Kerala is described as 'God’s own country' in India, with magnificent natural landscapes and fertile valleys. However, unprecedented summer monsoon rainfall throughout June, July and August has left a wake of devastating floods across the state.
Illustration of flooded location around the Aluva, Thrissur and Chalakudi districts of Kerala, India. JBA India River Flood Map (50-year return period) is provided for context.
The livelihoods of many in India are highly dependent on agriculture. Agricultural yield in turn is highly dependent on the monsoon season. India receives 80% of its annual rainfall in just three months. This year, Kerala state in the southern peninsula has received 37% more rainfall than average in just two months (India Meteorological Department (IMD)).
The most recent flooding has been due to a low-pressure zone above the southern peninsula, causing prolonged rainfall in Kerala most of last week (week commencing 13 August 2018). The flooding has been widely described as the worst in the last century, with notable comparisons to the catastrophic floods of 1924.
As floods and landslides have engulfed households and farmlands, more than 375 have died (Reuters). A large majority of the people died due to landslides caused by the floods. Idukki and Wayand were the states most affected by landslides, with an estimated 1.2 million people now in temporary shelters (Reuters).
Further issues have continued for many as shelters face shortages of water and medical supplies, given that roads are impassable in certain areas (BBC UK). In some places, young children and the elderly have been airlifted to safety. Total economic losses are estimated at USD $2.8 billion thus far and are likely to increase as recovery efforts continue (Reuters/ Singapore Straits Times).
Past rainfall records
In less than a month (1– 20 August 2018), Kerala received a total of 771mm of rainfall which was found to be 255% higher than normal (IMD, Times of India). The graph to the right illustrates past rainfall amounts in Kerala state for years between 1901 to 2015 (Data source: India Meteorological Department). 
Before August has come to an end, the rainfall received in 2018 has already exceeded that of 2014. The most significant event was recorded in 1931 at 1.2m and was comparable to past large events in Kerala. Officials have described this 1931 event as a 1-in-100-year event and often compared the extent of destruction to that of the 1923 flood.
DAMAGE TO CROPS
Due to the recent continuous rainfall, large agricultural farms have been flooded, with estimated crop losses between USD $71 million and USD $101 million (The Times of India). Coffee, rubber, tea and black pepper are amongst some of the crops worst affected. In rural Kerala, many farmers may not be able to recover quickly enough to harvest any yield this season. Farmers in rural areas may also lack access to adequate insurance cover to aid their recovery process.
LESSONS LEARNT
The Kerala floods have served as an important reminder of the impact of water management programmes and flood mitigation measures. It seems that water management may be partly responsible for exacerbating the situation. With a total of 44 rivers flowing through the state of Kerala and many dams, officials in the field have agreed that the floods were likely worsened due to management of the dams. The dams held back water for a long period until it reached critical levels and had no choice but to release most of the dams at the same time (BBC UK). At least 30 dams, including major ones like Idukki and Idamalayar, were forced to release its water when the torrential rainfall continued.
In addition, local state authorities mentioned that the official Central Water Commission (CWC) did not provide early flood warning in advance as there were no flood forecasting sites in Kerala. Rapid development and deforestation have also been cited as increasing the likelihood of such flash flood events in Kerala (Hindustan Times).
The South Asia region is likely to experience an increase in runoff between 2046-2075 as compared to the average baseline measured from 1976-2005 (Floodlist). Hence, it is critical to have relevant mitigation measures in countries and states that are at high risk. In addition to India, low lying areas such as Bangladesh and Myanmar are facing similar threats. By understanding the areas at risk, we are able to adapt suitable measures in preparation for future events.
JBA Risk Management has nationwide return period flood maps for India at 30m resolution. Please contact us for further information.
References
BBC, 2018, 'Kerala Floods: Troops Rush In To Help Rescue Efforts', viewed 20 August 2018
BBC, 2018, 'Why the Kerala Floods Proved So Deadly', viewed 20 August 2018
Bhaskar, U., 2018, 'Relentless Rain Brings Kerala to a Standstill, Death Toll Rises Above 100', LiveMint, viewed 21 August 2018
Chauhan, C., 2018, 'Kerala Floods: Poor Dam Management Behind Disasters, Experts Say', Hindustan Times, viewed 21 August 2018
Floodlist, 2018, 'Global Warming to Increase Water in South Asian Rivers', viewed 20 August 2018
Ganapathy, N., 2018, 'Long Road To Recovery as Kerala Floods Recede', Singapore Strait Times, viewed 21 August 2018
Madaan, N., 2018, 'In Just 20 Days, Kerala Gets Highest August Rains in 87 Years', The Times of India, viewed 20 August 2018
Menon, M. and Varadhan, S., 2018, 'Death Toll Nears 400 in India's Flood-Hit Kerala, Dozens Missing', Reuters, viewed 21 August 2018
The Times of India, 2018, 'Damage to Crop, Property in Kerala Floods Pegged at Rs 8,000 Crore So Far', viewed 20 August 2018