Hydrologic Cycle, Groundwater, and Geologic Features

Hydrologic Cycle

The continuous movement of water on, above, and below the surface of the Earth.

Hydrology

The study of the movement, distribution, and quality of water on Earth.

Reservoirs

Natural or artificial lakes used to store water.

Fluxes

The rates of flow of water between different components of the hydrologic cycle.

Infiltration

The process by which water enters the soil from the surface.

Runoff

Water that flows over the ground surface to streams and rivers.

Evaporation

The process by which water changes from a liquid to a gas.

Precipitation

Any form of water that falls from the atmosphere to the Earth's surface.

Transpiration

The process by which water is absorbed by plants and released as vapor.

Groundwater

Water that is stored underground in soil and rock formations.

Ultimate base level

The lowest point to which a river can erode.

Stream head

The source or beginning of a stream.

Stream mouth

The point where a stream flows into a larger body of water.

Channel

The physical confine of a river or stream.

Banks

The sides of a river or stream channel.

Drainage basin

The area of land where all the water drains to a common outlet.

Stream load

The materials carried by a stream, including bed load, suspended load, and dissolved load.

Bed load

The portion of a stream's load that is carried along the bottom.

Suspended load

The particles that are carried in the water column of a stream.

Dissolved load

The minerals and nutrients that are dissolved in the water of a stream.

Intermittent stream

A stream that does not flow continuously, drying up at certain times of the year.

Downcutting

The process by which a river erodes its channel downward.

'V'-shaped valleys

Valleys formed by the downcutting of rivers, characterized by a V shape.

Perennial river

A river that flows continuously throughout the year.

'U'-shaped valleys

Valleys formed by glacial erosion, characterized by a U shape.

Sidecutting

The process by which a river erodes its banks, widening the valley.

Meander

A curve or bend in a river.

Floodplain

The flat area surrounding a river that is subject to flooding.

Lowland river

A river that flows through flat or gently rolling terrain.

Upland stream

A stream that flows through hilly or mountainous terrain.

Point bar

A deposit of sediment on the inside bend of a river.

Cutbank

The eroded bank on the outside bend of a river.

Oxbow lake

A crescent-shaped lake formed when a meander is cut off from the river.

Back swamp

A low-lying area adjacent to a river that is often flooded.

Water table

The upper surface of the saturated zone in the ground.

Perched water table

A localized zone of saturation above the main water table.

Spring

A natural flow of groundwater to the surface.

Saturated zone

The area of soil or rock where all the pores are filled with water.

Unsaturated zone

The area above the water table where the pores contain both air and water.

Permeability

The ability of a material to transmit water.

Porosity

The percentage of a material's volume that is made up of pores.

Artesian wells

Wells that tap into confined aquifers, allowing water to flow to the surface under pressure.

Aquifer

A geological formation that can store and transmit water.

Aquitard

A layer of material that restricts the flow of groundwater.

Confined aquifer

An aquifer that is trapped between impermeable layers.

Unconfined aquifer

An aquifer that is open to the surface and can recharge freely.

Recharge area

The area where water infiltrates to replenish an aquifer.

Karst topography

A landscape formed by the dissolution of soluble rocks, often featuring sinkholes and caves.

Limestone

A sedimentary rock composed mainly of calcium carbonate.

Sinkhole

A depression or hole in the ground caused by the collapse of a surface layer.

Sinkhole lake

A lake that forms in a sinkhole.

Cave

A natural underground space large enough for a human to enter.

Dripstone

Mineral deposits formed by dripping water in caves.

Stalactite

A mineral formation that hangs from the ceiling of a cave.

Stalagmite

A mineral formation that rises from the floor of a cave.

Crest

The highest point of a wave.

Trough

The lowest point between two waves.

Wavelength

The distance between successive crests or troughs of a wave.

Wave base

The depth at which the wave energy dissipates.

Wave break

The point at which a wave becomes too steep and collapses.

Surf

The area where waves break and create foam.

Wave refraction

The bending of waves as they approach the shore.

Headland

A coastal landform that juts out into the sea.

Bay

A body of water partially enclosed by land.

Longshore currents

Water currents that move parallel to the shore.

Beach drift

The movement of sand along the beach by wave action.

Beach

A landform along the shoreline of an ocean or lake.

Spit

A narrow point of land extending into a body of water.

Baymouth bar

A sandbar that closes off a bay from the open ocean.

Daily tides

The regular rise and fall of sea level caused by the gravitational pull of the moon and sun.

High tide

The maximum level of the sea reached at high tide.

Low tide

The minimum level of the sea reached at low tide.

Monthly tides

Tidal variations that occur over a month due to the moon's phases.

Spring tide

The highest tides that occur when the sun, moon, and Earth are aligned.

Neap tide

The lowest tides that occur when the sun and moon are at right angles.

Lunar phases

The different stages of the moon's cycle as it orbits Earth.

Desert

A dry, barren area with little precipitation.

Subtropical desert

A desert located in the subtropics characterized by high temperatures and low rainfall.

Rain shadow desert

A desert that forms on the leeward side of a mountain range due to reduced rainfall.

Polar desert

A desert located in polar regions characterized by extremely low temperatures.

Steppe

A large area of flat unforested grassland.

Loess

A fine-grained sediment deposited by wind.

Sand dunes

Mounds of sand formed by wind action.

Pedestal rock

A rock formation that is wider at the top than at the bottom.

Ventifacts

Rocks that have been shaped by wind erosion.

Alluvial fan

A fan-shaped deposit of sediment formed where a river flows out of a mountain.

Bajada

A broad slope of sediment formed by the coalescence of alluvial fans.

Playa lake

A temporary lake that forms in a desert.

Inselbergs

Isolated hills or mountains rising abruptly from a plain.

Pediment

A gently sloping bedrock surface at the base of a mountain.

Desert deflation

The removal of loose, fine-grained particles from the desert surface by wind.

Glacier

A large mass of ice that moves slowly over land.

Valley glacier

A glacier that forms in a valley and flows down the valley.

Ice Caps

Thick layers of ice that cover large areas of land.

Cirque

A bowl-shaped depression formed by glacial erosion.

Zone of accumulation

The area of a glacier where snow and ice accumulate.

Snow line

The elevation above which snow remains year-round.

Zone of ablation

The area of a glacier where ice melts and is lost.

Plastic flow

The movement of ice within a glacier due to pressure.

Glacial surge

A rapid movement of a glacier.