4.4 south california
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Irrigation Farming
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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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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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What is the physical environment insouthern California?
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
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
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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
J F M A M J J A S O N D
(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
J F M A M J J A S O N D
(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
J F M A M J J A S O N D
(oC)
0
50
100
150
200
250
300
(
)
()
(oC)
-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)
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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
What is the physical environment insouthern California?
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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:
What is the physical environment insouthern California?
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Soil
Alkaline
Infertile
High
temperature
High evaporation
rates
Soil with large
amount of salt
What is the physical environment insouthern California?
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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
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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
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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
What is the irrigation farming systemin southern California?
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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
What is the irrigation farming systemin southern California?
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
What is the irrigation farming systemin southern California?
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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
How can we sustain a balance between theuse of technology and the environment?
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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
How can we sustain a balance between theuse of technology and the environment?
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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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Small-scale irrigation methods
Gravity flow systemsThe sprinkler systems
Environmental improvement
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Environmental improvement
Small-scale irrigation methods
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: