Community of Practitioners' Site

About Mossaic

“We're still to some extent sleepwalking our way into disasters for the future which we know are going to happen, and not enough is being done to mitigate the damage”. (Holmes, Under-Secretary-General for Humanitarian Affairs, UNEP. 2009).


MoSSaiC: Management of Slope Stability in Communities – is an integrated method for engaging policy makers, project managers, practitioners and vulnerable communities in reducing urban landslide risk in developing countries. Whilst the method may be helpful in that context, it is not of itself a decision making tool.

Many areas of the world are at risk from landslides and their consequences; rainfall-triggered landslides particularly affect developing countries in the tropics. Rapid urbanization, and the associated growth of unauthorized and densely populated communities in hazardous locations (such as steep slopes), are powerful drivers in a cycle of disaster risk accumulation. There is recognition that on-the-ground implementation of landslide risk reduction measures is lacking – we are doing too little, too late.

MoSSaiC started with the concept of combining research, policy and humanitarian interests to address rainfall-triggered landslide hazard through the community-based implementation of surface water management measures in vulnerable urban communities. The vision was to lay sustainable foundations for community-based landslide risk reduction.

 This vision was driven by the following premises:

  • Disaster Risk Mitigation Pays, and investment in reducing rainfall-triggered landslide hazards in vulnerable communities can often be justified
  • Engaging existing Government expertise for implementing risk reduction measures can build capacity, embed good practice and change policy  
  • Ensuring community engagement from start to finish can establish ownership of solutions

To achieve the vision and demonstrate the validity of these premises three foundations needed to be established: the scientific basis, the community base and the evidence base for landslide risk reduction in this setting.

First, from a scientific standpoint it could be seen that the root causes of many landslides in urban communities were aggravated by human activities, and that they could be addressed in relatively simple and practical ways. The most common situation we observed was the probable impact of poor drainage on slope stability. This could often be remedied through the construction of a strategically aligned network of surface drains. Intercepting and conveying surface water runoff, household grey water and roof-runoff to ravines and main drains would significantly improve the stability of slopes in weathered material..

Second, community residents have a detailed knowledge of the slopes in their immediate vicinity – where there have been minor landslides, where that water runs, how the topography and vegetation have been changed. This is frequently the scale at which landslide triggering processes operate and the scale at which solutions can be found. Vulnerable communities are also where there is the greatest need for short-term employment (in constructing mitigation measures), ownership of such projects, and for embedding good slope management practices in the future. We were equally convinced that governments had sufficient technical and managerial skills that could be harnessed to design and deliver appropriate landslide risk reduction measures in communities. By creating a cross-disciplinary management unit from such a skill-base it would be possible to embed MoSSaiC in government practice and policy.

Third, an ‘evidence base’ for the effectiveness of such targeted landslide risk reduction measures was needed. We started small – with a pilot intervention in one community, a catalytic advocate in Government, and a small team of in-house project managers and practitioners. On the evidence of its success, further Government funding and demand for more interventions followed. This evidence was in the form of the finished works, the improved stability of slopes, the endorsement and ownership of the project by the community, and the demonstration of the combined skills of the government team. Savings of losses to the community, and savings of cost to government were also estimated. Decision-makers require such evidence in order to endorse expenditure on landslide risk reduction, and to adopt ex-ante policies.