Using the information system and multi criteria

Proceedings of the Second World Landslide Forum – 3-7 October 2011, Rome

Eliene Coelho(1), Luciana Pascarelli(2)
Using the information system and multi-criteria
analysis in the geological risk management in São
Paulo
(1) PMSP, São Paulo City Hall, Habisp, Sao Paulo, Brazil.
(2) Consultancy Services and Technical Works Department, Sao Paulo City Hall, Rua Libero
Badaro, 425, Brazil

Abstract Since 1980´s the surveys space could not 355 km2 to 1.370 km2 in approximately five decades.
definitely follow the growth and the density of favelas, Due to the method adopted by real estate speculation
and some communities started to trigger the first when it came to dividing the land in the city, “urban
records of accidents in areas hitherto stable. The vacuums” were generated and subsequently occupied by
mapping made in 2010 is today the largest geological- shanty towns and irregular land occupation. Areas of
risk database in the country. Today, all these greater environmental fragility, such as slopes and
information are included in the “Habisp”. Habisp is a banks of streams also began to be occupied, above all at
mapping system of precarious settlements in the city of the end of the 1970´s. At the end of the 1980`s, there
Sao Paulo, which contains valuable information to face exists a record of the first accidents on slopes and in the
the urban poverty. Poverty which is materialized in Sao mid 1990´s, these become ever more frequent and less
Paulo in many ways of informal settlements: slums, localized, revealing that a considerable part of the
irregular settlements, tenement housing, temporary population occupies these areas of risk.
housing and degraded sets. The Habisp stores,
organizes, processes and produces high quality Mapping the risk areas in the city of São Paulo
geographic information, which serves as support for the
technicians of the Housing department in making At the end of the 1990´s, geotechnical companies
carried out an analysis of the risk on the slopes of 240
decisions. The results have been making possible
shanty towns, identifying about 60% of the situations at
reassessment and adjustment of the low-income
intervention projects by the government, prioritizing risk for landslides. Although such information has been
used for the planning and execution of local
housing, social-educational infrastructure, and basic-
interventions, activities to control and prevent such
sanitation actions in areas of greatest susceptibility.
risks per se have been negligible for about a decade
Keywords: mapping, susceptibility, geographic (1993 to 2001), whilst at the same time the occupation of
the hills grew significantly. Cartographic registries and
information, priority
those of occurrences were also rare, making it
impossible to carry out any sort of planning with the
The risk of landslides in large urban centers
necessary efficacy.
Mass movement processes are natural and a part of the In 2010, the City Hall of São Paulo, along with the
cycle/depositional erosion responsible for determining Institute for Technological Research (IPT) came to the
the scenery of the Earth’s surface. Nevertheless, when as conclusion of the need for “Analysis and risk mapping
the result of a geological process there is an impact on associated to landslides in the areas of slopes and the
human beings or their property, what comes to light is banks of rivers and streams in shanty towns in the São
the concept of a geological accident, implying that Paulo municipality”. More than a geotechnical survey,
besides the physical process some causes of instability the mapping geared its focus on the areas of precarious
also lead to the consequences observed. The first tales occupation, where the population’s vulnerability was
of accidents of this sort in the city of São Paulo relate to the steepest. In such sites, any type of event, even the
urban expansion. More fragile areas, such as slopes and minor ones could entail significant damage for the
river banks began to be occupied without the community, vis-a-vis their low perception of risk and
appropriate planning, and the growing number of the inability to set forth a speedy response and recovery.
people affected by the landslides revealed that there was The risk estimates were analyzed quantitatively,
a considerable part and parcel of the population living based on field observations, integrating the analysis
in risky settlements. parameters contained on a risk card, with the support of
In the city of São Paulo, the first tales of accidents aerial images.
of this nature are directly linked to the urban expansion The 407 areas investigated were subdivided into
recorded since the beginning of the 1930´s. According to risk sectors, due to the fact that the characteristics of
Nogueira (2002), the urban spot in the city grew from the land and above all of the occupations posed

