River Study Guide

Hydrologic cycle

The natural process of water circulating between Earth’s atmosphere, surface, and land.

Ex. Imagine water from a lake evaporating into the air, forming clouds, then falling as rain and flowing back into the lake. This is the water cycle.

Infiltration

The process of water entering the soil from the surface.

Ex. When it rains, some of the water soaks into the ground instead of running off the surface.

Runoff

Occurs when rainfall or melted snow cannot enter the ground resulting in flowing over the surface.

Ex. After a heavy rain, water flows across the ground and into nearby streams or rivers because the soil is too full to absorb it.

Transpiration

The evaporation of water leaving from parts of a plant like leaves, stems, and flowers. 

Ex. A plant releases water vapor from its leaves into the air.

Evapotranspiration

The process of water transferring from the land into the atmosphere.

Ex. Water evaporates from the surface of the ground and from plants, moving into the atmosphere.

Steam

Pathways for surface runoff and streamflow. 

Ex. A small river or creek where water flows across the land.

River

When rain occurs, some water soaks into the ground and collects over time causing streams and rivers to flow into the sea. 

Ex. Water from streams and rain gathers to form a river, which eventually flows into the sea.

Drainage Basin

An area of land where water from precipitation collects and flows into rivers or lakes. 

(Precipitation is condensed water in clouds falling back into Earth’s surface)

Ex. A large area of land where water from rainfall collects and drains into a river or lake.

Divide

A ridge or mountain separating drainage basins that determine the flow of the water.

Ex. A mountain that separates two areas of land where water flows in different directions, like a watershed.

Laminar Flow

The consistent movement of water in parallel layers without mixing. 

Ex. Water flows smoothly in parallel layers without mixing, like in a slow-moving stream.

Turbulent Flow

Unlike laminar flow the water moves in a chaotic and unpredictable pattern.

Ex. Water moves in a fast and chaotic way, like in a fast-flowing river with rapids.

Gradient

The change of property in water like temperature, pressure, or content within the water over a certain distance. 

Ex. A river may have a steep gradient if it flows down a mountain, or a gentle gradient if it's near the valley.

Discharge

When the volume of water changes when the ground water enters the surface body of water and enters rivers or oceans. 

Ex. The amount of water flowing into a river, which can change with rain or snowmelt.

Longitudinal Profile

The geometrical graph of elevation and distance from the stream mouth to the upper reaches. 

Ex. A map showing how the elevation of a river changes from its source to its mouth.

Abrasion

Sediments carried by water, wind, or ice grinding away surfaces causing erosion. 

Ex. Rocks carried by a river grind against the riverbed and banks, causing erosion.

Dissolved Load

Ions and dissolved materials carried within the water.

Ex. Salt dissolved in the water of a river is part of the dissolved load.

Suspended Load

Fine sediments carried into the water due to turbulence leading to flow with the water. 

Ex. Small particles like clay float in the water of a river, carried by turbulence.

Bed Load

Particles like sand or gravel are moved along the bottom side of a stream or river.

Ex. Sand and gravel that move along the bottom of a river.

Saltation

The jumping or bouncing movement of particles like sand as they are being transported through the water.

Ex. Small pebbles bounce along the riverbed, pushed by the flow of water.

Traction

Transport of large sediments like boulders along the river beds by the force of flowing water.

Ex. Large boulders are moved by the force of water flowing along the riverbed

Capacity

The maximum amount of water a specific reservoir can hold

Ex. A lake's capacity is how much water it can hold before overflowing.

Competence

The ability of systems like evaporation, condensation, and precipitation to make sure the flow of water is balanced and consistent.

Ex. The river’s ability to carry different sizes of sediment depends on how fast it flows.

Sorting

Categorizing different examples of stages within a water cycle

Ex. When a river slows down, it may deposit larger particles like pebbles first, and smaller particles like sand later.

Alluvium

Consists of sediments like sand or gravel being deposited by rivers and streams.

Ex. The sand, silt, and gravel deposited by rivers and streams.

Meander

The curvy path a river takes due to erosion and deposition along its banks.

Ex. A river takes a winding path, curving around hills or obstacles.

Cutbank

The outside bank of a meander that erodes due to faster water flow

Ex. The outside of a meander, where the faster water erodes the bank.

Point Bar

A bar formed by the deposition of sediments on the inner side of a river meander.

Ex. The inner side of a meander, where slower water deposits sand and gravel.

Oxbow Lake

Forms when a meandering river erodes through one of the necks of its meanders. 

Ex. A lake that forms when a meandering river cuts off a loop of its path.

Braided Channel

Formed when multiple shallow channels divide and merge.

Ex. A river split into several shallow channels that weave around islands of sand.

Natural Levees

Naturally formed ridges of sediment along river banks

Ex. Ridges of sediment along riverbanks that help prevent flooding.

Dendritic Drainage

A network of streams that develop in areas in uniform that does not favor any flow of water.

Ex. A river system that looks like the branches of a tree, formed in an area where water flows easily in all directions.

Radial

The movement of water from the phloem (tissue that transports food) to the xylem (tissue that transports water and minerals) in a radial direction, meaning outwards from the center of the stem.

Ex. Water and nutrients flow outward from the center of a plant stem to its leaves.

Trellis

The role of plants and/or trees within the water cycle through their transpiration process.

Ex. A pattern of streams that looks like the grid of a trellis, usually formed by folds in the earth’s surface.

Flood

Occurs when precipitation and runoff override the capacity of drainage systems.

Ex. A river overflows its banks due to too much rain or melting snow, causing water to cover the land.