Hydrosphere

Ground Water 0.62%

Soil water 0.005%

Ice 2.15%

Atmospheric Water 0.001%

97.2%

Evaporation

condensation Precipitation

Evapotranspiration

Infiltration

Water Table

Ice storage

Ground waterPercolation

Run off

Throughflow

• Evaporation: The transfer of water from the sea to the air as water vapour.

•Condensation: Water vapour (gas) changes back into water (liquid). It forms

small droplets which are visible as clouds.•Precipitation: Water falls to earth as either liquid (rain) or in a frozen state

(snow, hail).

•Stream / Surface Run Off: Most water returns to the sea in the form of

rivers.

•Evapotranspiration:

•Transpiration: The transfer of water from plants to the air as water vapour.•Ground water Flow: Some water returns to the sea as groundwater through soil

and rocks.•Infiltration: The point at which rainfall seeps into soil.

•Percolation: The seepage of water downwards through rocks.

•Throughflow: The movement of water downwards through soil back to the sea.•Groundwater Zone: Storage area for water which is slowly released back to the sea via springs and rivers.

Hydrological Cycle

River Basins

• Aims

Describe and explain the formation of key features of a rivers course with reference to specific erosional processes.

The Drainage Basin

The basic system of surface drainage is known as a river basin. This consists of a complex interaction of components which include rainfall, channel run – off , surface streams, soils, slope, solar energy, groundwater storage, evaporation from surface and evapotranspiration from vegetation. The system returns water to the oceans and seas as part of the hydrological cycle.

River BasinSource of River Clyde

Confluenceof River Clydeand tributary

Tributaryof River Clyde

Flood plain

Mouth ofRiver Clyde

Sea

Estuary ofRiver Clyde

Watershed of River Clyde(boundary between basins)

Sourceof river

UpperCourse

MiddleCourse

LowerCourse

Aims

Describe the physical characteristics of a river and its valley

Explain the formation of waterfalls, Vshaped valleys, meanders and oxbow lakes.

How rivers erode

HYDRAULIC ACTION / Water and air are forced into cracks on the river bank, exerting a pressure. When this process is repeated many times it causes erosion.ABRASION The material carried in

the river wears away the river bedATTRITION As the pebbles carried by

the river crash into each other,they become smaller and rounder

SOLUTION The water in the river dissolves the minerals in the rocks

Leave a space between each to draw a picture of the types of erosion.

How rivers transport

Rolling stones along the river bed.( needs lots of energy)

Traction

SuspensionClay sized particles are carried

along by the river flow

SaltationSand sized particlesbounce along the riverbed

SolutionSome minerals are

dissolved by the riverwater

river flow

Upper Course

Middle Course

Lower Course

Characteristics Upper Course Middle CourseLower Course

Slope

Width

Depth

Straightness

Main work

Valley width

Type of load

usually steep

narrow

shallow

winding

large/small angular

erosiontransportation

quite steep

quite wide

quite deep

meandering

medium/smallrounded

Transportation

narrow

gentle

quite wide

wide

deep

big meanders

small+rounded

transportationdeposition

wide

FEATURES OF THE UPPER COURSE

V-SHAPED VALLEYS WITH INTERLOCKING SPURS

POT HOLES ON RIVER BED

WATERFALLS AND RAPIDS

Upper CourseIn the upper course of the river the gradient is very steep and the river when flooded is fast flowing causing hydraulic action. The sides of the valley are steep and the main work is erosion.

The erosion process is greatest during periods of heavy rainfall as the river has more energy to affect the bedload as material is transported either by being rolled (traction) and bounced (saltation).

Upper course is also affected by climate (freeze – thaw), rock types (soft & hard), local vegetation and slightly acidic rain (corrosion) causing a chemical reaction which erodes away rock.

Interlocking spurs are fingers of hard rock that the river cannot erode, so it flows around

them.

