A knowledge of land use and land cover is important for many planning and management activities concerned with the surface of the earth. The use of
panchromatic, medium scale aerial photographs to map land use has been an accepted practice since the 1940s. More recently, small scale aerial photographs and satellite images have been utilized for land use/land cover mapping of large areas.The term land cover relates to the type of feature present on the surface of the earth. Corn fields, lakes, maple trees, and concrete highways are all examples of land cover types. The tel:m land use relates to the human activity or economic function associated with a specific piece of land. As an example, a tract of land on the fringe of an urban area may be used for single-family housing.Depending on the level of mapping detail, its land use could be described as urban use, residential use, or single-family residential use. The same tract of land would have a land cover consisting of roofs, pavement, grass, and trees. For a study of the socioeconomic aspects of land use planning (school requirements, municipal services, tax income, etc.), it would be important to know that the use ofthis land is for single-family dwellings. For a hydrologic study of rainfall-runoff characteristics, it would be important to know the amount and distribution of roofs, pavement, grass, and trees in this tract. Thus, a knowledge of both land use and land cover can be important for land planning and land management activities. The USGS has devised a land use and land cover classification system foruse with remote sensor data . The concepts discussed in the remainder of this section are based principally on this publication. Ideally, land use and land cover information should be presented on separate maps and not intermixed as in the USGS classification system. From a practical standpoint, however, it is most efficient to mix the two systems when remote sensing data form the principaldata source for such mapping activities. While land cover information can be directly interpreted from appropriate remote sensing images, information about human activity on the land (land use) cannot always be inferred directly from land cover. As an example, extensive recreational activities covering large tracts of land are not particularly amenable to interpretation from aerial photographs orsatellite images. For instance, hunting is a common and pervasive recreational use occurring on land that would be classified as some type of forest, range, wetland, or agricultural land during either a ground surveyor image interpretation. Thus, additional information sources are needed to supplement the land cover data. Supplemental information is also necessary for determining the use of suchlands as parks, game refuges, or water conservation districts that may have land uses coincident with administrative boundaries not usually identifiable on remote sensor images. Recognizing that some information cannot be derived from remote sensing data, the USGS system is based on categories that can be reasonably interpreted from imagery. The USGS land use and land cover classification systemwas designed according to the following criteria: (l) the minimum level of interpretation accuracy using remotely sensed data should be at least 85 percent, (2) the accuracy
of interpretation for the several categories should be about equal, (3) repeatable or repetitive results should be obtainable from one interpreter to another and from one time of sensing to another, (4) the classificationsystem should be applicable over extensive areas, (5) the categorization should permit land use to be inferred from the land cover types, (6) the classification system should be suitable for use with remote sensor data obtained at different times of the year, (7) categories should be divisible into more detailed subcategories that can be obtained from large scale imagery or ground surveys, (8)...
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