A COMPARATIVE STUDY OF LANDSLIDES AND GEOHAZARD ...

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hydro-geological assessment of the areas; development of landslides predictive models for Malawi; and the development of a landslide early warning system. Msilimba Golden G.C University of the Free State November, 2007 Keywords Malawi; Landslides; Geohazard; Mitigation; Assessment; Traditional Knowledge; Gender; Rockfalls; Debris flows; Rotational; Translational. vi
OPSOMMING In 2003 het ‘n aantal grondstortings voorgekom in die Ntchenachena en Chiweta gebiede van die Rumphi distrik in noord Malawi, en in die Livilivi/Mvai opvanggebiede van die Ntcheu distrik in sentraal Malawi. Die grondstortings het merkbare skade aan gewasse, landbougrond, lewende hawe en infrastruktuur aangerig. Erger nog, dit het die dood van vier persone veroorsaak. Die hoë digtheid van die voorkoms van grondstortings dui op die onstabiliteit van hange in hierdie gebeide aan. In die lig van hierdie grondstortings is hierdie studie daarop gerig om die stabiliteit van die hange in die gebiede te bepaal. In die studie word grondstortings gekarteer en waargenome gebeurtenisse geklassifiseer; oorsake en bydraende faktore word evalueer; sosio-ekonomiese en omgewingsimpakte van die gebeure word evalueer; tradisionele kennis, gelowe en mense se persepsies aangaande grondstortings word ondersoek; hanteringstrategieë word bepaal en versagting van grondstortings as gevare word ontwikkel. Hierdie studie sluit ‘n inventaris van alle waargenome grondstortings in. Die terrein se fisiese eienskappe wat hang onstabiliteit beïnvloed het, is gemeet. Die eienskappe wat aangeteken is, sluit in hanglengte, helling, aspekte en hoogte, en kanaal dimensies. Grondstortings is geklassifiseer op grond van die tipe beweging, die graad van stabilisering, ouderdom en die materiaal betrokke in die storting. Grondmonsters is versamel deur van kern- en kluitmonster metodes gebruik te maak en is getoets vir plastisiteitsgrens, vloeigrens, plastisiteitsindeks, bulkdigtheid, hidrouliese geleidingsvermoë, aggregaatstabiliteit en partikelgrootte. Strukturele rotsswakhede is ook gemeet. Plantegroeidata is versamel deur gebruik te maak van die kwadrant metode. Dit is ontleed vir gemiddelde deursnitte vii
Page 1 and 2: A COMPARATIVE STUDY OF LANDSLIDES A
Page 3 and 4: DECLARATION I declare that this the
Page 5: It was found that 131 landslides ha
Page 9 and 10: verminder, gemeenskapsdeelname in n
Page 11 and 12: ACKNOWLEDGEMENTS I would like to ex
Page 13 and 14: us all that determination and commi
Page 15 and 16: 2.2.2.5 Climate 31 2.2.2.6 Vegetati
Page 17 and 18: 5.10.1.3 Crown Width 78 5.10.1.4 Ve
Page 19 and 20: 8.5 Cross Tabulation of Perceived C
Page 21 and 22: LIST OF FIGURES Figure 2.1a : The P
Page 23 and 24: Ntchenachena Area by goats, contrib
Page 25 and 26: Table 8.10 : Repetition of Landslid
Page 27 and 28: 1.1 Background CHAPTER ONE INTRODUC
Page 29 and 30: these factors. It also aimed at est
Page 31 and 32: Msilimba and Holmes, 2005). Norther
Page 33 and 34: 1.7 Organisation of the Thesis This
Page 35 and 36: Figure 2.1a: The Physiography of th
Page 37 and 38: To these divisions, may be added th
Page 39 and 40: Figure 2.2: Erosion surfaces of Mal
Page 41 and 42: Figure 2.3: The Geology of Malawi.
Page 43 and 44: Figure 2.4: Land use and land cover
Page 45 and 46: seasonal maximum and minimum temper
Page 47 and 48: Figure 2.5: Location of the Ntchena
Page 49 and 50: Figure 2.6: Part of the Ntchenachen
Page 51 and 52: 2.2.1.5 Climate The temperatures on
Page 53 and 54: Figure 2.10: Tobacco curing shed in
Page 55 and 56: sequence includes beds of modular l
Page 57 and 58:
2.2.2.3 Topography The Chiweta Area
Page 59 and 60:
2.2.3 Mvai/Livilivi Catchment Areas
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2.2.3.3 Geology The rocks of the ca
Page 63 and 64:
CHAPTER THREE LANDSLIDES: CLASSIFIC
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1982). Topples have been observed t
Page 67 and 68:
3.4 Classification of Slopes In slo
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angle and hence greater values of g
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3.6.5 Implications of Joints and Ro
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movement (Crozier, 1984). Preparato
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containing a high percentage of cla
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largest landslides occur most frequ
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Mshali, 1989; Gondwe and Govati, 19
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avalanche Abefan, Wales 21/9/1966 F
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environmental problems (Taun, 1974)
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Malawi, emphasise only the causes.
