fluvial landscapes

natural reservoirs

glaciers, atmosphere, lakes and rivers, groundwater, biosphere

evaporation

solar radiation provides energy

precipitation

rain or snow

transpiration

evaporation from plants

runoff

water flowing over land surface

infiltration

water flowing over land surface

stream

body of running water

headwaters

upper part of stream near its source

mouth

where stream enters sea lake or larger stream

channel

long narrow depression eroded by a stream into rock or sediment

banks

sides of channel

streambed

bottom of the channel

floodplain

flat valley floor composed of sediment deposited by the stream

drainage basin

total area drained by a stream and its tributaries

tributary

small stream flowing into a larger one

divide

ridge or high ground that divides one drainage basin from another

continental divide

separates the streams that flow into the pacific from those that flow into the atlantic and gulf of mexico

dendritic drainage pattern

resembles a tree

radial drainage pattern

streams diverge outward like spokes of a wheel, happens on conical mountains

rectangular drainage pattern

tributaries have frequent 90° bends and join other streams at right angles

trellis drainage pattern

parallel streams with short tributaries meeting at right angles

stream erosion

controlled by flow velocity and stream discharge

flow velocity is controlled by

the gradient (slope), shape of channel, channel roughness, thalweg

thalweg

spot in a stream with maximum velocity

high stream velocities promote ____

erosion and transportation of coarser sediments

stream discharge

volume of water flowing past a given point in a unit of time

stream gradient

downhill slope of the stream bed, usually decreases as the stream goes down

narrow, deeper channels have ____ flow

faster

smoother channels have ____ flow because ____

slower, there is less drag

wide channels ____ flow speed

decrease

rougher channels ____ flow speed

decrease

hydraulic action

ability to pick up and move rock and sediment

solution

dissolving of rock

abrasion

grinding away of stream channel by the friction and impact of sediment load

potholes

eroded into streambed by abrasive action of sediment load

how are oxbow lakes formed

meandering streams flow faster along the outside of bends, the neck of a bend will get eroded and slowly become its own straight stream, depositing along the edges causes what was a bend to now be a horseshoe shaped oxbow lake

bed load

large or heavy particles that travel on the streambed by traction or saltation

traction

large particles that roll/drag along the bottom

saltation

medium particles bounce along the bottom

suspended load

small/light particles are suspended by turbulent flow in the stream

dissolved load

dissolved ions produced by chemical weathering of material from upstream

ways that sediment is deposited

bars (deposited in middle or along the edges of stream), floodplains (strips of land built up on sides of a channel that are covered by flooding), deltas (sediment deposited at the mouth of a river), alluvial fans (large fan or cone shaped piles of sediment at the end of a narrow mountain canyon)

flooding causes

damage, erosion, flood deposits

urban flooding

paved areas and storm sewers increase runoff by inhibiting infiltration

flash floods

sudden large volume of water for short duration because of weather

dams

trap flood waters in reservoirs upstream and gradually release over time

artificial levees

increase the rivers capacity to hold water, rapid flooding happens if water goes over levees

wise land-use planning

not building where floods frequently happen naturally

downcutting

deepening a valley by erosion of the streambed

v-shaped valleys

form from downcutting combined with mass wasting and erosion

streams cannot erode past their ____

base level

base level

sea level near the coast

stream terraces

step-like landforms found above a stream and its floodplain

what causes stream terraces

rapid uplift, drops in base level, climate changes

incised meanders

retain sinuous pattern as they cut vertically down

What stream pattern forms on a broken or fractured plane

Rectangular pattern

Stream erosion is controlled by what two factors

Flow velocity, stream discharge

What are 3 ways streams erode rocks/sediment?

Hydraulic action, solution, abrasion

What is the largest reservoir on Earth

oceans

Place where stream enters sea, lake or larger stream

mouth

Upper part of stream near its source in the mountain

headwaters

Total area drained by a stream and its tributaries

drainage basin

Drainage pattern resembling a tree

dendritic

Streams diverge outward like spokes on a wheel

radial

Parallel streams with short tributaries meeting at right angles.

Trellis

How do oxbow lakes form?

Meandering stream erodes and a meandering cutoff form and due to flooding or erosion an oxbow lake form.

Describe the three different kinds of hydraulic action.

Bed, suspended, dissolved

Ridges of sediment deposited in the middle or along the sides of a stream.

bars

Body of sediment deposited at the mouth of a river.

delta

Local sudden floods of large volume and short duration is called what?

flash flood

What controls the base level in V-shaped valleys?

Base level (sea level near coast)

What is thawleg

Location of maximum velocity in a stream.