4.4 South California

8/4/2019 4.4 South California

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Oxford Universit Press 2003 Certificate Ex lorin Geo ra h 2

Part 4

Irrigation Farming


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Part 4

Where is southern California?

It is situated in the west coast of the United States

It is the region which is roughly the area south of

San Francisco

Can you point out

the location of

California?

What come to your

mind when you think

of California?

San Francisco

Southern

California


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Part 4

What is the physical environment insouthern California?

Relief and drainage

Do you know the relief andthe drainage systems in

southern California?

Which places do you

think are suitable for

farming?

Sierra Nevada

Sacramento River

San Joaquin River

Colorado River

Imperial Valley

Central Valley

Coast

Ranges


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Extensive farmland on low-lying areas

between mountain ranges

Central ValleyImperial Valley

Water resourceCentral Valley

Sacramento River+ San Joaquin River

Imperial Valley

Colorado River

Reliefcomplicated and diverse ,

Highland of over 400 m >400

Coast RangesSierra Nevada


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Climate characteristics Temperature increases southwards ()annual temperature: 12 to 32 oC

Any spatial differences in

temperature within

California between thenorthern and southern

region?

Temperature


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-5

0

5

10

15

20

25

30

J F M A M J J A S O N D

(oC)

0

50

100

150

200

250

300

()

()

(oC)

In the central-Fresno Hot & dry climate

Mediterranean climate

Temperature Hot summer mild winter

, High annual mean

temperature: 26oC

,26oC Great diurnal range of

temperature (20oC)

(20)


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Precipitation Low annual rainfall

(about 260mm)

(260)

Distinct seasonaldifference (distinct dry

seasons in summer)

,

-5

0

5

10

15

20

25

30


(oC)

0

50

100

150

200

250

300

()

()

(oC)

In the central-Fresno Hot & dry climate

Mediterranean climate


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Part 4

In the north-FresnoLimited rainfall Locates on the Central Valley (rain shadow area)

() away from sea

(without maritime influence) () Affected by offshore wind

in summer (dry summer)

()



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In the south -Los Angeles Temperature

Hot summer warm winter

, medium annual mean

temperature: 19.5oC

,19.5oC moderate diurnal range of

temperature (10oC)

(10)

Cool and dry climate

Subtropical semi-arid/

continental climate /

-5

0

5

10

15

20

25

30


(oC

)

0

50

100

150

200

250

300

(

)

()

(oC)



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Precipitation Low annual rainfall

(about 381mm)

(381)

significant seasonaldifference in rainfall, but

without dry seasons

,

In the south -Los Angeles Cool and dry climate

Subtropical semi-arid/

continental climate /

-5

0

5

10

15

20

25

30


(oC)

0

50

100

150

200

250

300

()

()

(oC)



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In the south-Los Angelesmore rainfall than Fresno

Coastal location (maritime influence)

() Affected by offshore wind

in summer (dry summer)



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Reasons for a climatic variation?? Latitude

Distance from sea (coastal/ continental) (/) Prevailing winds

-5

0

5

10

15

20

25

30


(oC)

0

50

100

150

200

250

300

(

)

()

(oC)

-5

0

5

10

15

20

25

30


(oC)

0

50

100

150

200

250

300

()

()

(oC)



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Effects of prevailing winds

Onshore wind + mountainous regions higher rainfall + Offshore wind less rainfall



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NorthCalifornia

Central California

To difference:latitudinaldifference

To + R difference:latitudinal difference+ distance from sea

SouthernCalifornia



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NorthCalifornia

Central California

Rainfallthroughout

the year

SouthernCalifornia Scare rainfall

Imperial Valley

Warm moist winterHot arid summer

Mediterranean

climate

Desert-like/Semi-arid climate



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Spatial distribution pattern

of rainfall in CaliforniaRainfall decreases inland

Rainfall decreases southwards

coastal: Relief raininland: Rain shadow



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Soil High temperature

higher rate of evaporation

high salt content Alkaline Infertile



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Major farming (physical) constraints ()

Lack of water :~ dry climate~ inadequate water supply

Alkaline, infertile soil

Hilly relief with limited low flatland



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Climate

Temperature increases/

decreases towards the south

Study the temperatures of

different cities in California.

How would you describe the

change in temperature from

the south to the north?

Temperature




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Rainfall

Climate

Northernpart:

Centralpart:

Southernpart:

Rain all year round

Summers are hot and dry,

and winters are warm

and wet

Scarce rainfall

Mediterranean

climate

Desert-like climate

Rainfall decreases from the coast

towards inland

Rainfall increases/decreases southwards

Are there any difference in

rainfall in different places

in California?

