Tropical cyclones impact assessment in Madagascar in 2022
A rapid geospatial assessment by FAO following tropical cyclones in Madagascar using the administrative units’ data from the SALB programme
Climate change is increasing the frequency, intensity, spatial extent, duration and timing of adverse weather and climate events in all areas of the world, including tropical cyclones and heavy rainfall. Storms and floods are accounted for top two disaster events in last forty years and the total events have doubled in 2000-2019, compared to 1980-1999 as reported by the United Nations Disaster Risk Reduction (UNDRR). This claims approximately 1.23 million lives, an average of 60,000 per annum, and affected a total of over 4 billion people, and approximately US$ 2.97 trillion in economic losses worldwide.
Madagascar is one of the countries most exposed to cyclones in Africa and is extremely vulnerable to climate change. Frequent natural disasters and locust threats negatively affect households’ livelihoods, pushing thousands of people into poverty and hunger. These led the loss of nearly $61 million in food crops, $78 million in cash crops, and $1.5 million in livestock across the Grand Sud-Est from January to April, 2022, according to the Food and Agricultural Organization (FAO) .
In 2022, Madagascar has been impacted by a series of tropical storms and cyclones named Ana, Batsirai, Emnati, and Gombe from late January to early March. These severe tropical storms and cyclones caused deadly floods affecting people’s home and agriculture causing evacuation and food shortages.
The FAO in collaboration with the Ministry of Agriculture and Livestock, undertook a rapid geospatial assessment on the impacts of storms and cyclones on crops and exposure of the rural people using earth observation to evaluate priority districts. This assessment addresses the country’s challenges to achieve the Sustainable Development Goals 2 and 13 [1] , and Sendai Framework for Disaster Risk Reduction 2015-2030 [2] .
The evaluation and analysis on croplands and flood extent was performed using Earth observation data, and the common geographies from the SALB programme were used for furthering the analysis and its overview. The readily available and accessible SALB dataset, sourced from the responsible national office, the Institut Géographique et Hydrographique National (Foiben-Taosarintanin'I Madagasikara), were used to extract, aggregate, and visualize the results, and inform the response at district (Faritra) levels.
Following recent flooding in Madagascar United Nations Second Administrative Level Boundaries (UNSALB) boundary data were used to extract and integrate data at the regional and district levels, visualize the results, and inform the response at the national and district levels.
The rapid geospatial assessment was undertaken to understand the impacts from cyclones and storms for the period January to March 2022, to gain insight at the sub-national level for regions and districts with diverse sourced and typed data. This presented rainfall patterns, flood extent, wind track, cropland inundation, population exposure and the impact of agricultural and livelihood by provinces and district such as for flooded cropland, population exposure. Results, methods, and findings in the form of maps and tables by administrative units can be found in the full report prepared by the Geospatial Unit at FAO’s Land and Water Division (NSL). Available global products were used during the assessment to identify priority areas to conduct high resolution assessment at 10m for the area of interest (AOI).
Flood impact assessment
The analysis based on Visible Infrared Imaging Radiometer Suite (VIIRS) was prepared to provide a regional overview of the floods for the period 1 January - 15 March 2022. The full report contains detailed analysis prepared for this assessment based on Sentinel 1 and Sentinel 2 data for the eastern Madagascar where important croplands are located.
Total cropland
The analysis based on European Space Agency (ESA) WorldCover 2020 at 10m resolution was aggregated using SALB data to show the total cropland area, in hectare (ha), for each district (Faritra). A detailed cropland map and a rice map were prepared using Sentinel 1 and 2 (10m) for the six eastern districts and are available in the full report.
Cropland impact assessment
Assessments for impacted cropland for each AOI were conducted for the respective identified areas. The impact on cropland was calculated using the land cover from WorldCover by ESA at 10 m spatial resolution. Flooded crop was identified as inundated cropland area. Zonal statistics were extracted based on the data from the SALB programme and HDX. Analysis on inundated rice for the six eastern districts are available in the full report.
Exposure of population to flooded cropland
Due to the limitations in the data, a vulnerability assessment for the population exposed to floods was conducted. This considers the percentage of flood extent and the population density by administrative levels. It is assumed that the more people surrounded by flooded areas, the greater the vulnerability. This vulnerability assessment does not consider cropland information considering that nomadic pastoralism can also be affected by floods.
Use the slider in the map below to compare flooding for the first quarter of 2022 with the flooded cropland impact assessment.
The analysis and report by FAO shows the importance of how common geographies, and the work of the SALB programme at making them available, help to identify sub-national areas of impact and priorities for decision-makers to take action. Indeed, using authoritative and standardized administrative unit data can harmonize data analysis, bring consistent approach, and further support humanitarian action for improved recovery programme and informed decision on agricultural development. As part of the analysis, the FAO details further its analysis for six districts of the east of Madagascar.
Readily accessible, interoperable and global data and information on subnational units, or common geographies, as collected in the context of the SALB programme are key for better decisions, stronger support to people and planet and to monitor the Sustainable Development Goals. During disasters, common geographies serve as a fundamental data building block, in addition to live analysis, for the identification of priority districts and areas to target emergency response and long-term program for development.
The boundaries and names shown and the designations used on this map do not imply official endorsement or acceptance by the United Nations
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