Emergency Event Forecasts 04.02.2022 Tropical Cyclone Batsirai, Madagascar 2022

Intro Cyclone Batsirai made landfall on the east coast of Madagascar over the weekend, displacing over 50,000 people. This is the second major storm to hit the region in two weeks.

Event start

5th January (wind speeds of up to 146mph)

Date of forecast

03.2.2022

Report issuing date

03rd February 2022

Fathom has worked alongside partners to produce a flood risk assessment report, forecasting Cyclone Batsirai’s likely impact on Madagascar.

The tropical storm made landfall on Saturday, causing extreme fluvial and pluvial flooding (in excess of a 1 in 20-year flood event) due to heavy rainfall.

This report has been produced by combining flood layers from Fathom-Global with rainfall forecasts and population datasets to understand the potential exposure to flooding. Terrain analysis was also undertaken on FABDEM to identify populations living in low-lying coastal areas potentially at risk from the storm surge and large waves associated with the cyclone. Researchers use these findings to identify residential areas that are most likely to be affected by flooding. These projections were sent to humanitarian responders on the ground through bulletins provided to the UK Government.

Report Partners

Figure 6. Map showing the locations of districts with the highest percentage of people exposed per district to the return period flood hazard indicated by the reasonable worst-case scenario from GloFAS. Rainfall footprint from ECMWF ensemble forecast produced at 00UTC 4th Feb. This image was produced by the University of Bristol and is underpinned by Fathom’s global dataset.

Batsirai follows from the moderate Tropical Storm Ana, which devastated the area just a week earlier, impacting over 110,000 people in seven regions – with at least 41 fatalities. The Analamanga region was worst affected, with 8927 houses experiencing flooding (ReliefWeb, 27th January 2022).

Forecasts of exposure and impact

This report calculated exposure estimates for flooding of main rivers only. Alongside intense wind (est. 110-120 mph), researchers investigating the event predicted that the region would face a combination of flash, pluvial, fluvial and coastal flooding; with Analamanga, Vatovavy Fitovinany and Atsimo-Atsinann likely to be hardest hit.

The impact of Batsirai

Following the tropical cyclone,  the European Civil Protection and Humanitarian Aid Operations produced a follow-up report, examining the impact of Batsirai on the population of Madagascar. As of the 7th of February, reports indicate at least 20 fatalities, with a further 69,000 people displaced. Several towns sustained severe damage, with a loss of power, water supply and transport routes in Mamamjary City. Localised heavy rainfall is expected to continue.

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