E. Coelho, L. Pascarelli - Using the information system and multi-criteria analysis in the geological risk management in São Paulo

enormous variations within a single shanty town. For land settlements, tenements or slums and housing
each of the sectors, what was evaluated was (1) natural enterprises conceived for the population that lives in
parameters referring to the type of soil topography, those areas.
natural structures that conditioned land movements, To understand how it operates, it is necessary to
typology of water courses and type and breadth of explore some conceptual issues regarding the
vegetation and (2) occupational parameters such as the importance of Information and Communication
level of interference in the land, the presence of basic Technology (ICT) in our present day society. It is also
infrastructure to supply water, garbage collection and necessary to refer to the issue of making decisions, the
sewage treatment, the condition of public roads and construction of indicators and their content, objectives
structure of the homes themselves. Additionally to the and the dynamism relating to the problem of which it is
signs of instability observed, the parameters assessed a part: popular housing.
ended up in the creation of 1.179 risk sectors, with Habisp arose from an initiative to draw up a
specific levels of criticality according to Table 1. strategic plan for social housing, within the realm of the
project with Alliance with Cities, and throughout the
Table 1: Criteria to rank the degree of risk (simplified from the studies, it turned into a proposal to draft a Municipal
IPT- 2006) Housing Plan (MHP). Without the Habisp and the
Degree of Description System of Priorities, both planning instruments, the
probability MHP would not have attained its present day level of
Slopes with little inclination (<17º), natural and sophistication and detail. The proposal encompasses
R1 on stable soils with low probability of having
goals and objectives to service housing needs until the
landslides. Absence of indices of instability. This
is the least critical condition. year 2024, including the cost for urbanization
Slopes with slight inclination with a medium interventions and land ownership regularizing and the
probability of having a landslide. There is construction of new housing units, settlement per
evidence already of incipient instability. If the settlement (consult the Municipal Housing Plan:
R2
existing conditions are maintained, there is a document for debate, www.habisp.inf.br, Figure 1).
slight probability that there will be destructive Data, information, indicators, knowledge
episodes occurring during intense rainfall. generation, decision making, geographic spaces,
Inclined slopes (>30º) point towards a high popular housing, regularization of land ownership,
potential for developing landslide processes. spatial analysis, maps, registries and population surveys
R3 There is a large amount of evidence regarding
are some of the issues that Habisp relates to. To classify
instability (cracks on the soils, levels of
subsidence of the soil, etc.)
it into a single system modality is not an easy task, these
Evidence of instability is expressive (quantity subdivide into categories, in accordance to the activity
and magnitude). This is the most critical they support, but Habisp does not fit into a single
R4 condition. Under such conditions, it is highly category, and can be deemed to be a system for
probable that there will be destructive events managerial information; a transactional processing
during intense episodes of rainfall. system or a decision making support tool (BIDGOLI,
1989, apud BARBOSA, 2002).
More than a geotechnical survey, this broader As part of this classification set forth by Bidgoli
mapping already carried out in Brazil focused (1989, apud BARBOSA, 2002), we can state that Habisp
exclusively on settlement areas where the population’s is mostly a management information system, that can
social vulnerability was high. In these sites, any type of be used for planning, control and decision making
event, albeit the smallest ones could cause significant purposes; condensing or summarizing the information
damage to the community, given their low perception obtained from the transactional data processing
of risk and limited ability to respond to the event and systems, with routine and exception reports. The parcel
recover from it. of transactional processing systems in Habisp refers to
In real time, the data collected on the field, which the housing services part supported by this same system
included the perimeters of the areas analyzed, was (payment of benefits and issuing land ownership
entered into the Habisp system used the São Paulo regularization deeds for public areas). Nonetheless, one
City Hall since 2006. of its most relevant components, the system to
prioritize interventions, brings it closer or even
The Habisp system qualifies it as a system that supports the decision
making process, although this category so far does not
Habisp is an information system that works through the
have a broadly accepted definition.
web, with the ability to store and process alphanumeric
and geographic information. The focus is popular
housing and the “loci” are the shanty towns, irregular


