1
DR. RAJIB BHATTACHARJYA
2//9/2011
CARRYING CAPACITY
EASTER ISLAND
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• Located 3500
kilometers off the
coast of Chile
• It is the world
world’s
s
remotest
inhabited island.
• Most
M t advanced
d
d
society with great
cultural heritage.
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Easter Island
Statue, built
around 700 AD
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EASTER
AS
ISLAND
S A
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| Discovered
by Polynesians ~ A.D. 1000
| Population grew to several thousands
y
y
y
Used trees for canoes to hunt dolphins
Usedd woodd for
f cooking
ki
Also ate birds, eggs, vegetables
| Resources
y
y
(trees) depleted
No canoes, no dolphins
Warfare over land, food resources
| Population
fell to 100 when visited by a Dutch in
1722.
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|
|
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BASICS ABOUT POPULATION GROWTH
The environment has a carrying capacity for every
organism based on the available resources
If resources are abundant and readily available
available, then a
population will show exponential growth
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| During
exponential growth the increase in
population size varies with the number of
individuals present
| Increase is gradual at first, but rises sharply
as more individuals become part of the
population
|U
Unlimited
e resources
eso ces allow
a ow everyone
eve yo e too
reproduce!
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ENVIRONMENTAL RESISTANCE
FACTORS
|
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|
Populations
p
will continue to g
grow exponentially
p
y
until they come up against limiting factors or
resistance factors
Resource limitations
Food, nutrients, water, sunlight
y Shelter,
Sh l
space
y
Competition
p
from other species
p
| Predation
| Waste accumulation
|
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LOGISTIC GROWTH
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| In
the real world resources are often limiting
| The first part of the growth resembles
exponential
ti l growth
th
| But over time, the population size levels off in
logistic
g
g
growth at a p
point called the carrying
y g
8
capacity
|
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CARRYING
CAPACITY
The carrying capacity
of the environment
represents the
maximum number of
individuals of a
particular species
that an area can
support indefinitely
without degrading
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CARRYING
CAPACITY
Natural populations seldom approach carrying
capacity
capac
ty ssmoothly
oot y
| Or stay at the carrying capacity once reached
| They usually fluctuate around the carrying
capacity
it
| Overshooting it or falling below depending on
resources
|
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ENVIRONMENTAL CARRYING CAPACITY
|A
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population gradually increase to the maximum
size that available resources will support—the
environment’ss carrying capacity.
environment
capacity
| Thereafter, the population fluctuates around this
size with g
good and bad cycles—e.g.
y
g rainfall.
Carrying Capacity = 10,000
12000
10000
Popula
ation size
• What
happens if
something
drastically
reduces this
population?
8000
6000
4000
2000
• What could
do that??
0
0
100
200
300
400
500
Time (years)
600
700
800
900
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1000
RECOVERY VS. REDUCED CAPACITY
| If
Recovery to Carrying Capacity = 10,000
12000
Population size
10000
8000
6000
4000
2000
0
0
100
200
300
400
500
600
700
800
900
1000
700
800
900
1000
Time (years)
Carrying Capacity reduced to 5,000
12000
10000
Population size
the population is
reduced because of a 1time catastrophe—e.g
catastrophe—e g a
long drought—then
over time it will recover
b k to its
back
i former
f
size.
i
| But if the overall
environment is
reduced—e.g. half the
forest is cut down—
then the population
adjusts to a new, lower
carrying capacity.
capacity
8000
6000
4000
2000
0
0
100
200
300
400
500
Time (years)
600
CARRYING CAPACITY
human population
recovered after the Black
Death—in fact the global
human p
population
p
has not
yet reached carrying
capacity.
| Salmon
S l
fish
fi h population
l ti
increases, then had their
habitat reduced by
y dams
and pollution. The
population had to adjust to
a much lower carrying
capacity.
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| So
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What is The Limit
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URBAN CARRYING CAPACITY CONCEPT
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Carrying capacity can be defined
as the number of individuals that
can be supported in a given area
without degrading the natural,
social, cultural and economical
environment of the area for the
present and future generation.
