In the recent
years, a lot of thrust in this field has been to understand and analyse the
urban sprawl pattern. Various analysts have made considerable progress in
quantifying the urban sprawl pattern (Theobald, 2001; Lata et al., 2001; Torrens
and Alberti, 2000; Batty et al., 1999; Barnes et al., 2001). However, all these
studies have come up with different methodologies in quantifying sprawl. The
common approach is to consider the behaviour of built-up area and population
density over the spatial and temporal changes taking place and in most cases the
pattern of such sprawls is identified by visual interpretation methods.
Defining this
dynamic phenomenon with relative precision and accuracy for predicting the
future sprawl is indeed a great challenge to all working in this arena. One of
the basic and major challenge is quantification of such sprawl. Although
different sprawl types were identified and defined there has been an inadequacy
with respect to developing mathematical relationships to define them. Further as
if aggravating this problem, much of the work related to studying dynamics of
urban sprawl are not carried out in the developing countries, except a few.
Thus, giving very little relevance to correlate the available findings in the
context of developing countries. However, the negative impacts of such urban
sprawls in developing countries are more severe and intense compared to that of
developed countries. Typically, the developing countries are faced with an
unprecedented population growth and potentially threaten vast natural resources.
In such a scenario, it is definitely an exacting effort to study, characterise
and model the urban sprawl phenomenon in the context of developing countries.
This study is an attempt in understanding the urban sprawl phenomenon, pattern
recognition and modeling studies as well.
Urban sprawl
dynamics was analysed considering some of the causal factors. The rational
behind this is to identify such factors that play a significant role in the
process of urbanisation. The causal factors that were considered responsible for
sprawl were:
Population (POP99), |
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a Population density (POPADEN) and b Population density (POPBDEN), |
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Annual Population Growth Rate
(AGR) |
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Distance from Mangalore (MANGDIST)
and |
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Distance from Udupi (UDUPIDIST) |
Population has
been for long accepted as a key factor of urban sprawl. The percentage built-up
is the proportion of the built-up area to the total area of the village. The
a
population density (POPADEN) is the proportion of the population in every village
to the built-up area of that village. The b
population density (POPBDEN) is the proportion of population in every village
to the total area of that village. The b
population density is often referred as population density. Since the built-up
area plays an important role in the current study for the purpose of analyses,
the percentage built-up, a and b population densities are computed and analysed village-wise and categorised
as a sub-zone. The annual population growth rate (AGR) is computed from the
population data available from 1961 for all the villages. This growth rate is
used in predicting the population for 1999 and subsequent future populations.
The distance from the city centres, viz. Udupi and Mangalore to each village
was calculated. Thus, the effects of proximity of the cities on the urban sprawl
of these sub-zones were analysed. With these causal factors identified the modeling
studies were undertaken.
In order to explore the probable relationship of
percentage built-up (dependent variable) with causal factors of sprawl
(population, a and b population densities, etc.), regression analyses considering linear,
quadratic (order=2), and logarithmic (power law) were tried and the results are
tabulated in Annexure.
The regression
analyses revealed that the population shows linear relationship (y = a*x + b)
and plays a significant role in the sprawl phenomenon. The quadratic regression
analyses for second order were undertaken. All the causal factors were
considered and the regression was carried out for the square of causative
factors (e.g. When 'y' is the dependent variable and 'x' is the independent
variable, then a polynomial regression of second order will be of the form, y =
a*x2 + b*x + c). The quadratic regression analyses revealed that the
population b
density and distance from urban centre (Mangalore) have a significant role in
the sprawl phenomenon. The logarithmic (power law) regression analyses were also
undertaken. The same causal factors were considered and the regression was
carried out for the natural logarithmic of the causative factors (e.g. When 'y'
is the dependent variable and 'x' is the independent variable, then a
logarithmic regression will be of the form, log y = log a + b * log x; or y = a
* xb). The logarithmic regression analyses revealed that the
population b density has significant role in the sprawl phenomenon.
The probable
relationships are
PCBUILT
= 0.000611*POP99 + 10.87149 (r = 0.5789)
............2
PCBUILT =
0.005651*(POPBDEN)2 - 1.2*10-7*(POPBDEN) + 6.8950 (r = 0.6823)
.............3
PCBUILT =
-1.7953*(MANGDIST)2 + 0.02593*(MANGDIST) + 36.8607 (r =
0.60).............4
PCBUILT
= -0.9027*(UDUPIDIST)2 + 0.002242* (UDUPIDIST) + 15.9731 (r =
0.583).............5
PCBUILT
= 0.270 * (POPADEN)1.6938 (r
= 0.4779) .............6
Multivariable
linear regression analysis was done to assess the cumulative effect of causal
factors. The multivariate regression analyses reveal that all causal factors
have a significant role in the sprawl phenomenon. Probable relationships are,
PCBUILT
= - 27.08 + 0.002496*POPBDEN + 0.5743*MANGDIST + 0.8139*UDUPIDIST
(r
= 0.719) ............7
PCBUILT = -
18.9358 - 0.00027*POP99 + 0.005452*POPBDEN + 0.3797*MANGDIST + 0.6249*UDUPIDIST (r = 0.761) ............8
PCBUILT =
-38.6985 - 0.00031*POP99 + 0.006024*POPBDEN - 1.677991*AGR + 0.7577*MANGDIST
+ 1.0346*UDUPIDIST (r = 0.784)
............9
PCBUILT = -
21.7633 - 0.00031*POP99 - 0.12529*AGR - 0.0004*POPADEN + 0.006417*POPBDEN +
0.5289*MANGDIST + 0.7451*UDUPIDIST (r = 0.86) ...........10
Likely increase
in the built-up area is predicted using Equation 9. To project built-up for
2020 and 2050 corresponding population was computed considering annual growth
rate based on the historical population data of 1961-2001.
It is found that the percentage built-up for 2020 and 2050 would be 18.10 % and 30.47 % respectively. This implies that by 2050, the built-up area in the region would rise to 127.7 sq. km, which would be nearly 106 % growth in the change in built-up area to the current sprawl of 61.7703 sq. km over the region. Thus indicating that the pressure on land would further grow and the agriculture fields, open grounds and region around the highways would become prime targets for sprawl. This would also give a picture of the pressures on the land for which the planners have to address in their planning exercises. With an understanding of the land requirement under the current trend the techniques of GIS and remote sensing can be applied for effective infrastructure facilities and resource utilisation.
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