Page images
PDF
EPUB

The "Standard Land Use Coding Manual" (table 6), provides a four-digit categorization of land use developed mainly for urban and suburban areas in the United States. Ground observation and enumeration are essential; consequently, the system is not designed to be used with remote sensors. Inventory of the whole nation would be very expensive to complete and maintain. However, for limited areas where detailed land use information is needed, this system provides a useful framework. The first two levels are presented here. A further breakdown to levels III and IV for selected manufacturing and recreation categories is also presented to illustrate the detailed aspects of the system.

[blocks in formation]
[blocks in formation]

TABLE 6.—Continued

8 Resource production and extraction. 81 Agriculture.

82 Agricultural related activities.

83 Forestry activities and related services.

84 Fishing activities and related services.

85 Mining activities and related services.

89 Other resource production and extraction, NEC.

9 Undeveloped land and water areas.

91 Undeveloped and unused land area (excluding noncommercial forest development).

92 Noncommercial forest development.

93 Water areas.

94 Vacant flood area.

95 Under construction.

99 Other undeveloped land and water areas, NEC.

Other States besides Florida have developed classification systems and made land use maps in varying degrees of detail and sophistication. Below are some coastal State organizations that have made land use maps.

Alabama

Alabama Development Office Montgomery, Alabama 36104

California

California Department of Water Resources Sacramento, California 95814

Connecticut

State of Connecticut

Planning and Budgeting Division

340 Capital Avenue

Hartford, Connecticut 06115

Delaware

Director, State Planning Office

Office of the Governor

Dover, Delaware 19901

Maryland

Maryland Department of State Planning 301 W. Preston Street

Baltimore, Maryland 21201

Massachusetts and Rhode Island

Department of Forestry and Wildlife Management
Holdsworth Hall

University of Massachusetts
Amherst, Massachusetts 01002

Minnesota

Minnesota State Planning Agency St. Paul, Minnesota 55101

New York

State of New York

Office of Planning Services

488 Broadway

Albany, New York 12207

The coastal States that are completely mapped under 50-50 cost-sharing agreements with USGS are Louisiana and Florida. Mapping is in progress under similar agreements with Alabama, Georgia, and Pennsylvania.

LAND USE AND LAND COVER MAPPING

Land use maps are usually the result of an inventory. The maps may be made for a specific purpose and are not necessarily in reproducible form for public use. The lack of comparable land use maps. for extensive areas has often been a handicap to the planning process, at least at the Federal level and usually at the regional and State levels.

USGS has begun nationwide land use mapping to provide a systematic and comprehensive collection of land use and land cover data appropriate for large areas which are expensive to map in great detail. Figure 36 shows the current status of this mapping.

Specific products provided by the land use mapping program are:

[ocr errors][ocr errors]

Maps at 1:250,000 scale showing the present land use at level II of the classification system developed by USGS in conjunction with Federal and State agencies and others. For each of the land use/land cover maps produced, overlays are also compiled to show Federal land ownership, river basins and subbasins, counties, and census county subdivisions. State land ownership is shown when USGS has the appropriate information from the State.

Land use and land cover data are keyed to the enlarged culture and drainage color-separation plates of the standard USGS 1:100,000- or 1:250,000-scale topographic sheets. The minimum mapping unit for urban and built-up uses, water areas, confined feeding operations, other agricultural land, and strip mines, quarries, and gravel pits is 10 acres. The minimum mapping unit for other categories is 40 acres. Federal land holdings are shown for tracts of 40 acres or larger, and State land holdings are similarly delineated when data are available.

Selected experimental demonstration land use and land cover maps at 1:24,000 or 1:50,000 scale are also being prepared for selected areas. These maps show how land use and land cover mapping at a regional scale can be related to more detailed mapping at larger scales. Computerized graphic displays and statistical data on current land use and land cover will be

[graphic][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed]

FIGURE 36.-Land use/land cover map production status in the United States.

available through this program for use with other data. Statistical data are compiled by counties, areas of Federal ownership, river basins and subbasins, and statistical units such as census tracts or other census county subdivisions.

Land use and land cover data are digitized in polygon format (each individual area comprises a polygon). Conversion of land-use polygons to land-use grid cells of varying sizes can be made when desired.

Because of the dynamics of land use, the emphasis for preparing and distributing all products is on supplying information to the users as soon as possible. Research in data and information requirements, inventory methods and data use, and interpretative studies is also being carried out under the USGS land use mapping program. The program

uses advanced technology, NASA high-altitude photographs, aerial photographs acquired for USGS topographic mapping, and Landsat data.

For more information on land use and land cover mapping, contact:

Chief Geographer

U.S. Geological Survey MS 710 National Center Reston, Virginia 22092 Telephone: 703-860-6344

The rest of this section concentrates on the general aspects of land-use mapping, such as source material, minimum size, and accuracy. Procedures are not described in the handbook because several books and manuals are already available (see "Selected references").

96

The types and amounts of land use and land cover information that can be obtained from different sensors depend on the altitude and the resolution of each sensor. Presently, no one sensor or system will produce good data at all altitudes. Each source and application of remote-sensing data must be evaluated solely on the basis of its qualities and characteristics. Data are usually transferred to a base map, although a base map is difficult to use without extracting some additional data from it. Topographic maps, road maps, and detailed city maps generally contribute detail beyond the capabilities of the remote-sensor data.

