Area and population of urban formal and informal settlements

(a)Name:  Area and population of urban formal and informal settlements.
(b)Brief Definition:  Urban residential area in square kilometres occupied by
formal and informal settlements, and the number of their occupants.
(c)Measurement Unit:  Area: km2;  number of occupants.

(a)     Agenda 21:    Chapter 7:  Promoting Sustainable Human Settlement
Development. 
(b)     Type:  State.

(a)     Purpose: The indicator measures both the sizes of informal urban
settlements and the residential density of both formal and informal
settlements. By focusing on the legality of human settlements, this indicator
measures the marginality of human living conditions.

(b)     Relevance to Sustainable/Unsustainable Development: Settlements
characterized by illegality of tenure and unauthorized shelter are generally
marginal and precarious, and do not cater for basic human needs such as
affordable housing. They affect sustainable human settlements development,
human health, and socioeconomic development. 

Illegal dwellers generally live in an unsafe and precarious environment, lack
basic services, suffer from the absence of tenure security, and have no legal
claim in case of eviction. Also, numerous illegal settlements are established
on lands which are predisposed to natural disasters. Informal settlements have
usually a much higher population density than formal settlements and these
living conditions constitute a threat to human health. 

(c)     Linkages with Other Indicators:  This indicator is closely linked with
several other socioeconomic and environmental indicators, such as rate of
growth of urban population, human and economic losses due to natural
disasters, access to adequate sanitation, primary health care, infant
mortality, infrastructure expenditure, and land use.

(d)     Targets:   No international targets have been established for this
indicator.

(e)     International Conventions and Agreements:   Not applicable, see
section 3d above.

(a)     Underlying Definitions and Concepts:  Informal settlements refer to:
i) residential areas where a group of housing units has been constructed on
land to which the occupant have no legal claim, or which they occupy
illegally; ii) unplanned settlements and areas where housing is not in
compliance with current planning and building regulations (unauthorized
housing). Formal settlements refer to land zoned residential in city master
plans or occupied by formal housing.

(b)     Measurement Methods:  Households and population living in informal
settlements are generally measured in censuses. Area of informal settlements
can be evaluated through aerial photography or land use maps. This indicator
should not cover dwelling units which have been regularized, that is those
units for which land titles, leases or occupancy permits have been granted.
It should only include those units which presently occupy land illegally
and/or housing units which are not in compliance with current regulation. 
Where feasible, the interpretation and meaning of this indicator would be
supported by the comparison of informal settlement area and population to
total urban area and population. 

(c)     The Indicator in the DSR Framework: This is a state indicator,
reflecting the major consequence of unplanned and unsustainable population
growth in human settlements.

(d)     Limitations of the Indicator:  The ephemeral nature and lack of an
acceptable operational definition for this indicator, limit its usefulness,
especially for trend analysis.  The legal framework for settlements on which
this indicator is based varies from country to country. Informal housing is
not registered in official statistics, any measure of informal settlements
remains limited. Information may be obtained from specific research studies,
but it difficult to obtain and may be of variable quality. Homelessness, which
is one of the extreme symptoms of human settlements inadequacy, is not
accounted for by this indicator and in fact the existence of illegal
settlements may reduce the incidence of homelessness. This indicator does not
cover informal settlements in rural areas.

(e)     Alternative Definitions:  Many concepts intended to measure
marginality of human settlements have been formulated: unplanned, squatter,
marginal settlements, unconventional, non permanent structures, housing in
compliance, inadequate housing, slums, etc. "Unconventional dwellings" is one
of the most common measures, defined by the number of housing units occupied
by households, but considered inappropriate to human habitation. The type of
building (permanent, semi-permanent, non permanent) which describe the
building structures in which households live is another common measure, but
the criteria widely vary from country to country.  Alternatively, attempts
could be made to include informal rural settlements within the indicator
concept.   This would be more comprehensive, but detract from its urban focus.

(a)     Data Needed to Compile the Indicator:  Area and population of informal
settlements.

(b)     Data Availability:  These data are more likely to be available at the
city level and are generally collected in large cities affected by informal
settlements.  Data sets at the national level will only occur sporadically.

(c)     Data Sources:   Data from research studies, census data, and aerial
photographs.

The lead agency is the United Nation Centre for Human Settlements (Habitat). 
The contact point is the Director, Programme Coordination, Habitat;  fax no.
(254 2) 624 266. 

World Bank. Housing: Enabling Markets to Work. A World Bank Policy Paper. The
World Bank, Washington D.C., 1993. 

UNCHS (Habitat) and The World Bank. The Housing Indicators Programme. Report
of the Executive Director (Volume I). UNCHS, Nairobi, 1993.

UNCHS (Habitat). Monitoring the Shelter Sector. Housing Indicators Review.
UNCHS, Nairobi, 1995.

LEAD AGENCY: HABITAT