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Cred Crunch Newsletter, Issue No. 53 (December 2018) - Flash Floods: Sharing of field experience - Kerala

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In August 2018, the state of Kerala in India was hit by severe flash floods, which carried heavy human and economic consequences. Flash floods are a particular type of flood disasters, characterized by their rapid onset and potential for infrastructure destruction. In this issue, we discuss flash floods and their global importance, and we present a field mission to Kerala undertaken by the CRED Team in partnership with the Indian NGO Doctors For You.

(Flash) Flood profile of India and Kerala

The state of Kerala, in South India, has been affected by 14 floods since 2000 (Fig.A).When looking deeper into EM-DAT data for floods in India (2000-2017), we found that flash floods have a more important human impact than regular floods. Due to their rapid onset, flash floods allow little time to warn the population. On average, 7.6% of the population living in the areas exposed to flash floods were affected, which corresponds to two times the rate of normal floods (3.7%). Regarding mortality, this difference is even greater, with 109 deaths per million people exposed to flash floods, compared to 6 deaths per million people exposed to normal floods.
Other studies show that the number of deaths as a proportion of the number of affected, tends to be higher for flash floods (4).

Despite recurrent events, mitigating the consequences of floods (especially flash floods) remains a challenge. We need better data collection on human impact (e.g. cause of death) to better understand the different dynamics between flash floods and riverine floods. Better knowledge will contribute to an improved response, adapted to the type of flood.

The 2018 Kerala Floods (Fig.B) were the worst in the region since 1924. Between August 7th and 20th, 504 people died and 23 million were directly affected by these flash floods. Economic losses accounted for 2.85 billion US$, the third costliest flood in India. This disaster also damaged or destroyed 110,000 houses, and deeply affected people’s livelihoods, with more than 60,000 ha of culture damaged and many animals killed. Finally, these floods damaged more than 130 bridges and 83,000 km of roads, causing the isolation of certain communities.

The Kerala flash floods had a heavy death toll. Lack of coordination in dam opening contributed to this disaster, as highlighted in our document review. The consequences of the flash floods were aggravated by deadly landslides (Fig. C). Experts believe deforestation and human construction played a role in these landslides, as they provoke runoff and do not Fig B: Flooded homes in Kuttanad Region-Kerala allow the soil to correctly absorb the excess water (5).