All rivers are parts of a larger system called a watershed, where a river and its branches drain land. Rivers are better defined as large, natural streams flowing through channels draining into even larger water bodies. All rivers are different, but they are comprised of common parts. River system parts include the river source, river mouth, downstream, upstream, flood plain, main-river, meander, tributary, watershed boundary, and wetlands.
A river’s source is the beginning of the stream. Sometimes this area is called headwaters. Often, this source is located in mountains, from glacial melt, a ground spring, or run off caused by melting snow or rain. The place where the river runs into a larger body of water such as a lake, the ocean, or another river is referred to as the river’s mouth.
When the stream runs in a direction near the river’s mouth it is called a downstream. However, the river may run in a direction closer to its source that is then considered upstream.
A flood plain, when developed entirely, is flat land on either side that, during times of high precipitation, may flood. Often its soil is nutrient rich because of the deposits that run through rivers. The river runs through channels and through its course there is one primary channel. This channel is the main-river.
Frequently, there are loops in river channels. Such channels are called meanders. Just as the name implies meandering rivers run back and forth not straight down stream. Tributaries are small streams that connect to the main river or another stream.
Tributaries drain tracts of land called watersheds. Watershed boundaries mark the furthest channels of watersheds, or drainage divides. Negative human interaction may impact a watershed’s boundaries. When this occurs havoc may take place within other river system parts, such as tributaries and the river mouth. Human interaction greatly affect river quality.
Wetlands assist with river quality maintenance. They filter pollutants out while exchanging sediment and regulating nutrient flow. Wetlands are saturated low-lying pieces of land. Often wetlands house vegetation adapted to wet environments.
Major river systems share certain characteristics. Sloping landscapes with concentrated rainfall yields the largest rivers. Major river systems exist on most continents. Inner drainage inhibits dry to semi-arid areas such as deserts from having great river systems. This is the same as polar regions, which tend to expand their glaciers with any drainage.
Often humid areas with a lot of limestone deposits prevent major river systems from forming. Poor drainage occurs because of the pores in limestone. A delta is a big deposit of sediment at a river’s mouth. Each of the parts of a river connects to form a self-replenishing system.