Socioeconomic Analysis of Informal Settlement Growth in Dar es Salaam

139 Pages·2010·3.66 MB·English

Socioeconomic Analysis of Informal Settlement
Growth in Dar es Salaam:

The concept for an agent based model

Gina Young
February, 2010
Socioeconomic Analysis of Informal Settlement Growth
in Dar es Salaam: The concept for an agent based
model

by

Gina Young

Thesis submitted to the International Institute for Geo-information Science and Earth Observation in
partial fulfilment of the requirements for the degree of Master of Science in Geo-information Science
and Earth Observation, Specialisation: Urban Planning and Management

Thesis Assessment Board

Prof.Dr.Ir. M.F.A.M. (Martin) van Maarseveen (Chair)
Dr. J. (Johannes) Flacke
Dr. R.V. (Richard) Sliuzas
Dr. T. (Tatiana) Filatova (External Examiner)

INTERNATIONAL INSTITUTE FOR GEO-INFORMATION SCIENCE AND EARTH OBSERVATION
ENSCHEDE, THE NETHERLANDS
Disclaimer

This document describes work undertaken as part of a programme of study at the International
Institute for Geo-information Science and Earth Observation. All views and opinions expressed
therein remain the sole responsibility of the author, and do not necessarily represent those of the
institute.
Abstract
Dar es Salaam‟s informal settlements are home to 70 – 80 % of the city‟s residents and are
characterized by high housing densities, unstructured road infrastructure and inadequate water,
electricity, and sewerage services. In such an informal settling, predicting land-use change may pose a
challenge for conventional modelling techniques. In this study, empirical evidence was used to
develop the concept for a spatially-explicit agent based model that can later be used to predict land-use
change in an informal settlement in Dar es Salaam. The model incorporates the socio-economic drivers
of development, the biophysical attractive and deterrent forces that affect location decision-making by
households, as well as the effect of the macroeconomic conditions that impact the pace of
development. A short household questionnaire survey and supplemental macroeconomic data were
used to identify agents and determine their behaviour and its exogenous influences. The model concept
was validated by third party individuals for its theoretical and logical correctness. The model is
comprised of two main levels – micro and macro, and is influenced by global parameters, which
should allow for experimentation with the computer-based model, and shows how the settling of
agents at the local level affects the characteristics of the global system (macro-level). The successful
implementation of the model concept lends itself to application to larger geographic locations within
the city.

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Acknowledgements
The production of this thesis would not have been possible without the guidance and support of
friends, relatives, and scholars. I would like to express my deepest gratitude to my supervisors Dr.
Johannes Flacke and Dr. Richard Sliuzas for all the direction they provided, especially with regards to
the structuring and organization of the work and for ensuring my ambitions did not extend beyond my
capabilities (smile). I must also extend a warm thank you to the three experts who reviewed the model
concept, Mr. Friedrich Krebs, Professor Dr. Volker Kreibich, and Ms. Flavia Feitosa (soon to be Dr.
Feitosa). Special thanks to Ms. Feitosa and Dr. Tatiana Filatova for providing helpful hints and critical
reviews that go beyond the field of agent based modelling. Also, a special thank you to Germain
Furaha, Richard Emile, and Dr. Alphonce Kyessi from Ardhi University for all the support they
provided in carrying out the household survey in Hanna Nassif. My appreciation is also for my CEO
Mrs. Beverly Castillo for believing in her staff and for partly granting me the opportunity to be here
under the conditions that I am. Also, thanks to my friends and co-workers in Belize. Thanks to my
parents Yolanda Young and Elgene Young, my sister Esther Silva, my four brothers, and the rest of
my family for your words of encouragement and for believing in me throughout. Thank you to Katrin
Siegler for being my quiet source of inspiration when it mattered most. And last but not least my
friends and lecturers in ITC and PGM department for making this educational experience fun and
rewarding beyond comparison.

