27,000 in flood relief camps: How one climate disaster in Kerala is worsening the next

The 2018 floods, which had deposited huge amounts of sediment into the rivers, aggravated the situation, reducing their capacity to carry water — especially during flash floods.

Landslides in hilly and forest areas also deposited huge volumes of soil and sand in river beds. Sediment accumulation has also resulted in formation of deltas, which obstruct the flow of floodwater.

Severe soil erosion causes a riverbank collapse along the swollen Chaliyar River, threatening houses at Mundengara in Malappuram district, Kerala, on Tuesday, Aug. 4, 2026. PTI

Sedimented reservoirs

The extremely heavy rains have increased the water level in all dams, run by both the state electricity board and the irrigation department. A CAG report in 2021 had found a significant fall in storage capacity of dams due to sedimentation.

The report said Kerala State Electricity Board Ltd (KSEB) had not conducted any sedimentation studies in its reservoirs after 2011. The report said the Kallarkutty dam had lost 47% of gross storage in 45 years while the figure for Anayirankal dam was 30.92% in 33 years.

The KSEB has not conducted any more studies to assess the change in silt deposit and reduction in the capacity of the dams. It had initiated a tender process for desilting a minor dam at Vellathooval in Idukki and while the irrigation department did so for Chulliyar dam in Palakkad.

Disappearance of wetlands and paddy fields

Rapid urbanisation, coupled with change in land use patterns, have shrunken the state’s paddy fields, marshlands and wetlands, which would have absorbed a huge volume of rainfall. According to data from the state statistics department, Kerala had had 7.93 lakh hectares of land as paddy in 1979-80. This fell to 2.05 lakh hectares in 2020-21 and to 1.80 lakh hectares in 2023-24.

The marshland area, which had been 974 hectares in 2005-06, fell to 974 hectares in 2015-16, before going down to a mere 11 hectares in 2019-20.

Wetlands, which had covered 5,950 hectares in 2005-06, fell to 2,937 hectares in 2023-24.

Gates of the Kallarkutty Dam are opened amid heavy rainfall, in Idukki on Saturday. ANI

This disappearance of wetlands and paddy fields have reduced the state’s capacity to cushion the impact of flash floods and heavy rainfalls.

Kerala’s altered natural hydrology

Kerala’s dense network of concrete roads, tarred lanes and paved surfaces across both rural and urban areas has significantly altered the state’s natural hydrology. During heavy rains, these impervious surfaces channel stormwater rapidly into nearby rivers and streams, causing water levels to rise within hours.

This rapid runoff has become a defining feature of the state’s landscape, where tarred roads and concrete pavements extending from the hills and other high-lying areas effectively function as channels for stormwater. As a result, many roads in low-lying areas become inundated within a short time as large volumes of runoff rush downstream from these paved surfaces.

What the government plans

The state government is planning to desilt rivers and reservoirs to ensure that they have enough room to hold water. Chief Minister Satheesan on Wednesday said: “There is no room for water to flow. A heavy spell of rain can leave our rivers swollen or overflowing. To lower the threat of floods, the sedimentation in rivers and dams will be removed urgently. An asset register will be prepared for rivers, streams and lakes and land auditing will be conducted to prevent encroachment of rivers,” he said after the cabinet meeting.

Mining of sand from rivers and reservoirs can also act as a source of income for the government.  Till a decade back, sand mining in rivers had been widespread, but was banned following indiscriminate mining, which raised environmental concerns. Besides, after the manufactured sand (made from pulversing rock) gained dominance in the construction sector, the demand for river sand had gone down.