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Participatory 3D mapping: A tool for disaster risk reduction

23 May 2012

Natural disasters continue to claim lives and devastate families, particularly the global South. The poor are most vulnerable as they typically live in the most hazardous locations. However, this social and geographical reality also compounds the problems, because of the gaps that exists between planners and the poor. The two groups speak different languages, have different understandings about the problems and what to do. Bridging such gaps could be a way to build greater resilience to extreme environmental events. Participatory 3 dimensional mapping is a technique that promises to do this.

The practice of participatory surveys and data collection has grown over the past two decades. By collecting new information about themselves and the places they live in poor and marginalised groups gain new skills, knowledge and confidence and can present evidence to press their needs to the powers that be. This is a field where the global North can learn from what has been happening in poorer parts of the poorer countries. Participatory 3D mapping (P3DM) is part of this pro-poor practice.

Community-based Disaster Risk Reduction

The value of community-based approaches to disaster risk reduction (DRR) is likely to grow in the face of more volatile climatic conditions and the limited capacities of governments to respond to threats. Participatory mapping is already an established part of community-based DRR. It enables local residents to draw on their past experiences to identify vulnerable areas and to focus thinking on risk reduction measures.

Meanwhile the growing sophistication of Geographical Information Systems is also being tapped by some communities, though there are obvious problems of access and know-how. In addition, the person introducing and using GIS is likely to then be in a very powerful position, and well placed to set the agenda and benefit from credibility with officials.

So how does P3DM work? Basically you build a 3 dimensional relief map. To do this you can use cheap, locally available materials, such as cardboard. You cut layers to a scaled thickness to represent verticality. These real relief maps can then be overlain with layers of information and used as a focus for new information collection and discussions.

An example from the Philippines

An article by Cadag and Gaillard, published in Area recently, describes the use of P3DM in the Philippines. Masantol is a municipality in a delta area. As well as flooding, there are tsunamis, earthquakes, storm surges and cyclones. As if that was not enough, extraction of groundwater is also resulting in land subsidence. There are 6 villages.
After a long period of building a relationship with the people, the P3DM project began in August 2008, ran for a year and cost less than US$1000.
The facilitators prepared a 1:2700 base map, using GIS and official maps. Different coloured push-pins were chosen to denote houses, schools, health centres, etc. Yarn represented linear features and different coloured paint different land uses. The people were able to map the houses where the most vulnerable members of their communities lived, and also the locations of boats and similar assets that could be used in the event of an emergency.

A critical stage of the work was the combination on the relief map of people’s own local knowledge of areas at risk (e.g. weak points along dykes), with scientific data about hazards, and information provided by government officials. In this way the capacity to anticipate and respond was increased. The researchers argue that this made disaster risk assessment, “faster, more efficient and more sustainable at community level. “

Action planning

The assessment had led to agreement that one of the villages was especially vulnerable. That village then became the focus for an action planning activity. A community-based DDR plan was drawn up through working closely with village and municipal governments. A 1:500 map of the village was built for this purpose.
Bamboo posts were painted and installed to provide early warning of rising waters. Warning and evacuation plans were formed for different types of hazards. The emergency plan was printed on a large tarpaulin sheet and hung in front of the village hall so everybody could see it.

A valuable tool

Cadag and Gaillard concluded that P3DM is a powerful tool that can be used by communities to appraise the risks of disasters in their environment. Just as important, it makes local knowledge credible to officials, and thus allows for the combination of local and scientific knowledge.

Preparing for, and coping, with disasters represents one of the greatest challenges globally to this generation of planners. We need to be alert to techniques like this that can make a difference and underpin the action planning process that is so much more relevant to the needs of the poor than the static, outdated master plans that so often represent the practice of planning in rapidly urbanising countries.

(Photo J.C Gaillard)

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