The Central Water Commission (CWC) has developed a library of possible inundation scenarios in the Periyar river to help the Kerala government manage large-scale floods in the future.
The scenarios have been generated for readily picking up the most likely one corresponding to the water level of the flood predicted for any point on the river, Sharad Chandra, CWC’s Director of Flood Forecast Monitoring, told The Hindu in an email interview.
Mr. Chandra said the model had been validated by successfully simulating the river flow data as observed at Neeleswaram on the Periyar for past 35 years, including the flood events of 2018.
Feasibility
“Further, the feasibility of providing conventional gauge-to-gauge correlation-based Statistical Level Forecast for Kumbidi on the Bharathapuzha, Neeleswaram on the Periyar, and Malakkara on the Pampa has also been studied,” he said.
“However, there is scope of refinement to availability of historical data of reservoir outflow/inflow, river/reservoir bathymetry (measurement of depth of water in oceans, seas, or lakes) at finer resolution, high-resolution terrain topography, and finer spatial and temporal resolution of rainfall data,” he added.
Close watch
Mr. Chandra said the CWC was keeping a close watch on the present heavy rainfall (between August 6 and 10) warnings for any sudden increase in water level or inflow into dams. “Forecast, if required, will be issued if the criteria fixed by the project authorities are exceeded,” he said.
The CWC has operationalised Level Forecast Stations at Malakkara on the Pampa in Pathanamthitta district, Neeleswaram on the Periyar in Ernakulam district and Kumbidi on Bharathapuzha in Palakkad district.
This was done as per the recommendations for starting three such stations using conventional flood forecasting model with a warning time of 12-24 hours, and a mathematical model for three-day advisory for inflow forecasting to the Idukki and Idamalayar dams.
Forecast stations
Mr. Chandra said two inflow forecast stations in Idukki and Idamalayar in Ernakulam district have also been operationalised.
“Inflow forecasts were issued during the rain spell in the second week of July 2019 to the dam authorities and to the State government.
The forecasts are disseminated as and when they are formulated as per standard operating procedure and immediately sent to the District Collectors and project authorities through email.
“It is also uploaded on the CWC Flood Forecasting website http://india-water.gov.in/ffs for wide circulation,” he said.
