Chapter 14 Rivers & Streams

stream

a ribbon of water that flows in a channel

trough

a trough dug into the ground surface by flowing water

headwaters

the beginning point of a stream

mouth

The outlet of a stream where it discharges into another stream, a lake, or a sea.

flood

an event during which the volume of water in a stream becomes so great that it covers areas outside the stream’s normal channels

sheetwash

a film of water less than a few mm thick that covers the ground surface during heavy rains

runoff

when excess rainwater, stormwater, meltwater, or other sources can no longer sufficiently rapidly infiltrate the soil

downcutting

extra water flow erodes and deepens the river channel

headward erosion

the process by which a stream channel lengthens up its slope as the flow of water increases

tributaries

a smaller stream that flows into a larger stream

drainage network

an array of interconnecting streams that together drain an area

dendritic

fairly uniform substrate

trellis

landscape of parallel ridges and valleys

radical

cone-shaped mountain

parallel

steep uniform slope

rectangular

rectangular grid of fractures (joints), breaking up the ground

watershed

the region that collects water that feeds into a given drainage network

drainage divide

a ridge that separates one watershed from another

permanent streams

stream that flows year-round

Permanent streams exist bc

lies below the water table or because more water is supplied from upstream than can infiltrate the ground

ephemeral streams

flowing water for only part of the year bc stream bed exists below water table or meltwater exceeds the rate at which it infiltrates the ground

uplift

the upward movement of earth’s surface

subsidence

the sinking movement of earth’s surface

relief

the difference in elevation between adjacent high and low regions on the land surface

downslope movement

The tumbling or sliding of rock and sediment from higher elevations to lower ones.

discharge

volume of water in a conduit

conduit

channel of water

hydrologic water cycle

Evaporation > Transpiration > Sublimation > Condensation > Transportation > Precipitation > Deposition > Infiltration > Runoff > Groundwater flow

evaporation

Liquid water heats up and turns into water vapor

transpiration

Plants release water vapor from their leaves

sublimation

Solid ice changes directly into water vapor

condensation

Water vapor cools and turns into liquid droplets

transportation

Wind moves water vapor or clouds

precipitation

Water falls to Earth as rain, snow, sleet, or hail.

deposition

Water vapor turns directly into solid ice

infilitration

Water soaks down into the soil

runoff

Water flows over land into streams, rivers, and lakes

groundwater flow

Water moves underground through rock and soil

relative humidity

(amount of water vapor in air)/
(amount of water vapor air can hold)

rain shadow

area of significantly reduced rainfall behind a mountainous region

vadose zone

unsaturated zone above the water table, containing both air and water

hydraulic gradient

difference in the hydraulic head over a distance

hydraulic head

level of water in a well, measuring energy at a point

darcy’s law

flow of a fluid through a porous medium