Street-level maps to help plan for floods, disasters

[MANILA] A tool that generates street-level maps of areas with high flood risk promises to aid future disaster planning as climate change increases the frequency and intensity of extreme weather events.

The free onlineWorld Flood Mapping Toolis geared particularly towards countries in the global South, where flood risk maps are rarely available and often out-dated, and where communities are mostvulnerable.

根据World Bank, 89 per cent of people exposed to flood risk live in low- and middle-income countries, which often lack the infrastructure to cope.

The tool, developed by the UN University’s Institute for Water, Environment and Health (UNU-INVEH) with Google and other partners, uses the Google Earth engine combined with satellite (Landsat) data from 1985 onwards. Besides detailed maps of flooding during this period, it has overlays showing population, buildings and land use to help in the planning of resilient developments and infrastructure.

“With limited resources to observe and record previous floods, the global South can use this tool as an alternative to finding out inundation distributions in the past. Those are essential in identifyingvulnerableareas for floods which can be considered in future flood risk management actions,” Hamid Mehmood, a UNU-INWEH remote sensing specialist who led the tool’s development, tellsSciDev.Net.

Mehmood says that the tool is user-friendly and “can easily be handled by even a junior professional with a background in floods to identify the historical flood inundation in any particular location of interest”. Potential users of the tool include forecasting institutions, UN agencies,governmentagencies,researchinstitutions,farmers, real estate developers and insurance companies, he says.

The maps, which can be generated in less than a minute, were validated using documented flooding events in countries including Bangladesh, India, Sri Lanka, Thailand and Mozambique. They are said to have 82 per cent accuracy.

“对任何城市和区域规划部门绘制历史和潜在洪水风险区域的详细图片都是无价的，” UNWEH的Project合作者Duminda Perera在一份声明中说。

The next stage of the tool development — which will be made available for commercial use — is to zoom down to the building level, even incorporating occupancy data.

该工具是最新开发的工具之一climate changeat the granular level. This is critical for countries such as the Marshall Islands that are highly vulnerable to sea-level rise, as well as typhoons and droughts that threaten the territory’s capacity tosupport human habitation.

高级市政Artessa Saldivar-Sali工程师at the World Bank, says that these maps look at three elements: the actual hazards, which factors in both the frequency and intensity vis-à-vis the geography of a given area; exposure, particularly in terms of population distribution; and level of vulnerability.

在马歇尔群岛中，这三个要素是在开发地理信息系统（GIS）地图时的考虑，这些图显示了易受海平面上升和沿海侵蚀以及每个建筑物的风险等威胁的地区。该工具还在联合国提出的不同情况下的因素Intergovernmental Panel on Climate Changewhich vary based on projected carbon emissions.

Video credit:World Bank.

“[With maps], it’s easier to see the bigger picture,” Saldivar-Sali says. “It serves as an illustrative tool to compare different scenarios.” The maps help governments better understand the extent of their vulnerability so they can make climate adaptation plans for the next 100 years.

Besides using the maps as tools for local planning, the Marshall Islands is also set to use it in the upcomingCOP26to act more decisively in response to the threats posed by climate change.

In the case of theInternational Federation of Red Cross and Red Crescent Societies,GIS地图不仅用于告知策略和政策but also to determine humanitarian support in areas that have or are projected to experience severe climate extremes. GIS maps are used throughout thedisastermanagement cycle, says Madhab Uprety, who is technical adviser at theRed Cross Red Crescent Climate Centre在加德满都。

“Climate change is also a humanitarian problem and we can’t separate it, so we need to factor how we can adapt to climate change in the coming years and how we can adapt to it in our operational systems,” Uprety says.

“Climate change is also a humanitarian problem and we can’t separate it, so we need to factor how we can adapt to climate change in the coming years and how we can adapt to it in our operational systems”

Madhab Uprety, Red Cross Red Crescent Climate Centre

Granular maps, says Uprety, make it easier to see the direct impact of climate risks and hazards. “Downscaling projections to the local context and coming up with an impact scenario, or potential scenarios on how certain sectors can be affected, such as agricultural and medical, enables us to come up with a viable and appreciable response.”

Uprety, however, acknowledges that tools such as GIS and other mapping tools that are paid and licensed software may be less suitable and sustainable to developing countries that have limited resources. He stresses the need for the adoption of open-source tools and platforms to avoid running costs.

Peeranan Towashiraporn, director of the geospatial information department of theAsian Disaster Preparedness Centre,says that existing tools can be tapped by countries that are unable to generate their own maps. He says there are mechanisms such asSentinel Asiaand theInternational Charter Space and Major Disasters允许国家卫星pro的访问ducts such as flood maps. Other international organisations such as the UN世界粮食计划, and the UNSatellite Centreare also making disaster maps.

Uprety says that tech giants such as Google and Facebook are now showing interest in developing maps of areas affected by climate extremes like floods. He adds that the possibility of acquiring information in real-time will help humanitarian responders understand what is happening on the ground.

This piece was produced by SciDev.Net’s Asia & Pacific desk.