Triple Divide Points and North American Drainage Basins

Glossary

Abelian - An Abelian group is a group whose group operation commutes, that is   for every pair of elements in the group.  A Group is a set together with a binary operation that assigns to every pair of elements of the group a unique element of the group. The binary operation must satisfy three conditions.

1.   for every three elements of the group and where + is the group operation.

2.  There is an element, e,  of the group where    for every element a of the group.  e is called the identity.

3. For every element a of the group there is an element,, where .

An example of a group is the integers, {… -2,-1, 0, 1, 2,  …}, the group operation is addition and the identity is 0.

Continental Divide - The Continental Divide, also called the Great Divide, is a natural boundary line separating waters that flow into the Atlantic Ocean or Gulf of Mexico from those that flow into the Pacific Ocean. It runs north-south from Alaska to northwestern South America. In the conterminous United States, it follows the crest of the Rocky Mountains.

Confluence - (1) The act of flowing together; the meeting or junction of two or more streams or rivers; also, the place where these streams meet. (2) The stream or body of water formed by the junction of two or more streams or rivers; a combined flood.

Drainage Basin - Part of the surface of the earth that is occupied by a drainage system, which consists of a surface stream or water body together with all tributary surface streams and water bodies. The term is used synonymously with watershed, river basin, or catchment.

Euclidian Metric Topology – The Euclidean Metric is a method for computing the distance between two points in the plane where the distance is computed by the formula   .  Where the two points are given by the coordinates    and .  The Euclidean Metric Topology is the topology that is generated by this metric.

Evaporation - Evaporation can be defined as the process by which liquid water is converted into a gaseous state. Evaporation can only occur when water is available. It also requires that the humidity of the atmosphere be less than the evaporating surface (at 100 % relative humidity there is no more evaporation). The evaporation process requires large amounts of energy. For example, the evaporation of one gram of water at a temperature of 100° Celsius requires 540 calories of heat energy (600 calories at 0° Celsius).

GIS - Geographic Information System, A geographic information system merges information in a computer database with spatial coordinates on a digital map.

Hydrology -Field of physical geography that studies the hydrosphere.

Hydrosphere - The hydrosphere describes the waters of the Earth. Water exists on the Earth in various stores, including the: atmosphere, oceans, lakes, rivers, glaciers, snowfields and groundwater. Water moves from one store to another by way of: evaporation, condensation, precipitation, deposition, runoff, infiltration, sublimation, transpiration, and groundwater flow.

Modulo - We say that two numbers n and m are equivalent modulo another number x if   for some integer k.   As an example if x were 400 meters then starting at the start/finish line of a 400 meter track two distance run would be equivalent modulo 400 if they both ended at the same point on the track regardless of the number of laps run.

Percolation - Vertical movement or infiltration of water from the Earth's surface to its subsurface. Movement usually stops when the flowing water reaches the water table.

Precipitation -(1) Is any aqueous deposit, in liquid or solid form, that develops in a saturated atmosphere (relative humidity equals 100 %) and falls to the ground generally from clouds. Most clouds, however, do not produce precipitation. In many clouds, water droplets and ice crystals are too small to overcome natural updrafts found in the atmosphere. As a result, the tiny water droplets and ice crystals remain suspended in the atmosphere as clouds. (2) The state of being precipitated from a solution.

Topography -The relief exhibited by a surface.

Topology - The description of how spatial features are connected to each other.

Tributary - (1) A stream which joins another stream or body of water. (2) A stream or other body of water, surface or underground, which contributes its water, even though intermittently and in small quantities, to another and larger stream or body of water.

Citation: Pidwirny, M. (2006). Fundamentals of Physical Geography, 2nd Edition. November 27th, 2006. http://www.physicalgeography.net/fundamentals/contents.html