• source
    In the 1930s, the Civilian Conservation Corps (CCC) modified the channel of the Mississippi as it emerges from Lake Itasca.

    Photograph by Ryan Hanson, MyShot

    Get to the Source
    Finding the source of the Nile River was a major exploration goal in the 19th century. The Nile has two major tributaries, the White Nile and the Blue Nile. The Blue Nile's source is Lake Tana, Ethiopia.

    The source of the White Nile is more difficult to find. Lake Victoria is often cited as the source, but Lake Victoria has many tributaries. The furthest documented tributary to Lake Victoria, and therefore the White Nile, is the high-altitude rain forest in Nyungwe Forest, Rwanda.

    The place where a river begins is called its source. River sources are also called headwaters.

    Rivers often get their water from many tributaries, or smaller streams, that join together. The tributary that started the farthest distance from the river's end would be considered the source, or headwaters.

    Many rivers, including the Rhone in Western Europe, begin as streams in mountains or hills. As ice and snow melt, streams begin to flow downward from high mountains and the bases of glaciers.

    When a glacier is a river's source, the river has glacial headwaters. The Ganges River has glacial headwaters. The source of the Ganges, in India and Bangladesh, is the Gangotri Glacier in the Himalayas of northern India.

    Springs are the sources of some rivers. A spring is a place where water in the Earth, called groundwater, flows to the surface naturally. A spring forms when an aquifer, or natural underground reservoir, fills with groundwater and overflows. The spring of the Breg River, in Germany's Black Forest, is the source of the Danube.

    Lakes with outflowing streams can become the headwaters of rivers, but only if they do not have streams that flow into them. (The inflowing stream—not the lake—would be a source of the river.) The Mississippi River, the largest river in North America, starts as a stream from Lake Itasca, a glacial lake in the U.S. state of Minnesota.

  • Term Part of Speech Definition Encyclopedic Entry
    aquifer Noun

    an underground layer of rock or earth which holds groundwater.

    Encyclopedic Entry: aquifer
    exploration Noun

    study and investigation of unknown places.

    glacial headwaters Noun

    river's source that comes from glacial runoff.

    glacial lake Noun

    body of water created by a melting glacier.

    glacier Noun

    mass of ice that moves slowly over land.

    Encyclopedic Entry: glacier
    groundwater Noun

    water found in an aquifer.

    Encyclopedic Entry: groundwater
    headwater Noun

    source of a river.

    hill Noun

    land that rises above its surroundings and has a rounded summit, usually less than 300 meters (1,000 feet).

    Encyclopedic Entry: hill
    ice Noun

    water in its solid form.

    Encyclopedic Entry: ice
    lake Noun

    body of water surrounded by land.

    mountain Noun

    landmass that forms as tectonic plates interact with each other.

    rain forest Noun

    area of tall evergreen trees and a high amount of rainfall.

    reservoir Noun

    natural or man-made lake where water is stored.

    Encyclopedic Entry: reservoir
    river Noun

    large stream of flowing fresh water.

    Encyclopedic Entry: river
    snow Noun

    precipitation made of ice crystals.

    source Noun

    beginning of a stream, river, or other flow of water.

    Encyclopedic Entry: source
    spring Noun

    small flow of water flowing naturally from an underground water source.

    stream Noun

    body of flowing water.

    Encyclopedic Entry: stream
    tributary Noun

    stream that feeds, or flows, into a larger stream.

    Encyclopedic Entry: tributary
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