Topography
Topography is a general term in
geography, derived from the
Greek "topos" (place) and "graphein" (to draw), and refers to the lie of the
land, or various other characteristics of
Physical geography in a region; this is usually expressed in terms of the
elevation,
slope, and orientation of terrain features. The understanding of these features is an integral aspect of geography, encompassing the practice of
cartography,
surveying, and
GIS. Maps are the most common communication tool for topographic information.
Relief often used to refer to the third
dimension of a
map whether in actuality (as in a "raised relief" map, or drawn, as with
contours,
hachures or
shading) or the territory it describes. Most
18th and early
19th century national surveys did not record relief across the entire area of coverage, calculating only spot elevations at survey points. The
United States Geological Survey (USGS) topographical survey maps included contour representation of relief, and so maps that show relief, especially with exact representation of elevation, came to be called
topographic maps (or "topo" maps) in the
United States, and the usage has spread internationally.
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Example of a topographic map with contour lines |
The understanding of topography is critical for a number of reasons. In terms of
environmental quality,
agriculture, and
hydrology, understanding the topography of an area enables the understanding of
watershed boundaries,
drainage characteristics,
water movement, and impacts on
water quality. Complex arrays of topographic data are used as input parameters for
hydrology transport model]s (such as the [[SWMM or
DSSAM Models) to allow prediction of river
water quality.
Understanding topography also impinges on
soil conservation, especially in agriculture.
Contour plowing is an established practice of enabling
sustainable agriculture on sloping land, and is the practice of plowing along topographic lines.
Topography is critical
militarily because it determines the ability of
armed forces to take and hold areas, and to move
troops and material into and through areas.
Topography is important in determining
weather patterns. Two areas in proximity to each other geographically may differ radically in characteristics such as
precipitation because of elevation differences or because of a "
rain shadow" effect.
Tectonic processes and
erosional processes are the determiners of topography. Tectonic processes such as
orogenies cause land to be elevated, and erosional (and
weathering) processes cause land to be worn away to lower elevations.
*
Geomorphology*
Landform*
bathymetry
