Worldwide, floods are becoming more intense and unpredictable every year. Communities in developing countries face many barriers to protecting themselves, their homes and their livelihoods from these floods. But a new digital mapping approach, developed by the Zurich Flood Resilience Alliance, is helping people to understand this risk, prepare for floods and protect themselves.
The data gap that undermines resilience
It’s vital for communities to be able to plan for flood events: by identifying safe places to go and by protecting their buildings, livestock, crops and other infrastructure. But in developing countries this planning is made difficult by a lack of accurate information. Without detailed local maps communities don’t know where the risks or safe places are, or where to find resources to support them, like safe shelters, clinics, or safe sources of drinking water. When community maps do exist they are often hand-drawn, inaccurate and useful only to a small number of people.
The Zurich Flood Resilience Alliance (ZFRA) has developed an approach to address this issue: we have been working to combine collaborative digital mapping techniques with community-based mapping methods.
Bringing local knowledge to a global scale
To bridge the data gap in local information we used OpenStreetMap, an emerging open-source platform which is based on contributions from people all around the world: from engineers and humanitarians to mapping enthusiasts. These contributors use aerial photos, GPS and low-tech field maps to give accurate and up-to-date information about their location.
We were able to take the information provided by this new technology and combine it with the local knowledge of volunteer mappers, who compared the digital information with what they could see on the ground.
Using this combination of local and global knowledge, we were able to produce highly detailed information which is more accurate, easier to update and easier share. With this information, more people can be better informed about the risk they face, and so make decisions to keep themselves safe.
Use case: collaborative digital mapping in Nepal
In the Karnali river basin in Nepal – , where flooding last year alone killed 135 people, destroyed 80,000 homes and resulted in an estimated £61 million worth of crops lost – we mapped over 50,000 buildings and 100 km of road thanks to the efforts of a dozen local social workers. They identified agricultural land, community forests, safe shelters and irrigation canals: information which had previously not been captured. This allowed communities to visualise their risks, resources and resilience in a way that was impossible before.
What this means for flood resilience
This approach is an exciting step forward which means that communities will have access to information which is specific to their location and helps them to make decisions based on the risks they face and the resources they have. When we know not just where floods are likely to occur, but where, for example health posts, schools and water pumps are, we can think about what risks the flood itself poses to a community: Will safe drinking water be contaminated? Will people have access to health care? Will children be able to get to school or will the roads be washed away?
This means that communities can plan effectively and take the most effective action to protect themselves from the impacts of flooding, whether it’s raising water pumps so that they are above the anticipated flood water level, relocating supplies or reinforcing roads.
So far, we have applied this approach in Nepal, Peru and Mexico. There is huge potential for this mapping approach to build resilience in hazard-prone communities around the world.