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short of the identification and con
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Ingaga et al., 2001; Msilimba, 2002
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CHAPTER FOUR LANDSLIDES INVENTORY I
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4.2 Analysis of the Previous Studie
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4.4 Proposed Mitigation Measures fr
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CHAPTER FIVE METHODOLOGY The curren
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Ground reference data was acquired
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density of drainage network, and th
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weathered. Samples were collected f
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5.11 Soil Analyses Soil samples wer
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5.11.1.4 Determination of Bulk Dens
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5.11.1.8 Determination of Liquid Li
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The questionnaire was coded for eas
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and impacts of landslides and seeki
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CHAPTER SIX LANDSLIDE DISTRIBUTION,
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Ntcheu Livilivi Chiweta Lutowo 8c 2
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distribution was evenly among SE (3
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Figure 6.4: Mapped landslides in th
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6.3 Classification of the Mapped La
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Table 6.2: Landslides Classificatio
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Table 6.4: The Determination of the
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6.6 Discussion of the Landslides Ma
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Catchment where the rocks hang loos
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and the 1991 Phalombe landslides (G
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In Ntcheu District, the Livilivi/Mv
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Figure 6.12: Position where landsli
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CHAPTER SEVEN ANALYSIS OF THE LANDS
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constructed, in the Ntchenachena Ar
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Chiweta Livilivi Mvai 3 53.29± 10.
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was confirmed by ANOVA test (p=0.00
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Table 7.9: Results of the Analysis
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Table 7.11: Medium/Fine Sand Test R
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Mvai 55.8±6. 41 1 69.2±9. 34 67.8
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Rainfall (mm) 200 150 100 50 0 Dail
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The landslides of the Ntchenachena
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customary land tenure. Most of the
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Hoek’s critical angle for sliding
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esistance for these soils was proba
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acting as a lubricant (Crozier, 198
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cover of grasses and shrubs, record
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with major structural rock weakness
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disturbance caused by deforestation
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Figures 7.14 and 7.15). This has pa
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Figure 7.16: Highly weathered Chiwe
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CHAPTER EIGHT TRADITIONAL KNOWLEDGE
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majority of the respondents had att
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Table 8.3: Types of Housing Distric
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Table 8.6: Knowledge of Past Landsl
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Table 8.9: Weather Conditions Befor
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Table 8.11: Level of Education and
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Table 8.13B: Age of Respondents and
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with tertiary education were observ
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construction during the rainy seaso
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Figure 8.3: Degraded agricultural l
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out an assessment of the damage. La
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2005). The results from these studi
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Table 8.23: Responsibility for Slop
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This study, therefore, realises tha
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wanted the NGOs/Government to rehab
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difficult and also reduces the area
Page 207 and 208:
8.17.1.4 Government Policy The majo
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noise from drums. These spirits are
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CHAPTER NINE ANALYSIS OF LANDSLIDE
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true for the entire East Africa reg
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This explains why the majority of l
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damage from landslides. In areas wh
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embankments may result in a build u
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continued destruction of the vegeta
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Furthermore, future research should
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esults have been encouraging (Mikke
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landslides. Gender perceptions towa
Page 229 and 230:
The destruction of vegetation in al
Page 231 and 232:
stabilisation can also be achieved
Page 233 and 234:
knowledge on landslides in Malawi a
Page 235 and 236:
Badshah, A.: 1994, The Mega-Cities;
Page 237 and 238:
Briggs, J. Badri, M. and Mekki, M.:
Page 239 and 240:
Cooke, R.U and Doornkamp, J.C.: 199
Page 241 and 242:
Fairhead, J. and Scoones, I.: 2005,
Page 243 and 244:
Harlford, S. and Leonard, P.: 2001,
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Jibson, R.W. and Keefer, D.K.: 1968
Page 247 and 248:
Ludman, A. and Koch, N.I.: 1982, Ph
Page 249 and 250:
Mwafongo, K.W.M.: 1996, Rural Devel
Page 251 and 252:
Pitty, A.F.: 1984, Geography and So
Page 253 and 254:
Tsukamoto, Y. and Kusakabe, O.: 198
Page 255 and 256:
Yamamuro, J.A and Lade, P.V.: 1998,
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v = volume of slope material involv
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APPENDIX 3: HOUSEHOLD QUESTIONNAIRE
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5. Are you employed? Yes (proceed t
Page 263 and 264:
15. What are the traditional belief
Page 265 and 266:
26. Which crops were affected by th
Page 267 and 268:
36. What was the most important for
Page 269 and 270:
APPENDIX 4: DISTRICT COMMISSIONERS,
Page 271 and 272:
13 How long does it take for inform
Page 273 and 274:
6. How far have you gone with lands
Page 275 and 276:
APPENDIX 6: MULTIPLE COMPARISON TES
Page 277 and 278:
Page 279 and 280:
Page 281 and 282:
APPENDIX 9: TESTS FOR THE EQUALITY
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Hydraulic conductivity cm/hr (>100
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Litowo 8 Pit 9 0615288 8819034 1445
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Mvai 2 Pit 8 0675274 8355428 1379 M
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RAINFALL DATA FOR MVAI/LIVILIVI FRO
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PIT 3 LUT 3 0-100 69..80 34.31 35.4
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KASFOR PIT 1 KASFOR >100 43.06 30.9
Page 295 and 296:
PIT 4 CHIKWE 0-100 81.42 43.45 37.9
Page 297 and 298:
PIT 5 MVAI 1 0-100 51.99 36.07 15.9
Page 299 and 300:
NTCHEU FIELD DATA APPENDIX 15: RESU
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Mchenje 167 130 5.7 4.1 Shallow ro
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CHIWETA U1-11 Dsh (mm) Dbh (mm) H (
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AVERAGE 125 93 5.5 3.6 LITOWO 1a-3
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LITOWO 7a-u Dsh (mm) Dbh (mm) Mnthu
Page 309:
Mnthunu 50 Chi 1l 0615438 8819106 1
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A COMPARATIVE STUDY OF LANDSLIDES AND GEOHAZARD ...

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