Spatiotemporal Probabilistic Assessment of Landslide Hazard along Bamenda Mountain Region of ...

432 Pages·2015·27.05 MB·English

Spatiotemporal Probabilistic Assessment of Landslide Hazard
along Bamenda Mountain Region of the Cameroon Volcanic Line

Doctor of Philosophy in Physical Geography

Departamento de Geografia
Department of Geography

ROLAND NGWATUNG AFUNGANG

July 2015

Spatiotemporal Probabilistic Assessment of Landslide Hazard
along Bamenda Mountain Region of the Cameroon Volcanic Line

Thesis supervised by Professor Carlos Valdir de Meneses Bateira
And co-supervised by Professor Roger Ngoufo

Tese orientada pelo Professor Doutor Carlos Valdir de Meneses Bateira
E co-orientada pelo Professor Roger Ngoufo
This dissertation was done under the MUNDUS ACP II Project Sponsored by
the European Commission and Coordinated by the University of Porto.
Esta dissertação foi feita no âmbito do Projecto MUNDUS ACP II financiada
pela Comissão Europeia e Coordenado pela Universidade do Porto

July 2015

DEDICATION
To My Father, Papa Ngwatung Clement Tamasang

&

My Late Mother, Mama Jenetta Masah Ngwatung

Our life is in God's hand [...] “Destiny draws a black ball from the ballot-boxes of those living”.
GUMBEL (1958) calculus of mortality probabilities

July 2015

ACKNOWLEDGEMENTS
This work is realised thanks to a number of people who through their literal, economic,
physical and moral contributions, gave me the necessary means to go through. Many people
more than I can count were instrumental directly or indirectly.

I will as always, begin by thanking the Almighty God “Alfa & Amega” who has kept me
alive and healthy and has given me the capacity to be able to do this work.

Spatial thanks goes to the European Commission and the MUNDUS ACP PROJECT for their
financial support and to the Coordination team including; Barbara Costa, Ana Paiva and Sara
Martins who have supported me all through these years.

I wish to express my sincere gratitude to Pr. Carlos Bateira who is my supervisor for his
knowledge, experience and advice that has guided me all through this project. He laid the
foundation of this work and spent extra time teaching me the techniques that I have used. His
personal touch gave me the confidence that has pushed me to this level

I also thank Pr. Roger Ngoufo who is my co-supervisor for providing the necessary support
that I needed to fulfil the administrative requirements and the materials he gave for field work
which has enrich the quality of this project.

My gratitude goes to Pedro Goncalves who taught me many important techniques in GIS that
I developed and applied during the studies. His assistance during the early days was crucial
and enabled me adapt to the PhD programme at the University of Porto.

My thanks also go to Pr. Antonio Gomes and Pr. José Teixeira for their guidance in
developing the base materials that I needed for the research like the satellite image and the
interpretation of the relief.

I wish to acknowledge the contribution of Pr. Laura Soares and Pr. Antonio Costa for the
assistance they gave me in ArcGIS. They taught me the Logistic regression model which I
applied in the project.

Many thanks to Dr Nkwemo Clement who gave me the thematic maps that I used at the
beginning of this work

My gratitude to Claude Rigobert Kameni, Barbara Costa, Ana Mato, Angela Leitao, Carla
Augusto, Pr. Rio Fernandes and Pr. Tchawa Paul for their efforts in ensuring the signing of
the co-supervision agreement between the University of Porto and University of Yaoundé.

Spatial thanks go to Fr. Paulinus Abose and Ngwatung Calistus for their correction of the
thesis and also to Manuel Teixeira and Djougang Agnes for their translation of the abstract

Very special thanks to my wife, Ritreh Beatrice for taking care of our twin daughters, Larian
and Lorinda during my long absence and to my family, Lawyer Teufack Prisca, Ngewung
Calista, Ngwatung Norbert and Muma Gilbert for their moral support.

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TABLE OF CONTENT
LIST OF TABLES…………………………………………………………………………. .x
LIST OF FIGURES………………………………………………………………………. xv
ABSTRACT……………………………………………………………………………...xxiii
RESUMO……………………………………………………………………………….. xxv
RÉSUMÉ………………………………………………………………………………..xxvii
ACRONYMES AND ABBREVIATIONS………………………………………………xxix

INTRODUCTION ..................................................................................................................... 1
CHAPTER 1: THE STATE OF THE ARTS ........................................................................... 13
1.1. Natural Hazards ............................................................................................................. 13
1.2. Landslide hazard assessment ......................................................................................... 15
1.2.1. Landslides Probability concept ............................................................................... 18
1.2.2. Spatial Susceptibility concept ................................................................................. 19
1.2.2.1. Spatial analysis and modelling......................................................................... 20
1.3. Scale factor and models ......................................................................................... 22
1.3.1. Temporal probability concept ............................................................................. 24
1.4. Differences between landslide hazard and landslide risk .......................................... 26
1.5. Landslide monitoring .................................................................................................... 27
1.6. Landslide Inventory ....................................................................................................... 28
1.7. Slope Mechanisms and slope Instability ....................................................................... 29
1.7.1. Gravity .................................................................................................................... 29
1.7.2. Pore pressure........................................................................................................... 30

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CHAPTER 2: PHYSIOGRAPHY AND ANTHROPOGENIC COMPONENTS OF THE
STUDY AREA ........................................................................................................................ 35
2.1. Location of the study area ............................................................................................. 35
2.2. Physiography of the area ............................................................................................... 38
2.2.1. Relief and Morphology ........................................................................................... 38
2.2.1.1. The Volcanic Mountains .................................................................................. 40
2.2.1.2. Intermediate highlands ..................................................................................... 42
2.2.1.3. The Lowlands................................................................................................... 43
2.2.1.4. Eastern valleys ................................................................................................. 44
2.2.2. Lithology ................................................................................................................ 46
2.2.2.1. Volcanic rocks ................................................................................................. 49
2.2.2.2. Plutonic rocks................................................................................................... 52
2.2.2.3. Metamorphic rocks .......................................................................................... 53
2.2.2.4. Sedimentary rocks ............................................................................................ 54
2.2.3. Superficial formations ............................................................................................ 55
2.2.3.1. Degraded rocky outcrop and gravel ................................................................. 56
2.2.3.2. Talus deposit or Scree ...................................................................................... 56
2.2.3.3. Colluvium deposits .......................................................................................... 58
2.2.3.4. Laterite, Lateritic Clay and boulder clay materials .......................................... 59
2.2.3.5. Clay, volcanic ash, clay sand and silt materials ............................................... 60
2.2.3.6. Alluvial deposits .............................................................................................. 61
2.2.3.7. Anthrosols ........................................................................................................ 62
2.2.4. The drainage system ............................................................................................... 62
2.2.5. Vegetation ............................................................................................................... 64
2.2.6. Climatic condition .................................................................................................. 67
2.3. Land use dynamics .................................................................................................... 70

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