geo - rivers

erosion

The constant flowing of a river wearing away and removing material from its channel (the river bed and banks).

ways water can be stored

gas, liquid, solid

vapor, water, ice

erosion

The constant flowing of a river wearing away and removing material from its channel (the river bed and banks).

ways water can be stored

gas, liquid, solid

vapor, water, ice

directions of erosion (2)

lateral, vertical

types of erosion (4) - HAAS

• HAAS

• hydraulic action

• abrasion

• attrition

• solution

discharge

amount of water within a river during a specific amount of time

transportation

movement of material via a process

4 types of transportation

3s 1t

• traction

• suspension

• saltation

• solution

drainage basin

an area which water resulted from precipitation is collected and drained out through an outlet

watershed

the boundary between drainage basins

tributary

a smaller sized river becoming apart of/ joining a larger river

confluence

the point which two rivers meet/ join together

river source

the starting point of the river

river mouth

the point where a river flows into a larger body of water eg sea/ ocean

hydrological cycle

The processes by which water moves through the landscape / water cycle

what are drainage basins divided by?

watershed

evaporation

The change of water from a liquid to a gas (water vapour) due to heat from the sun

liquid → gas

Condensation

When water cools and changes from water vapour into a liquid (water droplets), forming clouds

gas → liquid

transpiration

process by which plants release water vapor from leaves

Evapotranspiration

The combined transfer of water vapour from the Earth's surface and plants

Precipitation

the process of water falling onto earths surface

provide examples of precipitation

• rain

• snow

• hail

• sleet (partly melted snow)

Overland flow

water moving across the surface of the earth

Infiltration

movement of water from surface into the soil

Stem flow/drip flow

Movement of water from vegetation to the ground surface.

Channel Flow

Movement of water confined within a river or stream.

water table

the level below the Earth's surface where the ground becomes wet

what kind of system is the hydrological cycle

closed system

closed system

a system of processes where there is no inputs or outputs - means water cycles continously/ repeatedly

purpose of erosion

makes river channel deeper/ wider

load

material being transported by river

stuff inside the river that is moved by the water

deposition

the removal of the river’s load due to insufficient energy to carry it for longer durations

river dumping load away into river bed cuz it dont got enough energy

what objects/ sediment are deposited first and last by a river?

first - largest and heaviest objects within load (eg boulder)

last - small and lightiest objects within load (silt, mud)

3 courses of a river

upper, middle, lower

which course do you find the most features?

middle

in which course does the river start?

upper

in which course does the river end/ where the mouth is?

lower

mouth is where the river meets the sea

where does vertical erosion occur

upper course

which course does lateral erosion occur in

lower course

velocity

speed that river is flowing at

sediment

material deposited by river

forms of river channel (3)

• striaght

• braided

• meandering

define meandering

when a river flows in broad bends.​

define straight

when river flows with few curves

define braided

The river is made up of smaller channels created by material that has been deposited.​

looks like a braid

characteristics and features of the upper course

• narrower, shallow channel

• v shaped/ steep valleys

• high bedload

• steep gradient

• waterfall

• gorges

• vshaped valley

• interlocking spurs

• potholes

• rapids

characteristics and features of middle course

• moderate gradient (not too steep but not to flat)

• wide and deep channel

• meanders

• more volume/discharge

  • increased biodiversity/life

• development of floodplains

• slip off slopes

• river cliffs

characteristics/features of lower course

• very wide and very deep channel

• floodplains

  • flat and wide

• ox bow lakes

• levees

rapids

sections of a river where the river bed has a relatively steep gradient

• located in uppercourse

• Form at places where the water is shallow and the river bed is rocky and irregular.​

• Gradient here is often steeper than at other points on the river’s course.​

• They can be caused by a band, or bands of hard rock in the river bed.​

explain the formation of a waterfall

The river flows over bands of less resistant (softer) and resistant (harder) rocks. The less resistant rock is more quickly worn away due to differential erosion. The river erodes the rocks in three main ways:

- Hydraulic action – when the sheer force of the water gets into small cracks and breaks down the rock.

