PHS Exam 4

stream

water flowing downhill due to gravity confined to a channel

hydrologic cycle

the circulation of Earth’s water supply

precipitation

material falling to the ground because of gravity

infiltration

seeping into the ground

evaporation

process of a liquid turning into a gas

transpiration

water moving through plants

runoff

water moving across the surface

condensation

gas turning into a liquid

meandering stream

meanders through he landscape; soft material

braided stream

multiple sections confined to one channel

tributary

smaller stream that flows into a larger stream

drainage basin

land area that contributes water to a river system

drainage divide

separates drainage basins

gradient

slope that determines velocity of streamflow

discharge

volume of water flowing in the stream

dissolved load

ions dissolved in the stream; not solid

suspended load

solid particles floating in the stream

stream load

transported material

bed load

solid material in contact with the stream bed

traction

sediment that rolls along the stream bed

saltation

sediment that skips along the stream bed

competence

maximum particle size

capacity

maximum load

deposition

sediment that is not being moved

delta

sediment deposited when a stream flows into another body of water; in a fan shape; generally sand

alluvial fan

sediment deposited when a stream flows on to a flat surface; in a fan shape

natural levee

sediment. deposited as a stream overflows in its channel; form parallel to the stream channel

base level

lowest point a stream can erode to

floodplain

area adjacent to the stream that typically floods

meander

curves in the stream

cutbank

outside of bend; where erosion occurs

pointbar

inside of bend; where deposition occurs

oxbow lakes

cutoff meanders filled with water

meander scar

cutoff meander not filled with water

flood

when a stream overflows its banks

hydrograph

shows stage measurements for the gauging station

recurrence interval

the average time in years between floods of the same size

groundwater

water beneath the surface

sinkholes

dissolves by ground-water produces

caverns

caves

zone of saturation

all pores spaces in the material are filled with water

water table

the upper limit of the zone of saturation

porosity

percentage of pore spaces

permeability

ability to transmit water through connected pore spaces; the interconnectedness of pore spaces

aquifer

a permeable layer of material

aquitard

an impermeable layer of material

confined aquifer

confined between 2 aquitards; very limited area at surface to be refilled by rain events; most water in confined aquifers was put there during the last glacial period

recharge zone

area at the surface where water infiltrates the aquifer by rain events

unconfined aquifer

open to the surface that can be refilled by rain events

artesian well

water in the well rises higher than the initial groundwater level

salt intrusian

freshwater is at the top and saltwater is at the bottom

groundwater overdraft

often mildly acidic

cone of depression

pumping can form a depression due to the drawdown

subsidence

is the gradual sinking of the ground due to various factors, including the extraction of groundwater

Karst topography

terrain formed by dissolving rock at, or near, Earth’s surface

point source pollution

can tie back to a specific place

nonpoint source pollution

cannot tie back to a specific place