Relief rain

Rain shadow effect

Coastal regions:Inland regions:




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Soil

Alkaline

Infertile

High

temperature

High evaporation

rates

Soil with large

amount of salt


P 4



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Where do people farm in southernCalifornia?

The most productive

areas:

Central

Valley

Read the map carefully. Do

you know where is the most

productive area in southern

California?

Coachella Valley

Central

Valley

P t 4



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Mainly fruits, vegetables

and cotton

What do people farm in southernCalifornia?

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What are the characteristics of

the physical inputs?

What is the irrigation farming systemin southern California?Physical inputs

1 Climate

Temperature: 1232 Annual

rainfall:

,

about 200400 mm

2 Soil

and infertile3 Land

Extensive lowland in the

Valley, the CoachellaValley and the Imperial Valley

4 Water supply

From the River and

the Colorado River

5 Seeds

Low/Scanty

Alkaline

San Joaquin

Characteristics

Dry climate

Inadequate water

supply

Lack of lowland for farming

Infertile soil

Central

P t 4



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Cultural inputs

1 Labour Contract workers

2 Capital

High investment

3 Irrigation

Water schemes such as

reservoirs, dams and

canals, provide water

for irrigation

Use of machinery

Characteristics

Most of them are

Mexican origin

To ensure sufficient

_________ resources

- intensivefarming practice

What is the irrigation farming systemin southern California?

Capital

water

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4 Chemicals

Use of pesticides and

fertilizers

5 Research and technology Develop new species of

crops which give higheryields

6 Government aids Local government

provides subsidies

To ensure output

per hectare of farmland

Government aid to

farming through

different policies

To improve the

of farm production

Reduce production

high

costs

output

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Processes

Specialize in one or

two cropsFarm outputs are sold at

home and abroad

1. Farming activities, such as ploughing, seeding, planting, irrigation, pest control,fertilizing, harvesting

2. Specializationand commercialization


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Good linkages with markets

Trains and trucks with

refrigerated facilities What are thecharacteristics of the

output?

Outputs

1 Commercial crops, such as fruits, vegetables,

cotton and nuts


2 Waste, such as unused parts of the crops

Well connected with other parts of the country by

andrailroads roads

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High output systemHigh input of capitalHigh input of technology

High

productivity

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How can technology facilitate thehigh-output system in southern

California?

Irrigation system

Use of farming machinery

biotechnology

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Why agricultural activities are well-

developed even though there are natural

constraints in southern California?

Farmers use advanced farming to

overcome the agricultural constraints in southernCalifornia

technologies


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What agricultural technologies areused to overcome agricultural

constraints in southern California?

Agricultural technologies

Mechanical

improvementApplication

of chemicalsBiological

innovationEnvironmental

improvement

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What are the problems and limitations of technology

What are the problems caused by irrigation?

Rapid evaporation

(hot, dry climate)

high salt content in the soil

(salinization)land becomes unproductiveUse of windmills to tape

ground water for irrigation,

fall of water table

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Ground water may be polluted

with salt and toxic chemicalsExcess irrigation leads to soil

erosionWashing away of chemicals

leads to water pollution

A lot of ground water is tapped, the water table falls and the

land subsides land subsidence

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What are the problems caused by the use of chemicals?

How does a normal

water ecosystem () looklike?

What are the problems and limitations of technology?

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How do excess nutrients

cause eutrophication in

water ecosystems? Too muchfertilizers is usedExcess fertilizers is

washed into riversExcess growth of algae

Level of oxygen

falls

Death of most living things

High level of nitrates in

drinking water affects the

health of children!Eutrophication

What are the problems caused by the use of chemicals?

What are the problems and limitations of technology?

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What are the problems caused by the use of

chemicals?

Start

here

More pest

problems

Use of chemical

pesticides

Increased

resistancePest

problems

Use of more

chemical

pesticides

Moreincreased

resistance

More pest

problems

Use of more

chemical

pesticides

More

increased

resistance

More pest

problems

And on and on, and on

What are the problems and limitationsof technology?

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What are the problems caused by using biotechnology?

Do not have enough data to tell whether genetically-modified food is

harmful or notDo not have enough data to tell what effects will be caused to agro-

ecosystem by introducing genetically-modified cropDo you like to eat maize which has the

genes of spider?Is genetically-modified food safe?

What are the problems and limitationsof technology?

