Geology 1121 Ch.14

What does a stream flow reflect?

plate tectonics and climate systems

What is a stream?

any body of water that flows over land in a channel

What is a river?

major branch of a stream

What is a tributary?

side channels of a stream

What are headwaters?

beginning of a stream

What is the mouth of a stream?

the end of the stream

What is discharge?

amount of water passing through a given point in a measured period of time

What is the formula for discharge?

Q=AV

What is Q in the discharge formula?

stream discharge

What is A in the discharge formula?

area of channel (L x W)

What is V in the discharge formula?

flow velocity

What is the largest river system in the world?

Amazon river (175,000 m³/sec)

What is laminar flow?

smooth water movement

What part of a channel does water move the fastest?

the center

What is turbulent flow?

rough water movement

What type of water flow is most common?

turbulent

What is an eddy?

isolated ring chape current of water

What is a whirlpool?

rapidly rotating mass of water

What is an abrasion (type of erosion)?

sand and pebbles carried by a stream erode rock along the stream channel

What is an headward erosion(type of erosion)?

upstream erosion

What are potholes (type of erosion)?

deep holes in the rock created by pebbles and cobbles that get caught in an eddy

What is scouring (type of erosion)?

removal of loose fragments from channel by rapidly moving water

What is undercutting (type of erosion)?

force of falling water splashing on nearby rocks wearing them away leaving a ledge that collapses (waterfalls)

What is suspended load(sediment transport)?

sediment grains that swirl in water w/o settling (normally sand and silt)

What is bed load(sediment transport)?

all materials carried by stream along stream bed (typically sand, pebbles, cobble)

What is dissolved load(sediment transport)?

all ions in solution from soluble minerals (gives water its taste)

What is saltation?

grains “jump” from bottom of channel into water column after hitting a rock or similar at bottom of stream

What is runoff?

all water flowing on earths surface

What is a drainage divide?

ridge that separates streams; rainfall runs down either side of the divide

What is a drainage basin?

area that funnels water into a stream

What is a permanent stream?

stream that flows all year (fed by precipitation and groundwater

What is an ephemeral stream?

stream that flows during heavy rains

Where is the groundwater table in an ephemeral stream?

below the channel

When do lakes form?

when stream flow is obstructed

What is a delta?

place of sediment deposition at mouth of river

How do you grow a delta?

add more sediment

What is a flood?

when water spills out of its channel onto the flood plain

Is flooding healthy?

flooding is indicative of a healthy river (natural occurence)

What are the characteristics of a floodplain?

composed of fine grained sediments

agricultural resource (nutrient rich)

bordered by natural levees

How do natural levees form?

water spills over existing levees and fills the floodplain leaving behind sediment at the rivers edge

What do natural levees do?

confines water to stream channel and protects against future floods

What is a flash flood?

floodwaters rise so fast that it may be impossible to escape water

What is a meandering stream?

single channel with winding and twisting snake like bends

What is a meander bend?

bend or curve in the stream

How do meandering streams/bends occur?

a stream erodes outer banks of bends and deposits sediment against the inner bank

What is a point bar?

inside bank of a stream, slower current

What is a cut bank?

outside bank of stream (erodes away)

What is an oxbow lake?

u-shaped lake formed from abandoned meander loop

What is a braided stream?

stream with many dividing and interlocking channels separated by small islands (high sediment load with high water velocity)