Topographic maps are specialized maps that show topography in terms of elevation above sea level.
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.
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 materiel into and through areas.
Topography is important in determining weather patterns. Two areas in fairly close proximity geographically may differ radically in characteristics such as rainfall 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. Either process may determine steep slopes, etc.
See also: geomorphology, landform.