Kolkata: Amid reports that its warning system "failed" in landslide-hit Wayanad in Kerala, the Geological Survey of India (GSI) on Friday said its regional forecast bulletins for the district were experimental and issued once a day for ground testing.
This process was a "part of building a prediction model", which will take 4-5 years to be ready for public use, a GSI official said.
"GSI has started issuing regional landslide forecast bulletins on an experimental mode once a day for Wayanad district, Kerala. These are issued only to the State Disaster Management Authority (SDMA) and District Disaster Management Authority (DDMA) for ground testing since the onset of the 2024 monsoon. It is restricted only to SDMA and DDMA for receiving feedback," a GSI spokesperson told PTI.
These forecasts are based on rainfall predictions provided by the National Centre for Medium-Range Weather Forecasting (NCMRWF) and the India Meteorological Department (IMD) to prepare landslide thresholds, he said.
Massive landslides triggered by torrential rain struck the Wayanad district early Tuesday morning, leaving behind a trail of destruction. The death toll climbed to 195. With nearly 200 people missing, the toll is expected to rise.
"The experimental landslide forecast provided for Wayanad was only for "validation and ground testing purposes and is not for public use", he said.
Between July 26 and July 30, GSI issued bulletins on all days except July 28, when the system for the experimental forecast was down, the official said.
The GSI landslide forecasts were "low" on all days for Wayanad district except for a "moderate" prediction on July 26 for Vythiri Taluk and on July 30 for Vythiri and Mananthavady Taluk, the surveyor said.
The GSI emphasised that extensive ground testing over four to five monsoon years is required before the model can be made available for public use.
"It may be noted that the probable source areas of the debris flow fall within the high and moderate susceptibility zones delineated by GSI," the official stated.
Meanwhile, Kolkata-headquartered GSI has recently operationalised a landslide forecasting system only in Darjeeling and Kalimpong districts of West Bengal and the Nilgiris of Tamil Nadu from July 19 for public use, only after ground testing in experimental mode since 2020.
The ground testing activities by GSI for at least 13 more districts were in progress and the surveyor expects to cover most of the landslide-prone districts by 2030.