MAP MAKING IN THE INFORMATION AGE

As the World rapidly enters the Information Age, the need for better and up-to-date maps becomes essential. People are finding it difficult, through the traditional written methods of communication, to absorb all the items with which they must deal during this new age. Basically, they are being overwhelmed with information. To handle partially this situation, more and more information is being presented graphically rather than textually. The map is a graphical communication medium by which a tremendous amount of information can be conveyed quickly. However, in order for the map to be an effective means of communication, it must be understood and it must be up-to-date and accurate.

For more than two decades British educator William Balchin has promoted the idea that K-12 school curricula should include geography with English and mathematics as foundation subjects. He notes that the four types of basic intelligence - verbal, social, numerical, and visual-spatial - relate to literacy, articulacy, numeracy, and graphicacy. He defines graphicacy as “the communication of spatial information that cannot be conveyed adequately by verbal or numerical means.” The tools of graphicacy are maps, diagrams, photographs, and other spatial documents.

Many maps are not accurate and are out-of-date, which can create problems for people using them to make decisions. It is a very difficult and time-consuming task to keep maps accurate and current. Like other map agencies throughout the world, the United States Geological Survey (USGS) is constantly striving to address this problem. In one map series alone it has to deal with the more than 54,000 large-scale topographic maps covering the 48 contiguous States and Hawaii. Remotely sensed imagery has become a valuable means for keeping maps accurate and up-to-date.

The goal of this instructional module is to present a methodology for updating the location and size of certain water bodies within a particular area of a USGS 7.5 minute topographic map. This methodology employs a Landsat TM (Thematic Mapper) data set, which covers a study area of 96.3 square miles or 249.5 square kilometers. The data set depicts conditions present on May 29, 1994 over the Kossuth, Indiana USGS topographic sheet. The USGS 7.5 Minute Topographic Quadrangle(Map)for Kossuth was originally produced in 1963, photorevised in 1980, and updated with minor revision in 1994.

The Kossuth USGS 7.5-minute topographic sheet is situated in the northern portion of Washington County, in southern Indiana. The Kossuth topographic sheet is typical of most of the USGS maps throughout the United States in that it covers a landscape which is not particularly spectacular but nonetheless interesting. The area is very rural with the major community being the hamlet of Kossuth (population 50, 1990). Some of the more appealing place names found on the map sheet, which reflect the southern Indiana milieu, are Potato Knob, Crossroads Church, Pumpkin Center, and Suicide Cave. Figure 1 is a generalized map (scale 1:250,000), which covers the Kossuth topographic sheet and beyond. Click on this map and the Kossuth 7.5-minute topographic sheet will appear. This is a large file, which may take a few monuments to display.

FIGURE 1

The most prominent landscape feature on the Kossuth USGS 7.5 minute topographic map is the Delaney Creek valley with the surrounding roughly dissected uplands. The valley floor is relatively flat and ranges from 550 to 600 feet in elevation. Deciduous trees grow along Delaney Creek, and corn and soybean fields cover the lower portions of the valley. Small fields of tobacco exist near the edges of the valley. The creek with its many small tributaries forms a classical dendritic drainage pattern. The uplands sharply rise from the valley floor and reach elevations of 850 to 900 feet. Mainly mixed forests of deciduous and evergreen trees cover them. Most of the area falls within the Jackson-Washington State Forest.

FIGURE 2

Figure 2 shows the typical small tobacco field with the uplands immediately behind it. This section of Indiana rests at the northern edge of the Kentucky tobacco region. Many old families in this section of Indiana trace their heritage back to Virginia by way of Kentucky. In such families tobacco has been a cash crop for generations and it has become as much a habit to grow it as to smoke and chew it.

FIGURE 3

In Figure 3 a cornfield spreads across the valley bottom. Note the sudden contrast in slope and elevation between the valley bottom and the uplands. Also, note the haze over the hills, which generally indicates the beginning of a late summer, afternoon thunderstorm. This type of haze makes it difficult to obtain sharp satellite imagery over this region in the late summer. In addition, the heavy cover of green crops reduces significantly the contrast between the valley floor and the uplands. The imagery used in the module was taken in late May when the crops in the fields have just started to appear and most of the land cover is still bare ground, which helps to differentiate the valley floor from the uplands. See Figure 6.