with an extremely low compensation; consequently, this
means scant opportunities to have access to the formal
funding initiatives and their own housing.
Furthermore, the real estate market in São Paulo
has attained surreal levels of appreciation. The steep
prices are mainly due to the scarcity of supply or land at
compatible prices and locations. For those who are poor
in São Paulo (families generally with incomes falling
below three minimum wages), there are few
opportunities, and those that exist at present arise
precisely in precarious housing.

Figure 1: Picture of the first page on the Habisp System.
Source: www.habisp.inf.br.

The Housing problem in the large urban centers
Housing, in a very broad sense, is frequently deemed to
be key for the problem of poverty; a shanty town or
slum is the environment of a poor man according to the
operational definition officially adopted at a UN
meeting in Nairobi, 2002. It is characterized by an
excess of population, precarious or informal housing, Figure 2: Picture of the Jaguaré Slum. Archives of the
inadequate access to drinking water and sanitary Municipal Housing Secretariat – Sehab. City Hall of the São
conditions and insecurity as part of the ownership of Paulo Municipality.
this house.
Throughout the third world, the choice of housing What can be observed as a result of this
is a complicated calculation of ambiguous informality, is the greater occupation of areas that are
considerations. Like the famous phrase of the anarchist subject to environmental restrictions, areas of risk with
architect John Turner. “Housing is a verb”. The urban steep slopes or subject to flooding, contaminated soils,
poor need to resolve a complex equation upon areas close to sanitary landfills or garbage deposits,
attempting to optimize the cost of housing, guarantee among others, besides the concentration of a large
ownership, the quality of the shelter, distance from number of social problems, especially those linked to
work and oftentimes their own safety. And for all, the unsanitary conditions resulting from the absence of
worst situation is a poor and expensive area lacking in basic infrastructure, aggravated vis-à-vis the
public services and without the warranty of ownership vulnerability of its inhabitants, caused by factors
(DAVIS, 2006, p. 39). relating to informal employment, school abandonment
In São Paulo, occupation in precarious settlements or drop outs, early pregnancy, domestic violence and
- slums, irregular land plots or tenements – has been a drug trafficking.
part of the urban scenery for quite some time (Figure 2). If, for the low income population, there are few
The largest city in Latin America has one of the most alternatives and choosing becomes truly difficult, for
complex housing problems in the country; and for public management, this problem is further aggravated,
decades, facing up to this problem has posed a huge making intervention policies ever more complex. To
challenge for those in government. Concern with the have an anchor for public policies, what is needed, in
poor, urban poverty and popular housing mixes old and the first place, is detailed knowledge of which are the
new ideas during each period of history, and successive problems that will be faced, in the quest to qualify and
generations of reformists have struggled for the quantity the true needs. What does it mean to
elimination of slums. The difficulties, in the field of understand each of these low-income occupations in
housing management, land market and funding for their totality, but also in terms of their specificities,
housing for the low income population become evaluate the resources that are necessary to invest in
aggravated day after day, thanks to the economic and each of the housing projects or programs, so as to select
social problems that exclude the less specialized those which will make it possible to optimize public
population from labor markets, evermore demanding investment and attain the greater number of people
and that offer – when they offer – informal employment possible among the destitute population.