- Corrasion – when the river bed and banks are eroded by the load hitting against them.

- Corrosion – when the river water dissolves minerals from the rocks and washes them away.

The river undercuts the harder rock leaving an overhang which becomes unsupported and collapses into the plunge pool below. After the overhang falls, some of the rocks are swirled around by the river and this helps to form a deep plunge pool below the waterfall. The plunge pool is also deepened during times of high discharge when hydraulic action is most powerful. The waterfall is moved upstream, the process continues, and a steep-sided gorge is cut back into the hillside.

-
Hard rock overlies softer rock / (passes over) hard then soft / alternating

hard and soft;

Hard rock resists erosion / softer rock is eroded rapidly;

Undercutting / overhang develops;

Overhang collapses;

Retreat of waterfall / process repeats;

Specific named methods of erosion or description of (1 MAX)

floodplain

dry land beside river

Floodplains form due to both erosion and deposition.​

During a flood, the load is deposited (as the river loses its speed and energy to transport material)​

Over time, the height of the floodplain increases as material is deposited with each flood​

Floodplains are very fertile because its made up of alluvium (deposited silt from a river flood). ​

The floodplain is often a wide, flat area caused by meanders shifting along the valley​

levee

Formed by deposition when the river floods​

The river’s load is made of different sized particles - the heaviest is depositied first when the river floods​

The larger particles, often pebble-sized, form the leveés.​

Levees are raised banks right next to the river banks.​

As the water continues to flood further away from the river banks, the sands are deposited next, then the smaller silt ​

This build up of sand and silt leads to the formation of a flat piece of land (floodplain) either side of the river - just after the levees​

Delta

a delta is formed when the river meets the sea/ at its mouth inwhich the river has been transporting its load. however, the river gradually loses energy and therefore has to deposit its load at the mouth, blocking the channel and causing the river to divide into smaller distributaries.

3 types of deltas - CAB

• CAB

• cupsate

• arcuate

• birdsfoot

cupsate delta - provide an example and describe the formation

formed when sediments are despoited onto a straight shore with strong waves, inwhich push the sediment to spread outwards and create a tooth shape.

eg - nile

arcuate delta - provide an example and describe the formation

fan/arc-shaped. Formed where wave action is not strong enough to completely redistribute sediments

eg. ganges

birdsfoot delta - provide an example and describe the formation

formed when rivers have lots of sediment - follows normal delta formation process

eg - mississippi delta

hazards/ disadvantages of living near rivers

• erosion

  • destory nearby housing, roads, farm

• risks of flooding

  • disease such as malaria from unhygenic and dirty water

  • water will encourage mosquitos and other insects to lay eggs - increasing risk of disease they may bring

  • wild animals inflitration of villages such as snakes and crocidles

  • destruction of valuable and or expensive resources

    • hospitals and schools

    • equipment

  • death

    • some cant swim - drown

    • some misjudge water depth and velocity - water swallows em a

    • starvation

      • food resource scarcity

perks/ advantages of living near rivers

• fertile soil

  • farming of valuable crops bywhich farmers can sell to make larger profits

• transportation

  • Residents can trade with nearby towns

• flat land

  • benefits construction by providing stable base/ ground

• attractive scenery

• peaceful

  • no distractions

• diverse options recreational activties

  • fishing, kayaking, paddling

indus river general info

• over 5 mil people lived

• nearly 270 million people depend on it as a water source

• Countries:

  • The Indus River flows through China, India, and Pakistan. It also passes through the disputed region of Kashmir and has a small portion in Afghanistan.

• Source:

  • The river originates near Lake Manasarovar on the Tibetan Plateau in western China. It is also associated with the Upper Gê'gyai source in the Ngari Prefecture.

