quadrangles. The information being displayed on the screen are water utility service areas. The area that we concentrated on for this well siting application was the Somers Water Company shown up here in blue. And you’ll notice that there is a line around the water company. That represents a half-mile buffer. One of the operations that we used within the GIS was to create a buffer around the water utility. What we wanted to do was to look for sites that had a high potential for groundwater development. And we wanted to only look a certain distance away from th existing water utility, so we chose a distance of a half-mile, figuring that was a reasonable distance to look within. So the area that we’ll be showing you maps of represent that half-mile area surrounding the existing service area for the Somers Water Company. The map that’s coming up on the screen now represents an enlargement of that half-mile buffered area. It represents a land use map that was developed as a joint project between the USGS and the State of Connecticut. It’s a detailed level III land use classification. It was developed primarily to look at some of the hydrologic characteristics of the land use as well as what the – what the current land uses were and what the current land cover is. What we wanted to do here was to look at this map and use the geographic information system to eliminate areas that had existing land uses that would be incompatible with water supply development. So what we did is we instructed the GIS to re-select only land uses which we deemed to be suitable for groundwater development. And those were primarily areas which are forested areas or wetland areas. Agricultural lands, residential lands – any type of developed areas, we eliminated from consideration. This map represents just the areas that are suitable land uses from a groundwater development point of view for this application. We wanted to look at some of the other characteristics of the land surface to find out what was going on that we – has a impact on the well – potential well sites. And so we looked at mapped pollution sources. And this map represents, within the area that we’re – the entire area that we are considering, the six known pollution sites. And what we wanted to do was to say we’re not going to look for – or, allow a well to go in within – in this case, we chose a distance of 500 meters of those pollution sites. The map that comes up on the screen now represents an area, shown in red, that was created by buffering those pollution sources. All the pollution sources were treated the same. We could have chosen to do it differently and create different-size buffers based on the toxicity of the – of the source – something of that nature. But what we were interested in here – doing was just showing that you can use the geographic information system to create an area around a point source and then eliminate that area from consideration. So Larry – the next map that Larry will show represents – in the same color now, it represents those areas which have a suitable land use and are not within 500 meters of a known pollution source. And you’ll notice, down the middle of the map on the screen, that a large – or, a large amount of the area, which was on the previous slide represented in red, has been eliminated. We also wanted to look at not only point sources of pollution – we also wanted to look at streams in the area which are waste-receiving streams. And the light blue lines here represent streams which are classified as class B or class C streams in Connecticut. And what that means is that there is a permitted discharge, or there’s a landfill that leaches into the stream. And we said, in this case, we don’t want to see a well going in within 100 meters of the stream. We wanted to make sure hat there would be no induced infiltration to a well if it were placed next to a stream that was a polluted stream. So we created a 100-meter buffer around the streams. And, as you saw in the previous example, we eliminated these areas from consideration as well. What we were essentially doing, or what we are doing here, is going through a series of binary  operations. Is it good? Is it bad? And if it’s bad, we’re going to throw it out and not consider it any further. We also looked at some other characteristics of the land surface, such as zoning. Also the location of existing public water supply wells and did a similar type of operation with them. After we had done an analysis of what’s going on on the land surface, we then wanted to look at the hydrogeology. What was there that would be suitable? What areas would be suitable from a water supply point of view? And this map represents the detailed surficial material mapping for the area within a half-mile of the service area. And what we were interested in here was looking at the surficial materials in terms of their texture. We only wanted to consider areas which were coarse-grain stratified drift. And I think most of the coarse-grain materials pretty much run down through the sand and gravel deposits in the middle of the – of the area. What we were interested in were only those areas which had a saturated thickness of greater than 40 feet and had coarse-grain materials. And so what we’ve gone through here is a very quick analysis in which we looked at land surface phenomena and characteristics of the landscape that would prohibit, or preclude, the development of a water supply well. And we then looked at the hydrogeology. What areas would be suitable based on the availability of groundwater supplies? We take all of those data sets and the various overlays that were developed, put them together, subtract areas from consideration, keep areas that are good from a hydrogeologic point of view. We ended up with six sites, which are shown here in the blue, as possible sites that would merit further field investigation for water supply wells. And what this last map shows is not only the six sites that would be suitable, but also we have superimposed, or overlaid with that, the road network from the digital line graph data in red. And in blue, the hydrography information. And the names that are on there are from the Geographic Names Information System. So we have sort of a composite map that shows the final results of this particular demonstration anyway, of a variety of different data sets put together. - And what I’ll do now is zoom into this area to show the detail that you can maintain within that system. So you can actually come down and, were you to go in the field to identify this lot, you could actually know which roads intersected that in the area. - Geographic information systems applications are numerous and diverse. Federal agencies use these spatial analysis tools to manage national parks, national forests, wildlife refuges, and federal mineral and petroleum resources. In addition to Connecticut, other states and local governments use geographic information systems to plan industrial development and recreational activities. Private organizations find them useful to target potential market areas and to determine site suitability for commercial development. If development and management of our water and other finite natural resources are to be based on the best available information, it’s crucial that this knowledge be transferred to policymakers in a timely, understandable, and cost-effective manner. Geographic information systems provide a powerful tool for collecting, manipulating, displaying, and analyzing large volumes of spatially referenced data. The U.S. Geological Survey’s Geologic, Water Resources, Information Systems, and National Mapping divisions continue to combine their expertise to lead in developing techniques for applying advanced GIS technology to solve resource problems encountered by government, private industry, and the public. For more information, contact the U.S. Geological Survey, GIS Laboratory, 567 National Center, Reston, Virginia, 22092.