A COMPARATIVE STUDY OF LANDSLIDES AND GEOHAZARD ...

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CC : Canopy Cover ABBREVIATIONS <strong>AND</strong> ACRONYMS CURE : Conservation Unit for the Rehabilitation of the Environment Dbh : Diameter at Breast Height DEM : Digital Elevation Model Dsh : Diameter Stump Height ETM : Earth Elevation Model FGD : Focus Group Discussion FRIM : Forestry Research Institute of Malawi GoM : Government of Malawi GPS : Global Positioning System GTZ : German Technical Cooperation H : Height IGAs : Income Generating Activities ITCZ : Inter Tropical Convergence Zone M1 : Main Road MASAF: Malawi Social Action Fund MEET : Malawi Environmental Endowment Trust MWD : Mean Weight Diameter NEAP : National Environmental Action Plan NEP : National Environmental Policy NGOs : Non Governmental Organisations NRA : National Roads Authority NSO : National Statistical Office VBCA : Vunguvungu Banga Catchment Areas xxvi
1.1 Background CHAPTER ONE INTRODUCTION Landslides are defined as the mass movement of rocks, debris or earth along a sliding plane. They are characterised by almost permanent contact between the moving masses and sliding plane (Butler, 1976; Crozier, 1984; and Smith, 1996). Landslides cause substantial economic, human and environmental losses throughout the world. Examples of devastating landslides at a global scale include the 1972 Calabria landslide in Italy, the 1970 Hauscaran landslide in Peru (McCall, 1992), the 1966 Aberfan landslide in Wales, and the 1985 Armero landslide in Colombia (Alexander, 1993). It is estimated that in 1998, 180,000 avalanches, landslides, and debris flow in different scales occurred in China, estimated at 3 billion dollars worth of direct economic losses (Huabin et al., 2005). In Africa, landslides are not new phenomena. They have been reported in Cameroon, Kenya, Uganda, Rwanda, Tanzania, and Ethiopia (Rapp et al., 1972; Ngecu and Ichang’i, 1989; Moeyersons, 1988, 1989a and b; Davies, 1996; Westerberg and Christiansson, 1998; Ayalew, 1999; Ngecu and Mathu, 1999; Westerberg, 1999; Inganga et al., 2001; Muwanga et al., 2001; Nyssen et al., 2003; and Knapen et al., 2006). Although the East African highlands are a very heterogeneous region in terms of physiography, geomorphology and rainfall (Knapen et al., 2006), they have a high vulnerability to slope instability in common. The high annual rainfall, high weathering rates, deforestation and slope material with a low shear resistance or high clay content are often considered the main preconditions for landslides (Knapen et al., 2006). A number of landslide events have occurred in Malawi and the causes are similar to those in the East African region (Cheyo, 1999; Mwenelupembe, 1999; and Msilimba and Holmes, 2005). Examples include the 1946 Zomba Mountain landslide (Cheyo, 1999), the 1991 Phalombe Landslide (Poschinger et al., 1998) and the 1997 Banga Landslide (Msilimba, 2002; and Msilimba and Holmes, 2005). A summary of known landslides that have occurred in Malawi from 1946 to 2000 is given by Msilimba (2002), Msilimba and Holmes (2005) and in Table 4.1 p.66. 1
Page 1 and 2: A COMPARATIVE STUDY OF LANDSLIDES A
Page 3 and 4: DECLARATION I declare that this the
Page 5 and 6: It was found that 131 landslides ha
Page 7 and 8: OPSOMMING In 2003 het ‘n aantal g
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: Table 8.10 : Repetition of Landslid
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
Page 61 and 62: 2.2.3.3 Geology The rocks of the ca
Page 63 and 64: CHAPTER THREE LANDSLIDES: CLASSIFIC
Page 65 and 66: 1982). Topples have been observed t
Page 67 and 68: 3.4 Classification of Slopes In slo
Page 69 and 70: angle and hence greater values of g
Page 71 and 72: 3.6.5 Implications of Joints and Ro
Page 73 and 74: movement (Crozier, 1984). Preparato
Page 75 and 76: 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
Page 105 and 106:
5.11 Soil Analyses Soil samples wer
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5.11.1.4 Determination of Bulk Dens
Page 109 and 110:
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
Page 139 and 140:
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
Page 195 and 196:
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
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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
Page 221 and 222:
continued destruction of the vegeta
Page 223 and 224:
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
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stabilisation can also be achieved
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knowledge on landslides in Malawi a
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Badshah, A.: 1994, The Mega-Cities;
Page 237 and 238:
Briggs, J. Badri, M. and Mekki, M.:
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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
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Mwafongo, K.W.M.: 1996, Rural Devel
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Pitty, A.F.: 1984, Geography and So
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Tsukamoto, Y. and Kusakabe, O.: 198
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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,
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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
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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
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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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