• Course:

  • The Indus River flows northwest through the Himalayas and Karakoram mountain ranges, then southward through Pakistan. It passes through regions like Ladakh, Gilgit-Baltistan, Khyber Pakhtunkhwa, Punjab, and Sindh before emptying into the Arabian Sea near Karachi.

• Length and Basin:

  • The Indus River is approximately 3,180 kilometers (1,976 miles) long and has a vast drainage basin covering about 1.12 million square kilometers across the four countries.

• Tributaries:

  • The river has several major tributaries, including the Kabul River, Jhelum River, Chenab River, Ravi River, and Sutlej River.

hard engineering

the construction of expensive artificial structures to try and manage the flow of a river

examples of hard engineering

• dams

• resovoir

• flood relief channels

• straightening channels

• Embankments/ artificial levees

• River dredging​ - River dredging is the process of removing sediment, debris, or other material from bed

• Bridge design​

advantages and disadvantaes of hard engineering

• adv

  • immediate result (protection against erosion and floods)

  • Visibility provides a higher sense of protection for people

• dis

  • expensive

  • not enviormenta friendly

  • possibility of failure

    • worsen floods

  • alteration of natural enviorment

soft engineering

the use of natural and environmentally friendly processes to manage a river and not artificial construction

gorge

narrow and deep valley caused by waterfall retreat

examples of soft engineering

• afforestation (planting more trees)

• floodplain zoning

• warnings and preparation for floods

adv and disadv of soft engineering

• adv

  • enviormentally friendly

  • has less impact on enviormental

  • does not involve the construction of large, unaesthetically pleasing structures

  • protects biodiversity, ecosystem and landscape

  • offer long term solutions

• disadv

  • might not provide enough protection against severe floods

  • longer development duration

How does water get into a river in the first place? ​

1. Leaves and branches catch rain. This is called interception.

2. If ground is hard or very wet, rain flows overground. This is called surface run-off (overland flow).

3. Rain soaks into the ground. This is called infiltration.

4. Some water flows through the soil as throughflow.

5. Some water continues into solid rock to form groundwater. This flows slowly as groundwater flow.

6. A mixture of surface run-off (overland flow), throughflow and groundwater flow feeds the river.

factors affecting discharge

indus river

• Causes of the Floods:

  • Unusually heavy monsoon rains in the Khyber Pakhtunkhwa region

  • Exacerbated by deforestation, poor river management, and infrastructure failures

• River Management Issues:

  • Impact of dams and barrages on water flow and sedimentation

  • Levee failures, notably the breach at the Tori Bund, worsened the disaster

• Impacts of the Floods:

  • Nearly 2,000 fatalities and displacement of around 20 million people

  • Destruction of over 1.2 million homes and loss of livelihoods for millions

  • Estimated economic loss of approximately $43 billion USD

  • Destruction of over 2 million hectares of crops like cotton, rice, and sugarcane

• Responses and Management:

  • Emergency response led by the NDMA and military with rescue and relief operations

  • UNDP's Early Recovery Programme for restoring livelihoods and critical infrastructure

  • Challenges in the long-term recovery process due to inadequate community involvement, lack of resources, and poor coordination among stakeholders

why do floods occur

• destruction of flood prevention tatics (dams, resoviors, levees)

• ill preperatation

• heavy rainfall

• river channel blockage

• rapid melting of snow

what are artifical levees called

embankments

what is dredging

process of removing sediment and or other materials from river bed

things to include when asked ‘describe location of…’

• compass points

• use key

• name structures if applicable

define solution

when water dissolves coarse/fine material from bed an dbanks

name the 3 river processes

• deposition

• transportation

• erosion

define hydraulic action

when the river is at high velocity, the water seeps into cracks within the bank, causing a breakage.

define abrasion

when rocks and stones grind against the river bed and bank, causing gradual wear

define attrition

when rocks and stones clash against eachother, knokcing bits off of eachother

define load

eroded material

define sediment

load that is despoited by the river

define solution

water dissolving minerals from bed and banks