MoSSiaC

MoSSaiC: Management of Slope Stability in Communities

Contacts: Prof. Malcolm Anderson and Dr. Liz Holcombe
External site: www.mossaic.org

Introduction

The MoSSaiC programme seeks to reduce landslide risk affecting communities and infrastructure. We work with community groups and government agencies to deliver low-cost landslide risk reduction measures, and to develop sustainable strategies for slope stability management.

Our goals are to:

Landslides in the tropics

Tropical regions are especially susceptible to landslides due to high intensity and high duration rainfall levels; the rapid rate of weathering and the deep soils that result (often on steep slopes of volcanic origin); and the incidence of seismic activity. In tropical regions rainfall has been identified as the main landslide trigger. Preliminary evidence suggests that climate change could cause more frequent and intense rainfall in tropical regions such as the Caribbean and Latin America, thus increasing the probability of landslides.

Development and landslide risk

Slopes can become more susceptible to landslides through human activities such as earthworks (cuts and fills), road and building construction, and agriculture, all of which affect slope geometry, vegetation cover and surface-water or groundwater regime.

How MoSSaiC works:

  1. Team-building

    • MoSSaiC Management Committee + Funding Agencies
    • Community development agencies, technical + field teams
    • Community members + local contractors
    • MoSSaiC directors, Prof. Anderson + Dr Holcombe: directing the MoSSaiC programme, providing technical input, R&D
  2. Interactive learning

    MoSSaiC has evolved through ongoing dialogue and interaction with people in Saint Lucia. We have had the opportunity to develop ideas on the ground with community members, local contractors and government agencies. As MoSSaiC expands, the community continues to be a vital place of learning and training for all involved.

  3. Application of cutting-edge science

    The landslide risk reduction measures designed for each community are based on detailed mapping - to which all community members contribute - and scientific rationale. Site monitoring, soil testing and slope stability modeling enable the team to identify the underlying stability mechanism, and determine the appropriate solution. The unique approach of MoSSaiC combines local 'on-the-ground' knowledge of the risk with cutting-edge research techniques.

  4. Implementation of low-cost landslide risk reduction measures

    In many cases the landslide trigger identified by the mapping-modelling process is the saturation of the slope by rainfall and household water. If this surface water can be captured and removed from the slope, the landslide risk can be reduced. Thus, the MoSSaiC approach is based on the design and construction of slope drains and household drains, and the connection of roof guttering and water tanks. Other needs are often tackled along the way: physical needs such as water supply and hurricane proofing; and social needs such as the involvement and employment of community members. These measures involve a significantly lower cost than that of heavy slope engineering or community relocation.

Selected outcomes in Saint Lucia 2004-06

CategoryIndicatorImpact
Community Community employment

496 person-weeks employment for community members
Generated ideas from community members for formation of specialist drainage construction companies

Community construction partnerships Residents share with Government in terms of design, construction and cost
Water supply continuity 450-gallon water tanks supplied to most deserving residents
Physical Landslide hazard resilience Stable against 1:1~1:4 year storm
Improved rainfall management Roof guttering and drain connections yield >20% reduction in rainfall infiltrating slope
Economic Project expenditure profile 93% of all funds spent on materials and community labour
Public Awareness Media recognition Saint Lucia TV: 30 minute MoSSaiC documentary commissioned
  Saint Lucia TV and Radio: interviews and news coverage
Project scope Households ~ 400
Residents ~ 2000
Cost per person ~ US$250
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