Potholes are holes eroded in the river bed by stones being spun in the water (abrasion)

So how does a v-shaped valley form?1. Vertical erosion (in the form of abrasion, hydraulic action and solution) in the river channel results in the formation of a steep sided valley2. Over time the sides of this valley are weakened by freeze thaw weathering processes and continued vertical erosion at the base of the valley3. Gradually mass movement of materials occurs down the valley sides, gradually creating the distinctive v-shape.4. This material is then gradually transported away by the river when there is enough energy to do so.

As the river flows through the valley it is forced to swing from side to side around more resistant rock outcrops (spurs). As there is little energy for lateral erosion, the river continues to cut down vertically flowing between spurs of higher land creating interlocking spurs

So how does a v-shaped valley form?1. V________ erosion (in the form of a________, h____________ action and solution) in the river channel results in the formation of a steep sided valley2. Over time the sides of this valley are w____________ by f________ t_________ w_____________ processes and continued vertical erosion at the base of the valley3. Gradually m_______m____________ of materials occurs down the valley sides, gradually creating the distinctive v-shape.4. This material is then gradually transported away by the river when there is enough energy to do so.

As the river flows through the valley it is forced to swing from side to side around more resistant rock outcrops (spurs). As there is little energy for lateral erosion, the river continues to cut down vertically flowing between spurs of higher land creating interlocking spurs

Key Term CheckV-shaped Valley - a valley which resembles a 'v' in cross section. These valleys have steep sloping sides and narrow bottoms.

Interlocking Spur - spurs are ridges of more resistant rock around which a river is forced to wind as it passes downstream in the upper course. Interlocking spurs form where the river is forced to swing from side to side around these

http://www.cleo.net.uk/resources/displayframe.php?src=308/consultants_resources%2F_files%2Fintespur2.swf

Waterfall formationhttp://www.school-portal.co.uk/GroupDownloadFile.asp?file=21604

PLUNGE POOLUNDERCUTTIN

G OF SOFT ROCK

OVERHANG

WATERFALL RETREATS . .UPSTREAM . .

Picture Paragraph

• The river will slowly undercut the hard rock by eroding the soft rock underneath it.

• This is enhanced by the swirling of broken rock in the plunge pool underneath the over hang.

• The combined effect of falling water and the swirling rock erodes downwards – abrasion – and backwards Hydraulic action.

• As the overhang gets larger and protrudes further it will collapse under is own weight.

• The rock from the overhang will further erode the plunge pool.

• Repeated overhangs and collapses over time will result in a narrow, steep sided gorge.

1.Continuous erosion by the river will see the gradual undercutting of the slower eroding hard rock by the quickly eroding soft rock.

2.This is enhanced by the swirling of broken rock (eroded rock) in a plunge pool underneath an overhang.

3. The combined effect of the falling water and swirling rocks is to erode downwards – abrasion – and backwards- Hydraulic Action.

4. As the overhang gets larger and protrudes further it will eventually collapse under its own weight to form a new cliff.

5. The rock from the collapse will then be used to erode the resulting cliff and enlarge the plunge pool.

6. Repeated over time a series of overhangs and collapses occur, resulting in a steep sided & narrow gorge being formed.

1.Continuous erosion by the river will see the gradual u_______________ of the slower eroding hard rock by the quickly eroding soft rock.

2.This is enhanced by the s_____________ of broken rock (eroded rock) in a p_________ p__________ underneath an o_______________.

3. The combined effect of the falling water and swirling rocks is to erode downwards – a_________________ – and backwards- H_____________ A_____________.

4. As the overhang gets larger and protrudes further it will eventually c____________ under its own w___________ to form a new cliff.

5. The rock from the collapse will then be used to erode the resulting cliff and enlarge the p__________ ___________.

6. Repeated over time a series of overhangs and collapses occur, resulting in a steep sided & narrow g________ being formed.

FORMATION OF A WATERFALL

MEANDERS

Flood plain

Meanders

© Used with the permission of the Geological Survey of Canada

Available at http://sts.gsc.nrcan.gc.ca/clf/landscapes.asp

NARROW MEANDER NECK

FUTUREOX-BOW LAKE

Reproduced with the permission of the Controller of HMSO © Crown Copyright NC/02/15232

tributaries

ox-bowlake

meander

V shaped valley

SteepValleysides

Floodplain