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Table of contents
Abstract ................................................................................................................................................... i
Acknowledgements…………………………………………………...………………………………..ii
List of figures………..………………………………………………………..………………….……vii
List of tables.….…………………………………………………………...…………………………viii
Acronyms and Abbreviations …………………………………………………………………….…ix

1. Introduction ..................................................................................................................................... 1
1.1. Background ............................................................................................................................. 1
1.1.1. Definition of informal settlements ................................................................................... 1
1.1.2. Problems associated with informal settlements ............................................................... 1
1.1.3. Population density in Dar es Salaam‟s informal settlements .......................................... 2
1.1.4. Source of urban growth in Dar es Salaam ....................................................................... 2
1.1.5. Predicting spatial change in the urban environment ........................................................ 2
1.2. Hanna Nassif: the case study ................................................................................................... 3
1.3. Research problem .................................................................................................................... 5
1.3.1. Factors affecting growth of informal settlements ............................................................ 5
1.3.2. Economic factors ............................................................................................................. 5
1.3.3. Sources of financial capital for housing .......................................................................... 5
1.3.4. Why ABM for modelling informal settlement growth .................................................... 6
1.4. Research objectives ................................................................................................................. 6
1.4.1. Aim .................................................................................................................................. 6
1.4.2. Objectives ........................................................................................................................ 7
1.5. Research questions .................................................................................................................. 7
1.6. Conceptual framework ............................................................................................................ 8
1.7. Research design ....................................................................................................................... 9
1.8. Theoretical framework .......................................................................................................... 10
1.8.1. The micro-economy ...................................................................................................... 10
1.8.2. The macro-economy ...................................................................................................... 12
1.8.3. Housing adjustment theory ............................................................................................ 15
1.8.4. Complexity theory ......................................................................................................... 16
1.9. Structure of the report ............................................................................................................ 16
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2. Modeling agents: a new approach in predicting urban growth ...................................................... 17
2.1. Agent based models ............................................................................................................... 17
2.2. Building an agent based model .............................................................................................. 17
2.2.1. Agents ............................................................................................................................ 18
2.2.2. The environment ............................................................................................................ 18
2.2.3. Time ............................................................................................................................... 19
2.2.4. Randomness ................................................................................................................... 19
2.2.5. Agent interactions .......................................................................................................... 19
2.2.6. Bounded rationality ....................................................................................................... 20
2.2.7. Learning ......................................................................................................................... 20
2.3. Software environments and programming languages ............................................................ 21
2.3.1. Repast ............................................................................................................................ 21
2.4. Land-use/land cover change ABMs and applications ........................................................... 22
2.5. Spatial planning support systems .......................................................................................... 22
2.6. Modelling informal settlements ............................................................................................. 23
2.7. Definition of a conceptual model .......................................................................................... 24
2.8. Conceptual ABM with examples ........................................................................................... 24
2.8.1. Multi-agent simulation for urban segregation ............................................................... 24
2.9. Empirical basis for ABMs ..................................................................................................... 25
2.9.1. Problems with case studies ............................................................................................ 25
2.9.2. Empirically-informed ABMs ......................................................................................... 26
3. Methodology .................................................................................................................................. 27
3.1. Research structure ................................................................................................................. 27
3.1.1. Document analysis ......................................................................................................... 28
3.1.2. Collection of socioeconomic and macroeconomic data ................................................ 28
3.1.3. Analysis and interpretation of data ................................................................................ 33
3.1.4. Structuring of information into a conceptual model ...................................................... 33
3.1.5. Model validation using subject matter expert interviews .............................................. 33
3.2. Answering the research questions ......................................................................................... 34
4. Micro-level economic activity and residential location decision-making ..................................... 39
4.1. Triggers of housing construction ........................................................................................... 39
4.2. Budget constraints and consumption sets .............................................................................. 40
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4.3. Optimal factors for residential location ................................................................................. 44
4.4. Constraints affecting location choice .................................................................................... 45
4.5. Neighbourhood socioeconomic characteristics ..................................................................... 45
5. Tanzania‟s Macroeconomic Policies, Inflation rate and REER .................................................... 47
5.1. Macroeconomic policy and conditions .................................................................................. 47
5.1.1. 1970-1985: Social policy and inward reform episode ................................................... 47
5.1.2. 1986-1993: Policies for efficiency and growth episode ................................................ 49
5.1.3. 1994-2004: Initiatives to combine growth and social policy episode ........................... 50
5.2. Macroeconomic effects on construction activity ................................................................... 51
6. Model Development ...................................................................................................................... 53
6.1. Household agents and micro-level behaviour ....................................................................... 53
6.1.1. Categorizing agents ....................................................................................................... 53
6.1.2. Triggers of housing construction ................................................................................... 54
6.1.3. Budget constraint ........................................................................................................... 55
6.1.4. Optimal factors for residential location ......................................................................... 59
6.1.5. Constraints affecting residential location ...................................................................... 60
6.1.6. Neighbourhood socioeconomic characteristics ............................................................. 60
6.2. The model concept ................................................................................................................ 61
6.2.1. Model‟s agents .............................................................................................................. 61
6.2.2. Micro level .................................................................................................................... 64
6.2.3. Global parameters .......................................................................................................... 68
6.2.4. Macro level .................................................................................................................... 70
6.2.5. Time............................................................................................................................... 76
6.2.6. Model assumptions ........................................................................................................ 76
6.2.7. Data limitations ............................................................................................................. 76
6.2.8. Requirements for model implementation ...................................................................... 77
6.2.9. Recommended software package .................................................................................. 77
6.3. Validation results ................................................................................................................... 77
6.3.1. Criteria for incorporation of recommendations ............................................................. 78
6.3.2. SME comments and suggestions ................................................................................... 80
6.3.3. The proposed social network ......................................................................................... 82
7. Reflection on methodological approach ........................................................................................ 83
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7.1. Macro-level analysis of development activity ....................................................................... 83
7.2. Conducting field work by remote means and its implications............................................... 83
7.3. Computer programming ........................................................................................................ 84
7.4. Concept overview document ................................................................................................. 84
8. Conclusion and further recommendations ..................................................................................... 85
8.1. Objectives revisited – a summary of findings ....................................................................... 85
8.2. Research adjustments ............................................................................................................ 87
8.3. Future considerations for the model ...................................................................................... 88
8.3.1. Data requirements .......................................................................................................... 88
8.3.2. Expert suggestions not yet incorporated ........................................................................ 89
8.3.3. Model relevance and use ............................................................................................... 89
9. References ..................................................................................................................................... 91
10. Annexes ..................................................................................................................................... 95

