July 2024 marks 100 years of the greatest flood in the history of Kerala that tested the endurance and the mettle of a generation. The State witnessed two more catastrophic floods—in 1961 and 2018—after that flood in 1924, considered one of the deadliest in the history of the State given the magnitude and scale of destruction.
The flood, also known as the Great Flood of 99 as it happened in the year 1099 of the Malayalam calendar, washed away villages and hills and submerged around half of the then Princely States spread across Travancore, Cochin, and Malabar. As the State silently observes its centennial anniversary, a cursory glance at the meteorological features of the three devastating floods elicits some interesting facets about the changing climate scenario in Kerala.
Comparative analysis
A soon-to-be-published book Gateway of Monsoon, written by P.S. Biju, a senior scientist at the India Meteorological Department (IMD), contains a comparative analysis of the meteorological features of the floods. As per the IMD records, Kerala recorded the highest rainfall in its recorded history in 1924 — 3451.3 mm, an excess rain of 71% — followed by 3229.3 mm in 1961, an excess of 60%. When these floods are compared, a similarity can be seen in the skewed distribution of the rainfall over the four-month southwest monsoon season. On both the occasions, Kerala received a whopping quantum of rainfall in June and July. These two months alone netted over 2,000 mm of rain, quite higher than the four-month seasonal cumulative rainfall. Further, 1923 had seen the third-highest southwest monsoon rainfall in the 123-year-old recorded history of the State.
The soil was highly saturated the previous year due to above normal monsoon and pre-monsoon showers. This, along with excess precipitation in the opening two months of the monsoon season in 1924, led to a rapid flood as the saturated soil could not absorb the excess runoff. In the case of the 1961 flood, the monsoon season of the previous year (1960) was normal, but the torrential downpours in June and July led to flooding, although the scale and magnitude of the destruction were relatively less.
When it comes to 2018, the excess precipitation in August led to the flood, though the monsoon in 2017 was normal and was below normal in 2016. Though another flood followed in the 2019 monsoon season, the magnitude was relatively less compared to 2018. Here again the excess precipitation in August caused the flood.
Saturated soil
Mr. Biju told The Hindu that the floods in the millennium provided some foresight for future planning. Even a normal monsoon in June and July followed by excess precipitation in August would prove to be calamitous for Kerala as the saturated soil could not absorb excess precipitation. “We cannot say that the excess rainfall in August will be a trend, as August 2023 was the driest-ever month in the recorded history of Kerala. But an excess rain in August has the potential to create flashfloods in Kerala,” said Mr. Biju.
Published - July 22, 2024 09:05 pm IST