Different sensors provide data at varying resolutions depending on altitude and scale. In general, the following relationships are true for a camera with a 6-in focal length.

Level

I

II

III

IV

Typical data characteristics

Landsat type data.

High-altitude data at 12,200 m (40,000 ft) or
above, (less than 1:80,000 scale).
Medium-altitude data obtained between 3,000
and 12,200 m (10,000 and 40,000 ft) (1:
20,000 to 1:80,000 scale).
Low-altitude data taken below 3,000 m (10,000
ft) (more than 1:20,000 scale).

Although land use data obtained at any level certainly is neither restricted to a particular user group nor to a particular presentation scale, information at levels I and II (fig. 37) usually interests users who need data on a nationwide, interstate, or statewide basis. Generally, more detailed land use and land cover data, such as that categorized at levels III (fig. 38) and IV is used more frequently by those who need and who generate local information at the intrastate, regional, county, or municipal level.

The relationship between the categorization level and the data source is not intended to restrict users to particular scales, either in the original source from which the land use information is compiled or in the final graphic. For example, level I land use information, while efficiently and economically gathered over large areas by a Landsat-type satellite or from high-altitude imagery, could also be interpreted from conventional large-scale aircraft imagery or compiled by ground survey. The same information can be displayed at a wide variety of scales ranging from a standard 1:24,000-scale topographic map to the much smaller 1:1,000,000-scale orbital imagery overlay. Similarly, several level II categories have been interpreted from Landsat data although they can be obtained more accurately from

high-altitude photographs at present. Some level III and IV land use and land cover data can also be obtained from high-altitude imagery. This categorization level can also be presented at a wide range of scales. However, as the more detailed categorization levels are used, more dependence must be placed on higher resolution remote-sensor data and supplemental ground surveys.

The principal remote-sensor source for level II data is high-altitude color infrared photographs. Scales smaller than 1:80,000 are characteristic of high-altitude photographs, although scales from 1:24,000 to 1:250,000 generally have been used for final map products.

The same photographs used to construct or update 1:24,000-scale topographic maps or similarly scaled orthophotoquads are potential sources for inventorying land use and land cover. The orthophoto bases permit rapid interpretation of level I and II information at relatively low cost. However, the cost of acquiring more detailed levels of land use and land cover data may be too expensive to include the data on large-scale maps.

In most land use applications, USGS is interested in the smallest area that can be recognized to have an interpretable type of land use or land cover. The smallest area that can be recognized depends not only on the type and characteristics of the imaging system, but also on the order of image generation (how many reproduction stages is the study image from the original). The user needs the most recent information available to determine the resolution parameters of the system.

The smallest area that can be placed in a land use category also depends on the compilation and publication scales. Sometimes land uses cannot be identified with the accuracy level needed for the smallest unit being mapped. At other times, specific land uses can be identified, although they are too small to be mapped. For example, farmsteads are not usually distinguished from other agricultural land uses when mapping at more generalized classification levels. On the other hand, On the other hand, these farmsteads may be interpretable at more detailed levels, but they may be too small to be represented at the final scale. Similar situations may arise when using other categories.

When a map is the medium for presenting land use data, any unit area smaller than 2.5 mm (0.1 in) on a side is difficult to represent. Smaller areas also cause legibility problems for the map reader. Users of computer-generated graphics are similarly constrained by the computer printout size.

[ocr errors][ocr errors]
[graphic][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][merged small][subsumed][subsumed][subsumed][subsumed][merged small][subsumed][subsumed][subsumed][subsumed][subsumed][ocr errors][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][merged small][merged small][merged small][merged small][merged small][merged small][merged small][subsumed][ocr errors][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][merged small][subsumed][merged small][merged small][merged small][merged small][subsumed][subsumed][subsumed][subsumed][subsumed][merged small][merged small][subsumed][merged small][subsumed][subsumed][subsumed][subsumed][merged small][subsumed][subsumed][subsumed][merged small][subsumed][subsumed][subsumed][merged small][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][merged small][merged small][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][merged small][subsumed][subsumed][merged small][merged small][ocr errors][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][merged small][merged small][subsumed][subsumed][subsumed][merged small][subsumed][merged small][subsumed][subsumed][subsumed][merged small][subsumed][subsumed][subsumed][merged small][merged small][merged small][merged small][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][ocr errors][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][merged small][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][merged small][merged small][merged small][subsumed][subsumed][subsumed][subsumed][merged small][merged small][merged small][subsumed][subsumed][subsumed][subsumed][subsumed]

FIGURE 37.-Level II land use and land cover in an enlarged part of the northeast quarter of the USGS Indianapolis, Ind.-Ill., 1:250,000-scale quadrangle base map. The area outlined in the center is shown in figure 38.

There are three types of accuracy considerations for mapping land use and land cover by remote sensing. First is the accuracy with which areas are delineated to show the exact outline as it exists on the Earth's surface. The compilation scale will have some effect; however, using photographic source materials will make the outline as precise as the scale allows. Second is the interpretation accuracy. Various field checks or field validation techniques

and processes can establish interpretation accuracy. An accuracy of 85 percent or better can be achieved by using qualified interpreters. Third is the positional accuracy associated with the plotting base. Generally, the larger the scale, the better the positional accuracy. Rectified photomosaics and largescale topographic quadrangles have very good positional accuracy.

« PreviousContinue »