Flash floods in Kerala: A junked breakwater plan may have been Achilles’ heel

Flooding revealed lack of disaster preparedness; more rain expected this week

By K A Shaji
Published: Wednesday 18 October 2023
A flood mitigation project titled Operation Anantha included a breakwater at Veli so that excess water from Akkulam lake (in pic) would drain out to the sea through the year. Photo: iStock__

Kerala is expected to experience moderate to heavy rain along with thunder, lightning and flooding over the course of the upcoming week, according to the India Meteorological Department (IMD). The southwest monsoon, which usually ends by the end of September, is still in effect, making the state appear extremely unstable.

Flash floods drenched Kerala’s capital, Thiruvananthapuram, for approximately 48 hours beginning the night of October 14, 2023. Most low-lying areas of the city are still under water. Significant rains were recorded in the districts of Ernakulam, Kollam and Alappuzha on October 18 as well, creating waterlogging and stagnation in several regions.

Weather patterns have been irregular since June, when the monsoon season began, causing irreversible damage to the state’s agricultural calendar and severely affecting other livelihood sectors such as fisheries and small-scale food processing.

Kerala has seen heavy rains in the previous 15 days — since October 1, Thiruvananthapuram has received 158 per cent more rain, while the state has received 19 per cent excess overall. 

Despite the continuous heavy rains, the Idukki reservoir, which produces the majority of Kerala’s hydropower, was just 36 per cent full as of October 17, down from 81 per cent on the same day last year. 

There was no rain in June or July and only minor precipitation was seen in August, raising concerns about an impending drought. Little rain has fallen in the catchment areas of hydroelectric power projects in Idukki and Pathanamthitta, raising fears of load shedding and power outages.

The irregular rainfall has caused concern because the North East Monsoon has yet to arrive. While the rainfall gap is closing, analysts are unsure whether there will be compensatory extra rainfall to help recover from the drought threat or if the North East monsoon will be poor by the end of October, which could exacerbate the problem.

The recent torrential rains in Kerala were caused by cyclonic circulations over the Arabian Sea and Lakshadweep, according to the IMD. Meanwhile, various groups, including ministers, have accused the IMD of failing to issue a warning.

Now, thunderstorms with light to moderate rainfall and strong winds are expected across the state, particularly in northern Kasaragod for the coming week. 

The torrential rains in Kerala since October 14 have exposed flaws in the state’s disaster preparedness in urban areas, as many of the areas affected by the latest urban flooding in Thiruvananthapuram were near newly built-up areas or were not listed on the Kerala State Disaster Management Authority’s flood hazard map.

Thiruvananthapuram city recorded an unprecedented 211.4 millimetres of rainfall in the 24 hours ending at 8.30 am on October 15. However, the rainfall data from the days before — 21.4 mm on October 14, 4.6 mm on October 13 and 12.55 mm on October 12 — indicate that the soil was not saturated with moisture. 

Why the flooding occurred

In the standard scenario, the Amayizhanchan Canal near Kannamoola connects to Akkulam Lake and drains rainwater into the Arabian Sea via Veli Pozhi, an estuary. But the final component of the project titled Operation Anantha is missing — which may have led to flooding in the city. 

The flood mitigation project included a breakwater at Veli so that excess water from Akkulam lake would drain out to the sea through the year. However, its construction was halted following opposition from the Veli locals.

The opposing group of local residents claimed that the breakwater would cause the city’s chemical effluents and plastic waste to drain into the marine ecosystem. However, their main concern was coastal erosion on one side of the structure, which could have taken away an entire portion of the nearby land. 

Following the opposition, the proposal was abandoned, despite a Rs 10 crore tender being submitted to the Harbour Engineering department. 

In recent decades, the city’s built-up area has also increased significantly. When the initial urban drainage master plan was developed in 1932, its population was only 100,000. However, the 2011 census showed it had grown to around a million and is likely even higher at present. Many areas that have seen rapid flooding, like the Kazhakuttam substation and a significant chunk of Technopark’s phase-III campus, are also built on formerly swampy terrain. 

According to a senior KSDMA official, rapid urban flooding occurs when there is insufficient infrastructure to allow water to quickly drain into the sea after rain.

“To avoid such flooding, we must digitally map land-use changes in urban landscapes across the state at least once every three years. The most recent incident emphasises the importance of preserving remaining wetland or marshy lands in cities,” he said on condition of anonymity.

Meanwhile, the Centre for Water Resources Development and Management (CWRDM) in Kozhikode has encouraged the government to build early warning systems, infrastructure that can withstand water overflow and suitable land-use planning to mitigate the effects of seasonal floods in Kerala.

The CWRDM published a document on October 16, 2023 titled Rivers and Rain 2022: Assessing Kerala’s Water Sustainability, a Status Report. The state’s intricate hydrology and high variability of rainfall makes managing the state’s water resources a difficult undertaking. The report suggested a multifaceted approach for water management that includes conservation, distribution and sustainability.

Check dams have been suggested to prioritise watershed-based management, afforestation and soil conservation. To combat drought, CWRDM recommended water-efficient farming practises, including the use of drought-resistant crops and the implementation of water-saving measures such as micro-irrigation.

Following the flooding on October 14, 550 people were moved to 17 relief centres in Thiruvananthapuram. Almost all of the district’s rivers and canals continue to overflow. The administration has advised particular vigilance against the spread of infectious diseases in areas hit by the rains due to floods and waterlogging in parts of the state.

According to state Health Minister Veena George, as water recedes from flooded and waterlogged areas, there is a risk of the spread of infectious diseases such as leptospirosis, which is caused by contact with water or soil contaminated with animal urine, such as rats.

District surveillance be improved and awareness campaigns be expanded, in addition to ensuring drug availability, the administration further suggested.

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