channelThe trough that a stream has cut and now flows in. The flow of the stream itself shapes the channel. On a floodplain a channel slowly shifts from side to side.
confluenceThe place where two streams join into one channel. The Ohio River begins at the confluence of the Allegheny and Monongahela rivers.
currentThe onward push of a river's moving water. Its speed depends on how much water is flowing, how steep the channel is and what shape it has.
downstreamIn the direction the water flows, toward the mouth. Over time the bends of a river migrate downstream.
mouthA river's end, where it empties into larger water. The current slows at the mouth, so the river drops much of the sediment it was carrying there.
riverThe main watercourse that drains a valley. A river may run dry before it reaches its end, or flow only in certain seasons.
riverbankThe rising ground at either side of a channel. The left bank and the right bank of a river are named as seen by someone looking the way the water flows.
Show all 36 terms (29 more)
Parts of a river, continued
riverbedThe floor of a channel, under the water. A bed usually has no land plants growing on it, only water plants.
sourceThe spot where a river's flow first begins. It is also called the headwaters. The traditional source of the Mississippi is Lake Itasca in Minnesota.
tributaryA side stream that gives its water to the main river. A tributary does not flow straight into a sea or ocean. The two great tributaries of the Nile are named the Blue and the White.
upstreamToward the source, against the current. A river's length can be measured from its mouth to its most distant headwater, the point farthest upstream.
watershedThe whole area of land whose water feeds one river. Drainage basin is another name for it. The watershed of the Mississippi is the largest in the United States.
Landforms a river makes 12
braided riverA river of many channels that split and rejoin. The channels part and rejoin around bars of sediment, called braid bars, that often do not last. Braided rivers tend to carry heavy loads of sediment.
cut bankThe steep outer bank of a bend, worn by the current. It is also called a river cliff. The stream strikes this bank and keeps eroding it.
deltaNew land a river builds from sediment at its mouth. The name comes from the triangle shape of the Greek capital letter delta. Deltas are major farming regions.
distributaryA branch that splits away from the main river. A distributary carries water away from the main channel, where a tributary brings it in. Distributaries are common on deltas, where a river divides as it nears a lake or an ocean.
floodplainBottomland laid down by a river's own overflows. Floods leave clay, silt and sand behind, so floodplain soil is often fertile and good for farming.
leveeAn embankment that keeps a river inside its channel. Natural levees build up as floodwater drops sediment on the banks. People build levees to protect the land beside a river from flooding.
meanderOne of a river's regular snaking curves. The river wears away the outside of each bend and builds up the inside, so its meanders shift over time. The word comes from the winding Menderes River of Asia Minor.
oxbow lakeA curved lake that was once a bend of the river. It is named for the U-shaped collar of an ox's harness. In Australia an oxbow lake is called a billabong.
plunge poolThe deep basin scoured out at a waterfall's foot. The force of the falling water on the rock below carves it out.
point barA bank of sand and gravel built up inside a bend. It is crescent-shaped and slopes gently into the water.
rapidsA reach where a river turns shallow and turbulent. The riverbed is steeper there, so the water speeds up, and rocks may show above the surface.
waterfallA point where a stream pours over a steep drop. Most form where a river runs over hard rock onto softer rock that wears away faster. Angel Falls in Venezuela, 979 meters high, is the tallest uninterrupted waterfall in the world.
How a river works 12
alluviumThe loose material that a river has laid down. It can be clay, silt, sand or gravel, and it has not hardened into rock. Floodplain alluvium can be very fertile.
base levelThe level below which a river cannot erode its bed. For a river that reaches the ocean, sea level is the final base level. John Wesley Powell introduced the term in 1875.
damA structure that blocks a river and holds its flow. Some dams are massive walls of concrete or masonry. Others are great banks of earth and rock.
depositionThe settling of carried material as a flow weakens. Deltas, point bars and floodplains are all built by deposition.
dischargeHow much water flows past a point each second. It equals the speed of the water times the area of the channel's cross-section. The Amazon has the greatest discharge of any river.
erosionA river's wearing down of the land it crosses. A river erodes its bed and its banks. Erosion is not the same as weathering, which involves no movement.
floodA river risen so high that it leaves its channel. A flash flood is one that begins less than six hours after the rain that causes it.
gradientHow steeply a river drops along its course. It is measured as the drop in elevation over a horizontal distance, often in meters per kilometer or feet per mile.
intermittent streamA stream that stops flowing for part of each year. Such streams drain large arid and semi-arid regions. A stream that flows all year round is called perennial.
reservoirA man-made lake that fills a dammed valley. Many reservoirs are also used to generate electricity.
sedimentGrains of every size, clay to boulder, moved by water. Fast water moves more sediment, and larger pieces of it, than slow water. That is why rivers look muddier during storms.
stream gaugeA station that records a river's level and flow. The height of the water at a gauge is called the stage. The United States Geological Survey runs thousands of gauges across the country.
This rivers vocabulary worksheet lists river, source, mouth, tributary, confluence, channel, riverbed, riverbank, current, upstream, downstream and watershed down the left, with their meanings in another order down the right. An answer key prints as the last page.
Read the full guide
Landforms a river makes
Set opens on Parts of a river. The second set has meander, cut bank, point bar, oxbow lake, floodplain, levee, delta, distributary, rapids, waterfall, plunge pool and braided river.
How a river works
The third set has erosion, deposition, sediment, alluvium, discharge, gradient, base level, flood, stream gauge, dam, reservoir and intermittent stream.
Canyon, gorge, sandbar and alluvial fan are on the weathering and erosion word search.
Questions and answers
What is the longest river in the world?
The Nile is usually named: about 4,130 miles (6,650 kilometers) long. The Amazon, at about 4,000 miles, is a close second, and some measurements make it the longer of the two.
What is the difference between a river and a stream?
Size, and there is no fixed line. Stream is the general word for water flowing in a channel. A long, large stream is usually called a river, and a smaller one a creek.
How is an oxbow lake formed?
The bends of a meandering river grow more curved until the river cuts through the narrow neck of one of them and takes the shorter course. The ends of the abandoned loop then silt up, leaving a lake.
What are the three courses of a river?
The upper, middle and lower course. In the upper course the river is small and cuts downward, making waterfalls and V-shaped valleys. Tributaries swell it in the middle course, and in the lower course it is wide and deep.