3


For the Sehab, the intervention strategies were shanty towns, as in principle the program cannot
clear, since work began to draft the MHP: urbanization regularize precarious situations, the focus shifted to
and regularization of shanty towns and irregular land acting upon areas with the best indices (COELHO and
plots occupied by low-income populations. However PÉREZ MACHADO, 2009).
there existed the need to particularize that extensive
universe of settlements, to know where to truly begin Table 3: Precarious settlements in the city of São Paulo:
each of the actions: that is to say, which slums to Conceptualization. Own draft. Altered by the CITY HALL OF
urbanize in the coming years? In the coming month? THE MUNICIPALITY OF SÃO PAULO; ALLIANCE OF
CITIES, 2008, p. 50.
With resources available at present? Because of this it
Informal occupations, self-built on the fringe of
was necessary to have surveys and more concrete data,
urban legislation, predominantly disorderly and
besides using analytical instruments with the ability to Favelas
with a highly precarious infrastructure. Occupied by
offer more precise answers on where and how this low-income families that are social vulnerable.
housing precariousness manifests itself. The Irregular occupations where the division of land
geographical aspect of the problem benefitted from the presents a layout that allows for the identification
use of spatial analytical instruments of proven efficacy, of a plot in comparison to a route of access. These
Irregular
and it became necessary to build a model that could Settlements
are done mainly on land that is predominantly
guide decision making, based on the existing data. privately owned and acquired through some sort of
The path chosen was to set forth indicators that marketing and may encompass all of the family
could be evaluated individually and offer immediate income brackets.
Multi-family collective housing made up of one or
responses, such as: degree of urbanization of a
more buildings subdivided into several rooms.
settlement, the population’s vulnerability, geological Tenements
Sanitary facilities, circulation and precarious
conditions etc., and that could be combined into a infrastructure, and generally overcrowded.
single index. Through this procedure, the intention was
to attain a goal to set up a decision making model that The report “Characterization, Classification,
would take into account the large diversity of variables Eligibility and Prioritization System for Interventions in
that existed in the context, and mainly the multiple Precarious Settlements in the Municipality of São
objectives that had to be reached. Four stages were Paulo/ Brazil (2007)” highlights two principles set forth
created to define the priority to service a specific for the selection of indicators and indices that jointly
settlement through a specific housing program: make up the prioritization index: (1) protection of the
characterization, classification, eligibility and population’s life and the enhancement of livability
prioritization, each with its own objective, as can be conditions to acceptable levels; and (2) protection of the
observed in Table 2. most vulnerable population socially. The same report
points out that the first formulations carried out by the
Table 2: Basic objectives of the phases proposed by the
Characterization, Classification, Eligibility and Prioritization
Sehab divided the priorities stepwise into three levels:
System. Own draft. (COELHO and PÉREZ MACHADO, 2009) high, medium and low, an approach that proved to be
Characterization Classification Eligibility Priorization lacking, as the universe of settlements demands a much
Characterize Classify these Select the Prioritize the larger scale, which led to the creation of a
the areas into areas that activities in “prioritization index”, that attributes a score between 0
precarious groups that will undergo those areas and 1 to each settlement, being that 0 is the absence of
settlements will guide the intervention, that fulfil the precariousness and 1 maximum precariousness based on
in the type of already eligibility a multi-criteria analysis model.
municipality intervention establishing criteria
The prioritization index is a summarized index
of São Paulo that is needed at this phase
that aggregates other indices through a weighted
a cut-off for
the actions method. Habisp has a logical matrix where the weights
are configured to calculate each of the indices that are
part of the system, thus allowing the administrator to
The first and foremost stage in the system is that interact with and validate the process, and also to adapt
of characterization, as the results found in future stages it to any change in the situations that may have an
will be ramifications of the information collected impact on the decision making process. In Formula [1]:
herein. Subsequently the work of updating the data (COELHO and PÉREZ MACHADO, 2009) we present a
began, as well as the conceptual definition of the types mathematical formula to calculate the prioritization
of settlements that would be serviced by the housing index for the urbanization program and for the
policy, described in Table 3 below. precarious settlement regularization program.
The principle adopted was simple: according to The indices used arise from several sources or
the objective of the action, the SEHAB defined the focus origins. Those of Health and Social Vulnerability were
of prioritization. For urbanization projects, the focus of appropriated by the Sehab from other initiatives, which
the action was the most precarious areas in all of the means to say they were not produced exclusively for the
issues analyzed. However, for the regularization of prioritization interventions, but serve as a benchmark


for sectoral policies in health and social assistance, at
the municipal sphere. The Paulista Social Vulnerability
Index (PSVI) bases itself on data from the 2000 IBGE
Census and the Health Index is based on data from the
municipal health system for 2006. The urbanization
index is calculated based on the data collected on the
field and inserted into Habisp, and updated whenever
the field team identifies changes in the situation
informed; this falls entirely under Sehab´s
responsibility.