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SUSTAINABILITY
harvest sustainability
y refers
to the quantity of the resource that is
harvestable indefinitely.
| Ecosystem sustainability refers to
maintaining an ecosystem’s essential
functions and properties while harvesting
an ecosystem resource.
resource
| Sustainable economy maintains its level
of activity over time.
| Sustainable development requires the
integration of economic and social growth
and environmental protection.
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| Resource
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FACTORS EFFECTING URBAN CARRYING
CAPACITY
P
Environmental and
ecological
g
U b ffacilities
Urban
iliti
Carrying
Capacity
Institutional
Public
p
perception
p
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ENVIRONMENTAL CARRYING
CAPACITY
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Determining factors for
environmental carrying capacity
off an urban
b area are soil,
il slope,
l
vegetation, wetlands, scenic
resources, natural hazards, air
and water q
quality,
y, and energy
gy
availability, etc.
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URBAN FACILITY CARRYING
CAPACITY
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Housing, water supply
Housing
supply, sewage,
sewage
waste treatment, road network,
railway
il
networks,
t
k health
h lth care,
educational facilities,
employment facilities, etc. are
some of the factors that measure
the carrying capacity of urban
area.
area
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PUBLIC PERPETUAL CARRYING
CAPACITY
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The level of public awareness
awareness, which
generally includes human attitudes,
values,
l
b h i
behavior,
h bit etc.
habits
t
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INSTITUTIONAL CARRYING
CAPACITY
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The institutional carrying capacity
will be governed by the
governmental structure,
structure financial
stability, economy and cultural
limits on environmental decision
making, etc.
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FRAMEWORK FOR CARRYING CAPACITY
CALCULATION FOR HILLY AREA
Step1: Delineation of hilly area From the Master Plan
|
Step2: Demarcation of non developable areas based on
analysis of physical characteristics of the urban hilly area
and provision of different statute
|
Step3: Determination of area required for different
infrastructure and facilities like drainage network
provisions, water supply plants, sewerage and waste
treatment plants. This area requirement for infrastructure
will be a function of carrying capacity and will be
calculated iteratively
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|
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FRAMEWORK FOR CARRYING CAPACITY
CALCULATION FOR HILLY AREA
Step4: From the above calculation net area available for
residential development will be calculated
|
Step5: Determination of floor area required for each
person based on socio-economic status of the
prospective residents of the developable hilly area, habit,
daily water requirement and waste water generation,
amount of daily solid waste generated, market demands,
cultural activities and climate in the area
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|
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|
Step6: Based on above calculations carrying capacity of the study area may
b calculated
be
l l t d as stated
t t d below:
b l
Where, AH = Hilly area (as per step 1)
ANDA = Non developable area (as per step 2)
AIF= Area required for infrastructure and facilities (as per step 3)
FAR = Floor area ratio as prescribed in Master Plan, Building Bye-law
etc.
S = Floor area per person (as per step -5)
|
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CC = (AH – (ANDA + AIFCC) x FAR/S
Step7: Based on the population calculated in step 6 requirement of areas
for different infrastructure,
infrastructure facilities may be calculated using the set space
norms and adequacy of institutional frame work may be checked. Thus,
considering infrastructure, facilities and adequacy of institutional framework
final carrying capacity may be decided with time
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GIS APPLICATION
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Waterways
Natural Depression
Rocky land
High Slope Land
Total Watershed Area
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Total Developable area of the Watershed
Non developable area of the Watershed
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DETERMINATION OF CARRYING CAPACITY
BASED ON HYDROLOGICAL CAPACITY OF THE
WATERSHED
Determination of net density
y:
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|
Carrying Capacity (in persons)
Suitable Residential Area
|
Check for adequacy of drainage system,
sewerage system etc which were not explicitly
considered during carrying capacity calculation
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EXAMPLE FOR DRAINAGE ADEQUACY
+
Strom water
generation
from the
watershed
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Waste water
generation
i
from the
proposed
carrying
ca
y g
capacity
Check adequacy
of drainage
system
If inadequate
• Application of EMPs to reduce storm water
release
• Reevaluate the carrying capacity
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