11 Radial Sprawl Ribbon Sprawl Leapfrog Sprawl
Figure 2.1 Form of Sprawl In industrialized countries the future growth of urban populations will be
comparatively modest since their population growth rates are low and over 80 of their population already live in urban areas. Conversely, developing countries
are in the middle of the transition process, when growth rates are highest. The exceptional growth of many urban agglomerations in many developing countries
is the result of a threefold structural change process: the transition away from agricultural employment, high overall population growth, and increasing
urbanization rates Grubler, 1994. Mapping and quantification of urban sprawl provides a picture of location of
sprawl, type and patterns of sprawl, which helps to identify the environmental and natural resources threatened by such sprawls. Analysing the sprawl over a period
of time will help in understanding the nature and growth of this phenomenon and thereby visualizing the likely scenarios of future sprawl Sudhira et al., 2004a.
2.2.2. Urban Growth Driving Forces and Constraints
Urban growth driving forces can be simply defined as causes or factors influence for urban growth modeling and in the opposite, whereas constraints are
limitations imposed by nature or by human beings that do not permit certain action to be taken Keeney, 1980. Definition for each driving forces and
constraints for urban development in this study was explained below.
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1 Driving forces
a Neighbourhood effect
Urban form itself has a very heavy influence on the urban development. At a small scale, a city tends to grow in the areas
nearby the developed urban area. Neighborhood the total number of developed cells, in another word, the transition from non-urban to
urban was much affected by the adjacent area. If the vicinity of a cell is developed area, this cell has much higher potential to transit to
urban form if it was non-urban before.
b Road network
Road network have proved to be the key factor in urban evolution process. It heavily impacts the urban form and land price and even the
location of city center and sub-center. While the relationship between road network and urban form is far from clear. Closer the distances
from the city centre and the roads, the land has higher probability of becoming developed.
c Urban Hierarchy Index
An urban hierarchy categorizes centers according to their importance in terms of the functions that they provide. Functional importance is
reflected in the range and amount of services and facilities. There is usually but not always related to the size of the urban population.
Scalogram or Gultman Scaling is one of methods to ranks cities and municipalities in a region by their functional complexity based on the
number and types of facilities that are located within them Rustandi, 2008. The uses of the scalogram are to:
Categorize settlements into levels of functional complexity,
Determine the types and diversity of services and facilities,
Indicate the sequence in which settlements tend to accumulate functions,
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Show the degree of access that people have to services and facilities, and
Assist in deciding appropriate investment for settlements on a hierarchical basis.
d Slope effect
Ordinarily, built-up area will grow where there are flatten areas. The first assumption of this method is that some areas are not developed because they
are too steep. The second assumption is that increasing slope implies a higher building cost. With this assumption follow, that there should be a
lower percentage of cells within higher slope intervals, compared to lower slope intervals. In this case, slope will constrain the urban form mainly
depends on the slope.
2 Constrained factors:
Constraints are limitations imposed by nature or by human beings that do not permit certain action to be taken Keeney, 1980. The specification of
constraint is typically based on available resources and regulations and involves value or professional judgment.
The constrained factors indicate those limitations posed on the urban devel- opment such as water body is not allowed to develop into urban use, high slope
terrain is not suitable for urban use, reserved area and public green area is not allowed to transfer into urban, etc.
2.2.3. Markov Changes Detection
