A COMPARATIVE STUDY OF LANDSLIDES AND GEOHAZARD ...

ABSTRACT
In 2003, a number of landslides occurred in the Ntchenachena and the Chiweta
Areas of the Rumphi District in Northern Malawi, and in the Livilivi/Mvai
Catchments of Ntcheu District in Central Malawi. The landslide events caused
significant damage to crops, farmland, livestock and infrastructure. Worse still,
they caused the death of four people. The high density of landslides
occurrences suggested instability of the slopes of these areas.
In light of these landslides, this study set out to assess the slope stability status of
the areas. The study addressed landslide mapping and classification of observed
events; assessment of the causes and contributing factors; assessment of the
socio-economic and environmental impacts of the events; exploration of
traditional knowledge, beliefs and peoples perceptions surrounding landslides;
determination of the coping strategies; and development of mitigations to
landslides as geo-hazards.
This study involved a landslide inventory of all observed events. The physical
characteristics of the terrain influencing slope instability were measured. The
characteristics recorded included slope length, angles, aspect and altitude, and
channel dimensions. Landslides were classified based on the type of movement,
degree of stabilisation, and age, and materials involved in the movement. Soil
samples were collected, using core and clod sampling methods and were
tested for plastic limit, liquid limit, plasticity index, bulk density, hydraulic
conductivity, aggregate stability, and particle sizes. Structural rock weaknesses
were also measured. Vegetation data was collected, using the quadrant
method and was analysed for average diameters at stump and breast height,
canopy cover, and height. Questionnaires/surveys were used to assess local
knowledge and perceptions towards landslides. A SPSS statistical package was
used to analyse both social and physical data.
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