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Region
"Regions" redirects here. For the financial institution, see Regions Financial Corporation.
For the Amtrak train, see Regional (Amtrak). For the forest in Tolkien's legendarium, see Region (Middle-earth).
Region is a geographical term that is used in various ways among the different branches of geography. In general, region medium-scale area of land or water, smaller than the whole areas of interest (which could be, for example, the world, a nation, a river basin, mountain range, and so on), and larger than a specific site or location. A region can be seen as a collection of smaller units (as in "the New England states") or as one part of a larger whole (as in "the New England region of the United States"). Regions are areas and or the spaces used in the study of geography. A region can be defined by physical characteristics, human characteristics and functional characteristics. As a way of describing spatial areas, the concept of regions is important and widely used among the many branches of geography, each of which can describe areas in regional terms. For example, ecoregion is a term used in environmental geography, cultural region in cultural geography, bioregion in Biogeography, and so on. The field of geography that studies regions themselves is called Regional geography. Regions are conceptual constructs and, thus, may vary among cultures and individuals. Natural regionsIn the fields of physical geography, ecology, biogeography, zoogeography, and environmental geography, regions tend to be based on natural features such as ecosystems or biotopes, biomes, drainage basins, mountain ranges, soil types, and so on. EcoregionsMany systems of deleting ecoregions have been created. The World Wide Fund for Nature (WWF) has been active in creating one of the more recent and comprehensive systems. In this system, ecoregions are part of a nested hierarchy of ecological regions of different scales. Small units are called sites, micro-ecosystems, landtypes, and land units, among other terms. Small units are grouped into larger units called landscape mosaics, meso-ecosystems, landtype associations, and subregions, among other terms. These in turn are grouped into larger units called variously regions, ecoregions, provinces, divisions, domains, zones, ecozones, kingdoms, and so on. Hydrological regionsThe fields of hydrology and hydrography involve the study and description of water in the environment. Surface-water hydrology focuses on streams, lakes, wetlands, and other kinds of surface water (as opposed to groundwater). Hydrology is a broad field with many topics of study, including the delineation of water-based regions. There are many systems for defining surface water regions. A basic type of stream-based region is the drainage basin, or watershed. In some cases, drainage basins are directly linked to cultural and political regions. For example, the Hudson Bay drainage basin was defined politically as Rupert's Land, the historic territory of the Hudson's Bay Company. Boundaries between drainage basins, called water divides, are frequently used as political boundaries. Hydrologic UnitsThe drainage basin concept is expanded upon in hierarchical systems of hydrologic units. In the United States, an effort is being made to delineate hydrologic units in a six level hierarchy covering the entire country and adhering to a standard called the "Federal Standard for Delineation of Hydrologic Unit Boundaries". The six nested levels of hydrologic unit regions are named, from largest to smallest, regions, subregions, basins, subbasins, watersheds, and subwatersheds. The system defines 21 hydrologic unit (HU) regions in the United States, 222 HU subregions, 352 HU basins, and 2,149 HU subbasins. The delineation of 5th level watersheds and 6th level subwatersheds is not complete, but estimates predict about 22,000 watersheds and 160,000 subwatersheds in the United States. All of these HU regions are given a numeric ID and a name. An example of the names and nesting hierarchy is:
Groundwater regionsGroundwater-based regions include aquifers. While aquifers are hydrographic regions in their own right, in some cases they are closely related to social, cultural, economic and land-use regions. Examples of such aquifers include the Ogallala Aquifer, which supports a vast region of irrigated farmland in the Great Plains; the Edwards Aquifer of Central Texas; the Guaraní Aquifer of central South America, including the Triple Frontier region; and the Great Artesian Basin, which is made up of several aquifers and provides water for inland eastern Australian regions such as the Murray-Darling Basin.junaid Physiographic regionsRegions defined based on landform characteristics are called "physiographic" or "geomorphic" regions. Physiography involves the delineation and description of regions from the viewpoint of geomorphology. Geologist Nevin Fenneman defined a classic three-level hierarchical system of physiographic regions for the United States in 1946. The regions are called divisions, provinces, and sections. For example, there are 8 large physiographic divisions, such as the Canadian Shield and the Interior Plains. These are subdivided into provinces and sections. The Appalachian Highlands division, for example, contains the Valley and Ridge province, which in turn contains three sections, the Tennessee section, Middle section, and Hudson section. The Valley and Ridge province approximately corresponds to the more general region known as the Ridge-and-valley Appalachians. Palaeogeographic regionsPalaeogeography is the study of ancient geologic environments. Since the physical structures of the Earth's surface have changed over geologic time, palaeogeographers have coined various names for ancient regions that no longer exist, from very large regions such as the supercontinents Rodinia, Pangaea, and Pannotia, to relatively small regions like Beringia. Other examples include the Tethys Ocean and Ancylus Lake. Palaeogeographic continental regions that include Laurentia, Proto-Laurasia, Laurasia, Euramerica (the "Old Red Continent"), and Gondwana. Historical regions
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