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List of figures
Figure 1-1: Hanna Nassif location ........................................................................................................... 4
Figure 1-2: Hanna Nassif boundary features ........................................................................................... 4
Figure 1-3: Conceptual Framework......................................................................................................... 9
Figure 2-1: Environment-Rules-Agent Framework .............................................................................. 20
Figure 2-2: Framework for planning and decision-making process ...................................................... 23
Figure 2-3: MASUS conceptual model ................................................................................................. 25
Figure 2-4: Conceptual model of effects of formal and informal rules on WUAs ................................ 26
Figure 3-1: Operational Plan ................................................................................................................. 29
Figure 5-1: Tanzania inflation rates 1970-2004 .................................................................................... 48
Figure 5-2: Tanzania real effective exchange rates 1969-2005 ............................................................. 49
Figure 6-1: Changes in lot values using REER (adjusted to disregard inflation) .................................. 58
Figure 6-2: Overview of conceptual model ........................................................................................... 62
Figure 6-3: Agent transformation module ............................................................................................. 65
Figure 6-4: Decision-making rules for agent with formal employment ................................................ 67
Figure 6-5: Decision-making rules for agent with self-employment .................................................... 67
Figure 6-6: Modules combined: micro-level behaviour ........................................................................ 68
Figure 6-7: Factor 1: Secondary roads and associated agent welfare .................................................... 71
Figure 6-8: Factor 2: Nearest local market and associated agent welfare ............................................. 72
Figure 6-9: Factor 3: Nearest bus stop and associated agent welfare .................................................... 72
Figure 6-10: Constraint 1: Flood-Prone areas and associated welfare (disutility) ................................ 73
Figure 6-11: Constraint 2: Steep slopes and associated welfare (disutility) .......................................... 73
Figure 6-12: Relative agent utility: agents with formal employment .................................................... 74
Figure 6-13: Relative agent utility: agents with self-employment ........................................................ 74
Figure 6-14: Relative lot price estimation ............................................................................................. 75
Figure 6-15: Plots with proper drainage ................................................................................................ 75
Figure 6-16: Original model overview .................................................................................................. 78
Figure 6-17: Original agent behavioural rules for formally employed tenant agent ............................. 79

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