the total land and area that drain surface water to a common point or body of water

aka river basin

the direction of exposure of sloping lands in a watershed

opposite direction of orientation

runoff water moving towards a river or stream

• usually only flows for short distance and doesn't enter stream because it percolates
• more overland flow during heavy, short downpours

when precipitation percolates just below the land surface and moves in the same direction as the overland flow

more interflow during a soaking shower

beginning of a river

aka source

temporary water storage on the banks of a river

after rainstorm, rivers rise and cause some water to percolate into the banks

shallow groundwater flow beneath the river bed

biologically active (bacteria) especially in cold waters of high altitude

broad, looping bends in a river

• erosion and higher velocity on outer bends
• deposition and slower on lower bends

Interwined channels separted by small, temporary island

• common in glacial areas
• form beds of gravel during floods and change course of river

form when a meander becomes isolated from channel

eventually dries up and becomes a meander scar

rivers in dry climates that have no continuous water source, only recharged from storm

• called "wadis" in Africa, "arroyos" in US southwest 
• smooth land prone to dangerous flash flooding

flow both after a storm and wet seasons

• seasonal and post-storm flow

loses flow from discharged water 

• discharged water percolates and feeds groundwater flow

gets base flow from groundwater and increases discharge

• river fed by groundwater

the slope or fall of a river

• gradient decreases as river moves downstream and reduces velocity

formed when glacial debris blocked the upper reaches of a mountain and filled with water

• common in Rocky Mountains

A landlocked basin that filled with water when glaciers melted

• created in dry climates and have mostly dried up

depressions created by blocks of stranded, buried glacial ice that melted 

• created where depression is deep enough to reach groundwater

lake bottom where organic material has sunk/drifted to

• home to bacteria, mollusks, and algae

warm, active area of surface water mixing, high concentration of oxygen, and abundant animal and plant life

• forms above cool layer (hypolimnion)

cold, dark, still water layer

• formed under warm layer (hypolimnion)

when cooler air chills the surface water and it sinks to bottom, replacing the now warmer water from the bottom of the lake 

• occurs only in midlatitudes
• important for nutrient and oxygen cycling

difference in water level elevation in a lake

• water levels oscillate due to wind or sudden atmospheric pressure changes

graph meausres discharge vs. stage

•  measures reservoir storage
• eliminates need for velocity and depth measurements

height of water surface above a a set reference elevation

• measured with staff gage

volume of water flowing past a given point during a given time

• measured in cubic feet/meters per second
• (cross secion area of channel)  x  (average water velocity)

Q = AV

(cross section area) x (average water velocity)

• velocity measured with flow meter

1 in 100 chance of flooding each year 

• probability flood event will occur each year

maximum depth (amount) of precipitation that is possible during a storm

• finite limit for precipitation from storm

maximum surface water flow in drainage area expected from probable maximum precipitation event

• dams must be built to hold 100% PMF without flooding

created when a river deposits material on the land surface, generally at the base of a mountain valley

• susceptible to mudslides