Hydrologic Cycle Study Guide

Vocabulary terms and definitions covering the hydrologic cycle, above-ground and underground water processes, and groundwater characteristics.

Water cycle

The continuous movement of water between the atmosphere, land, living things, surface water, and underground.

Pool

A place where water is stored, such as oceans, lakes, glaciers, soil, groundwater, plants, and the atmosphere.

Flux

A process that moves water from one pool to another, such as evaporation, precipitation, runoff, infiltration, and groundwater flow.

Condensation

The process where water vapor cools and changes into liquid water, helping form clouds.

Evaporation

The process where liquid water changes into water vapor because of heat from the Sun.

Transpiration

The process where plants release water vapor from their leaves.

Evapotranspiration

The combined movement of water into the atmosphere through evaporation and transpiration.

Precipitation

Water that falls from clouds as rain, snow, sleet, freezing rain, or hail.

Runoff

Water from precipitation or snowmelt that flows over the land into streams, rivers, lakes, or oceans.

Snowmelt

Water produced when snow melts, which may become runoff or infiltrate the soil.

Sublimation

The process where snow or ice changes directly into water vapor without melting first.

Reservoir

A human-made lake formed when a dam blocks a river and water collects behind it.

Wetland

Land where the soil is flooded or saturated for all or part of the year, including marshes, swamps, bogs, and mangroves.

Domestic water use

Water used in homes for drinking, cooking, bathing, cleaning, flushing toilets, and watering plants.

Infiltration

The movement of water from the land's surface into the soil.

Percolation

The downward movement of water through openings in soil and rock.

Groundwater recharge

The process where infiltrated water percolates into the saturated zone and adds water to an aquifer.

Groundwater

Water stored underground in cracks and pore spaces within soil, sediment, and rock.

Aquifer

A layer of permeable rock or sediment that stores and transmits usable groundwater.

Water table

The top boundary of the saturated zone.

Saturated zone

The underground area where every available pore and crack is filled with water.

Unsaturated zone

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

Impermeable layer

A layer, such as clay or solid rock, that blocks or greatly slows water movement.

Porosity

The amount of empty space in a material that can store water.

Permeability

How easily water can move through connected spaces in a material.

Subsidence

The sinking of the land caused by removing too much groundwater, causing underground spaces to collapse.