Figure 3: Example of the overlay of the layer with the risk
IP = [(Y – IF) x nf]+(IR x nr)+(IV x nv)+[(Y – IS) x ns] mapping (2010) and the shanty town layer. Santa Madalena
(nf + nr + nv + ns) Park Slum. Source: www.habisp.inf.br.
[1]
Being that: Being that:
IF = urban infrastructure nf = weight of the urban
index infrastructure index
IR = index for risks of bank nr = weight of the washout and
washouts and landslides landslide index
IV = social vulnerability index nv = weight of the social
IS = health index vulnerability index
ns = weight of the health index

Y = Priority Ordainment Factor. (of growing order = 1) (if
decreasing order = 0)

Figure 4: Example of the interface to update data on the risk
Treatment of the landslide risk index in the sectors (2010). Source: www.habisp.inf.br.
prioritization system
Considering that the geological risk is a
The risk of washouts and landslides is founded on determinant factor to grant that condition of livability
survey carried out by the Foundation for Support to the to an area, the use of Habisp as an aid in the new
University of São Paulo (FUSP), through a partnership mapping has offered not only the possibility to create a
with the Institute for Technological Research (IPT), consistent data base on the risks in the city , but has
under the title of “Mapping the risks associated to also allowed for the speedy transfer of that knowledge.
washouts and landslides in slope areas and washout of Nowadays, delimiting the areas surveyed and the main
banks in streams in the shanty towns of the attributes that were part of the evaluation is
municipality of São Paulo, 2003”, in which the Housing information that can be accessed by technicians, as well
Secretariat participated in indicating those areas that as managers of municipal administration. The location
should be subject to analysis by the IPT team, along of the risk sectors and the degree of probability that
with the technical people (geologists, engineers and there will be a landslide is also available to universities,
architects) from the sub districts. research centers, non-government organizations
The Risk Index for the precarious settlements (NGO´s) and other stakeholders of this issue, through
nevertheless was conceived in the context of the Habisp.
prioritization system, and is calculated for each
settlement by using overlay operations (Figures 3 and IR=(Prb x nrb)/100+(Prm x nrm)/100+(Pra x nra)/100+(Prma x nrma)/100
4). The Habisp identifies, for each settlement, the nrma
2
percentage of its area (m ) that lies within each risk area [2]
and then, through a calculation formula [2], which
attributes a weight to each degree of risk, presenting the Being that: Being that:
risk index for wash outs and landslides for the specific Prb = % low risk nrb = weight of low risk
Prm = % medium risk nrm = weight of medium risk
settlement. ra
Pra = % high risk n = weight of high risk
Prma = % very high risk nrma = weight of very high
risk

5


The result of using HABISP can already be seen
in the major of government programs in progress. The
main one is the Municipal Housing Plan which can be
retrofitted quickly and the interventions, could be
reordered according to the risk areas in order to include
the elimination of the most serious risks by 2016
(including also the provision of financial resources for
such actions). Although the elimination of risks only in
the year 2016 may seem an unpromising scenario, the
recognition of this critical situation is optimistic
because it drives the municipality in search of more
resources and appropriate technical solutions that allow
shortening the schedule.

References
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(org). Brasília: Ministério das Cidades; Instituto de Pesquisas
Tecnológicas – IPT, 2007.
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instrumentos de gestão. São Paulo: Janeiro Projetos Urbanos,
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