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How can we sustain a balance between theuse of technology and the environment?

A high-input, high-output farming systemHigh demand for resourcesEnvironmental costs involved are very high

Manage farming practices in a more sustainable

wayDecrease the dependence on excess use of

water for irrigation, chemicals and fuels

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Precision agriculture

Means Advantages

Field conditions for crop growth are

measured and recorded

Nutrient levels, soil texture and chemistry,

moisture content and pest pattern

Provide precise and valuable data for

farmers to plan their work

Examples Drip irrigation system

Calculates and applies the necessary

amount of water, nutrients and pesticides

for individual plants

Reduce the use of chemicals Reduce pollution of underground water

Reduce waste of resources and thus

increase profits

Save energy

Reduce environmental damage

Use of computers and other information technologies

to assist agriculture


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a t

Means Advantages

Field conditions for crop growth

are measured and recorded Nutrient levels, soil texture

and chemistry, moisture content

and pest pattern

Provide precise and valuable

data for farmers to plantheir work

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Examples

Drip irrigation system

Calculates and applies the

necessary amount of water,nutrients and pesticides for

individual plants

Reduce the use of chemicalsReduce pollution of

underground waterReduce waste of resources andthus increase profitsSave energy

Reduce environmental damage

Means Advantages

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Organic farmingUse natural methods of pest control and apply

manure to the soilOrganically grown crops are more healthyMajor organic farm produce in California:

Flowers Fruits

Demand for organically grown crops is increasing


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What are the differences between farmingin the Sahel and in southern California?

300600 mm

Highly variable and unreliable

200450 mm

Variable and unreliable

Using few machines and little

technology inputs

Using computers to control

irrigation devices, chemical

fertilizers and pesticide, and

biotechnology

Characteristicsofthe

farmingsystem

Conditions The Sahel Southern California

Rainfall pattern

Economic

development level

( More developed/Less

developed )

( More developed/Less

developed)Intensity of

farming( Intensive/Extensive ) ( Intensive/Extensive )

Type of

farming( Pastoral/Arable ) ( Pastoral/Arable )

Capital

inputs( Large/Small ) ( Large/Small )

Level of

technology( High/Low ) ( High/Low )

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Removal of natural vegetation

Soil is destroyed by trampling

Desertification

Land degradation

Salinization

Eutrophication

Land subsidence

Toxication caused by pesticides

Biotechnology causing

confusion in agro-ecosystem

improved grazing technologies,

investment in infrastructure

carrying out import barriers

and export assistance policies

Milk, hides, meat Fruits, vegetables, nuts, cotton

What are the differences between farmingin Sahel and in southern California?

Characteristics

ofthefarming

system

Conditions The Sahel Southern California

Reliance on

irrigation

( Heavy/Little ) ( Heavy/Little )

Farm

produceGovernment help ( Much/Little ), e.g. ( Much/Little ), e.g.

Man-land

relationship

( Adapt to/Modified ) the

natural environment

( Adapt to/Modified ) the

natural environment

Impact on the

environment

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Government policies (Table 1 on p. 44

Import barriers and export assistance policies~ Import tax~ quota limit on export

Input assistance~ subsidies on production cost~ loans / tax concession/

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Direct payments

Agricultural research , infrastructure/land improvements~provision of technology and management skill

Other assistances~ export assistance

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Large-scale water projectsAqueductsSacramento River(California + LosAngeles)Colorado River(Colorado)canalsColorado River(All-American Canal)Dams & Reservoirs +

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Small-scale irrigation methods

Gravity flow systemsIrrigation water isdrained into the

furrows and the water

flows downslope due

to gravity

Environmental improvement

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Gravity flow systemsThe sprinkler systems


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Gravity flow systemsThe sprinkler systemsThe drip irrigation systems

Use of small tubes with

pinholes to drip waterto the root zone of a

crop with the aid of

computer

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BiotechnologyGenetic engineering

GM food Source of introducedgenes Advantages

Potato Chicken Disease-resistantTomato, maize Spider, scorpion Pest-resistantStrawberry Bean, tobacco Fungi-resistantApple Chicken, bacteria Disease-resistant

Biological innovation

Examples:

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Mechanical improvement

Use of computers in farming operations

Use of computers to control irrigation systems

Time of irrigationAmount of irrigation water

Mechanical planting

Ploughing machinesCombine harvesters

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Pesticides

Fertilizers

Reduce crop failureImprove crop yield and qualityLower production costs

Application of chemicalsExamples:

4.4 South California

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