July 2020 study by Indian Institute of Science raises questions about dam management and points to need for improved, region-specific rainfall forecasts
The findings of an Indian Institute of Science (IISc) study on the devastating 2018 floods in Kerala have been spotlighted by the opposition UDF ahead of the Assembly elections to back up its claim that the disaster was avoidable and that the LDF government mishandled the situation.
The July 2020 study, carried out by the IISc’s Interdisciplinary Centre for Water Research (ICWaR), raises pertinent questions about dam management and points to the need for improved, region-specific rainfall forecasts and judicious land use for flood mitigation. The office of the Accountant General (Audit 1) here had engaged the services of the IISc for the study.
On March 30, the Leader of Opposition Ramesh Chennithala said that the IISc finding was a ”charge sheet” against the LDF government. Former Chief Minister Oommen Chandy told a press conference here on Thursday that the UDF would take necessary follow-up action if it came to power as scientific studies have proven that the disaster was man-made.
Citing reservoir authorities, the study notes that the rule curve was not followed for reservoir operations in Idukki and Edamalayar during August 14 to 18, the peak flood period. The flood cushion between full reservoir level (FRL) and maximum water level (MWL) was not utilised in Idukki during the period. If the flood cushion of 110.42 million cubic metre (MCM) had been used, initial spills could have been reduced. At the Idamalayar dam, the storage volume between full reservoir level (FRL) and maximum water level (MWL) was partially utilised, but the flood cushion was not utilised to its full capacity, it says.
Absence of forecasts
Absence of accurate rainfall and flow forecasts affected reservoir operation during the flood period, the study notes. Although the Indian Meteorological Department (IMD) furnished rainfall forecasts during the period, they were ”not region-specific within the district and were also not accurate,” it noted.
Analysing land use land cover (LULC) changes between 1985 and 2015 for assessing their impact on the floods, the study found a significant increase in the built-up area in Idukki and Ernakulam districts. During this period, the built-up area in Idukki district increased by nearly 1,257% — from 11.39 sq. km in 1985 to 154.57 sq. km in 2015 — and in Ernakulam district, by nearly 212% — from 140.65 sq. km to 439.14 sq. km.
The LULC analysis for the flood-hit regions in Ernakulam district situated in the Periyar basin shows a notable increase in built-up area by nearly 277% — from 48.44 sq. km in 1985 to 182.59 sq. km in 2015, notes the report. Between 1985 and 2015, water bodies in the flood-hit regions had decreased by 31.7% — from 93 sq. km to 63.5 sq. km, the study found.
Water bodies decreased by 5.8% — from 120.26 sq. km in 1985 to 113.24 sq. km — in Idukki district and by 14% — from 219.51 sq. km in 1985 to 188.81 sq. km — in Ernakulam district.
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