The Kossuth topographic map cuts across three physiographic regions. The Scottsburg Lowland extends along the northern edge of the map. This is a low (500 to 550 feet), flat area on which the Muscatatuck River meanders. Muscatatuck does not appear on the map but can be seen on the data set imagery. The Delaney Creek flows northward into the Muscatatuck, which eventually enters the East Fork of the White River and then the Wabash. The Norman Uplands occupy the major portion of the map area. Along the edge of the Norman Uplands and Scottsburg Lowland is the Knobstone escarpment, which has thin beds of soft fine-grained bluish-gray sandstones and shales. These sandstones and shales erode easily and are responsible for the deep dissections into the Norman Upland, which are clearly evident on the map. The southern portion of the map relates to the Mitchell Plain. This is a limestone plain, which dips quickly away from the Norman Uplands. As one drives south out of the Delaney Creek valley, one is crossing a divide where the Blue River starts its southern journey to the Ohio River. The Mitchell Plain with its limestone formations is a karst region with caves and sinkholes. Some of the small, dot size ponds on the bottom section of the topographic map are sinkholes with water in them. Figure 4 shows the major physiographic regions of southern Indiana with the political boundaries of Washington County superimposed on the three regions just described. It also identifies the location of the southern boundaries of the Illinoian and Wisconsin glaciers. The continental glaciers never covered a large section of southern Indiana, including most of Washington County.

FIGURE 4

The Kossuth topographic map shows several reservoirs nestled into the tributary valleys (hollows) entering the Delaney Creek valley. The reservoirs are colored purple on the map, which means that they were added to the map at a later date. The information on the reservoirs was obtained from aerial photographs and other sources but the information was not field checked. The reservoirs provide flood control for the Delaney Creek valley. With the steep slopes of the uplands and the frequent heavy summer thunderstorms associated with southern Indiana, small but devastating floods can occur suddenly in the valley area. The large reservoir (Figure 5) in Clay Hill Hollow is also used for recreation and forms the heart of Delaney Creek Park, which is maintained by the county. Note that the reservoirs are situated on the valley floor and are covering good farmland.

FIGURE 5

WATER BODIES

The Kossuth map was originally produced in 1963 and photorevised in 1980. As previously indicated, producing an accurate and up-to-date map is a long and complex process. It normally takes five years from the identification of a USGS 7.5 minute mapping project to the printing of the final map. This process requires a team of professionals and a series of closely coordinated steps. It used to take longer to produce a map because much of the needed information was gathered by field work and surveying, which are very expensive procedures. In recent decades the USGS has turned more toward aerial photography to obtain the required information. Most photographs used for the USGS’s topographic mapping program are now acquired through the National Aerial Photography Program (NAPP). NAPP flights are flown in a north-south direction along carefully determined flight lines. It takes 10 precisely positioned NAPP aerial photographs to provide the stereoscope coverage needed for each 7.5 minute map. At this coverage level NAPP photographs are mainly at the scale of 1:40,000. They are also generally black-and-white photographs. At this scale and with only black-and-white photographs an aerial photo interpreter might overlook some features. An examination of the satellite data set (Figure 6) being used in this module shows the location of several more reservoirs in the Delaney Creek valley, which do not appear on the 1980 photorevised map. These reservoirs could have been built after 1980, and thus, would not appear on the NAPP photographs. However, the map states that “minor revisions” were made in 1994, the year that the satellite data set was acquired. The minor revisions were noted on the map in the following manner:

“Photoinspected from 1992 source; no major culture or
drainage changes observed. Boundaries revised and names
verified 1994.”

The missing reservoirs probably were not constructed within the two year period between 1992, the date of the photo source, and 1994, the date of the satellite imagery. It would take several years to build and fill such reservoirs. It would also take time for vegetation to cover the earth dams and other disturbed lands around the reservoirs. Disturbed land surfaces would produce bright reflectances on the imagery. No such reflectances occur around these reservoirs indicating no recent construction. In addition, the minor revisions were dated 1994. Funds for building these reservoirs came from the Soil Conservation Service of the U.S. Department of Agriculture; thus, their existence had to be known. The problem most likely rests with the pressure and demand to provide up-to-date information, in this case map information, without giving full consideration to accuracy.

FIGURE 6

The objective of this module is to locate and measure these missing reservoirs using satellite imagery. Figure 6 is a false color composite image of the study area. The bright red areas indicate healthy, green vegetation, and correspond mainly to the forested uplands. The gray areas are related to bare agricultural fields found basically in the lowlands. The black areas are water bodies. Note that the dam areas immediately in front of the reservoirs are also bright red. These are earth dams with grass vegetation growing on them. Concrete dams would have a quite different reflectance. Two yellow boxes outline the reservoirs that do not appear on the topographic map. Check these areas with the full topographic map provided by clicking on Figure 1.

DATA SETS