GEOL 100 - Streams and Floods

Formation of a v-shaped valley

-River is cut down my vertical erosion (hydraulic action and abrasion) -Mass movement of material slides down the valley

Pothole

A depression formed in a stream channel by the abrasive action of the water's sediment load.

radial drainage

A flow pattern where streams flow outward and downward from a central elevated point.

badlands topography

A landscape with steeper slopes, sparse vegetation, thin soils, and extensive stream network.

Permanent stream

A stream that flows year-round because its bed lies below the water table, or because more water is supplied from upstream than can infiltrate the ground

Formation of a U-shaped valley

A v-shaped valley fills with glacial ice. The glacier widens, deepens and straightens the valley through abrasion and plucking. Interlocking spurs are cut off to create truncated spurs.

ephemeral streams flow _____ the water table and exist in ____ climates

Above, arid

Meanders form only in ____ plains

Alluvial/flat

Watershed

An ecosystem where all water runoff drains into a single body of water

dendritic drainage

An irregular stream drainage network that resembles the limbs of a branching tree.

Radial drainage form around _____

Cone-like mountains

_____ separates drainage into one once an from drainage into another ocean

Continental divide

Amazon watershed has a _____ drainage network

Dendritic

Formation of stair-step canyon

Downcutting through alternating hard and soft strata

rectangular drainage

Drainage along joints and develops a grid or vertical joints

Erosion by running water

During flood stage, rivers can move massive amounts of sediment.

Canyon

Formed by linkage of potholes

Swampy inland delta

Forms where river reaches a closed drainage basin where all water evaporate and never reaches any lake or ocean

Dendritic drainage networks have _____ and _____

Gentle slopes, substrate uniform

Water with ____ results in a strong erosional force

High sediment load

Stream down cuts and produces new alluvial plain due to _____ or _____

Increase in discharge, lowering of base level

Amazon watershed

Largest drainage basin in the world and discharges 200,000 m^3 / second

headward erosion

Lengthening of the stream

The river flows the fastest in ____ because there is ______ between substrate and banks

Middle of river, friction

Velocity highest at outer edge leads to

Outer bank erodes faster

If streambed is curved, water flows fastest on _____ of curve

Outside

Badlands topography is caused by

Parallel drainage

Valley shapes

River (v) and glacier (u)

Meanders form when ______

Running water travels over a plain that has a very gentle slope

Majority of water on earth is _____

Salt water

Sediment is transported through _____ and _____

Saltation, rolling

Velocity lowest at inner edge leads to

Sediment depositing there, forming point bars

Turbulence flow develops because of ____ of one water volume against its neighbor

Shearing

The greater that the wetted perimeter is, the ____ the flow

Slower

Flow in hyporheic zone is ____ than in stream bed due to ______ in the hyporheic zone

Slower, friction

In a curved stream, water flow in middle of river is _____

Slowest

Meandering Streams

Streams that have channels with many curves

Permanent streams rely on ___, ____, and _____

Temperature, tropical climates, elevation with respect to water table

Flow velocity

The distance the fluid travels through a system in a given period of time.

suspended load

The load contains small rocks and soil in suspension, which can make the river look muddy.

Saltation

The movement of sand or other sediments by short jumps and bounces that is caused by wind or water

hyporheic zone

The portion of the substrate below and adjacent to a stream bed where water movement still occurs, either from the stream or from groundwater moving into the stream.

When ocean currents are strong, deltas have a ___ shape

Triangular

Shape of stream evolves due to ____ and ____

Variation in water depth, associated friction

Erosion efficiency depends on ____, ___, and ____

Velocity of water, volume of water, sediment load, gradient of water

Dissolution

Water dissolved soluble minerals and carries the resulting ions away

Bird's foot delta

When ocean currents are weak compared to river current and mini deltas are formed out of bigger deltas

Abrasion

When water is loaded with sediment, it acts like sandpaper, grinding of channel bed and walls

deposition of point bar

__ _ ___ ___ occurs on the *inside of a bend* to produce a point bar; low velocity

Point bars

a crescent-shaped accumulation of sand and gravel deposited on the inside of a meander

sheetwash

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

Bedload

a load of coarse sediment, mostly coarse silt and sand, that moves along a riverbed (bottom) due to the flowing of water, in contrast to being carried in suspension

terrace

a raised, flat mound of earth (dirt) that looks like a platform with sloping sides

parallel drainage

associated with steep slopes

trellis drainage

drainage pattern in which most of the streams occupy parallel ridges and valleys, pattern usually develops on folded strata of rocks with differing resistance to erosion

Formation of deltas

found at the mouth of large rivers. They are formed by deposition. > When a river reaches another body of water, such as an ocean, it loses velocity and deposits sediment. > If the river deposits sediment faster than coastal processes erode it, sediment builds up in layers in a fan-shape. > As the river is now flowing slowly over an almost flat gradient, the channel fills up and the river splits into many smaller channels called distributaries and creates large areas of wetlands.

Ephemeral streams

have flowing water either episodically or during a portion of the year

Drainage divides

highland or ridge that separates one drainage basin from another

Whirlpools can be created in some restricted shallow passages due to ________.

reversing tidal currents/eddies

eddy

swirling current of water caused by friction along banks

drainage basin

the area from which a single stream or river and its tributaries drains all of the water

cut bank

the area of active erosion on the outside of a meander/stream

hydrologic cycle

the movement of water through the biosphere

Trunk stream

the primary stream of a drainage basin

downcutting

the process in which water flowing through a channel cuts into the substrate and eroded the substrate relative to its surroundings

Alluvium

the sorted fluvial material deposited by a stream