Kerala should explore the possibility to create a storage dam on Achenkovil river for flood moderation and other multi-purpose use, according to N.N. Rai, Director, Hydrology (South) of the Central Water Commission (CWC).
"There is no storage dam on Achenkovil River. During the heavy rainfall, the runoff generated from the catchment of this river causes heavy flooding in the downstream area and some relief from flooding in these areas can be realized by storing the flood water in a storage dam," he told The Hindu.
Mr. Rai said that some additional water storage possibility should also be explored in Pampa sub-basin for flood moderation.
On the aspect of reservoir operation and management amidst the increasing extreme climate events in the State, the CWC's Director, Hydrology (South), pointed out that the reservoir should be operated as per rule curve. "If the reservoir level is between conservation rule level and upper rule level, it shall have some capacity to store the flood water and helping mitigation of flood in downstream areas," he said.
Mr. Rai said that the State government is operating the reservoirs as per the rule curve and it is providing the flood relief to the downstream area.
When asked about the effective steps to be taken for effective flood risk management in the State, Mr. Rai said that some flood zoning corresponding to at least 5 years to 25-year return period floods may be considered by the Kerala government.
"Further, for the rivers in Kerala, the inundation mapping may be carried out for 2, 5, 10, 25, 50 and 100-year return period floods, and based on the IMD rainfall forecast, people residing in flood plains should be alerted in order to save the loss of lives. Necessary regulations to avoid the flood plain encroachments are also essential," he said.
A report prepared by the Hydrology (South) Directorate of the CWC after the massive floods in 2018 had found that the absence of appreciable storage reservoirs in the upstream of Pampa, Manimala, Meenachil and Achankovil rivers along with the shrinkage of the carrying capacity of Vembanad Lake and reduction in the capacity of Thottappally spillway worsened the flooding in the Kuttanad region.
