High intensity rainfall which triggered back-to-back deadly landslides in Wayanad points to the need for an upgraded system for weather prediction. At 1 pm on July 29 when Mundakkai in Wayanad was receiving extremely heavy rainfall, the India Meteorological Department (IMD) gave an 'orange alert' (warning to be prepared) for Wayanad district. More than 12 hours later, the first landslide was reported in the area.
As per unofficial data, the rainfall recorded in the 48-hour period in nearby Puthumala (also in Wayanad district) was 572 mm, which comes under the extreme category. The IMD issued an updated red alert (warning to take action) by the morning of July 30, when Kerala woke up to the horrific news of the landslide that had wiped away human settlements in Mundakkai and Chooralmala. The death toll on July 31 crossed the 200 mark, while over 250 persons remain missing.
The 2018 floods in Kerala were cited as a wake-up call to address disaster management issues. However, the Wayanad landslide exposed the lacuna in the system and area-specific warnings and emergency alert systems are yet to get any priority in disaster management. Even the most vulnerable areas in the state lack proper rain gauges and weather systems.
Where is the second radar?
Following the 2018 floods, the IMD initiated steps to install a second Doppler Weather Radar as the existing one located in Kochi was inadequate to cover northern parts of the state, including Wayanad. Neetha K Gopal, director of IMD Thiruvananthapuram, said the second radar was planned for better coverage of the districts in north Kerala. She added that the department is yet to zero in on an ideal location for the installation of the radar. "Physical examinations of possible sites are going on," she said.
Dr MG Manoj, a scientist at the Advanced Centre for Atmospheric Radar Research, Cochin University of Science and Technology, said that accurate weather prediction demands radar every 100 km. “After 100-150 km, the visibility of clouds will be affected due to the curvature of the earth. It is like the Magellan's ship where we first see only the mast. We might be accessing the intensity of rainfall from the top portion of the cloud. However, like an iceberg, it can be dense below that level. That could affect the accuracy of the prediction of north Kerala districts,” he said.
Area-specific alerts
There was a call for better and accurate weather prediction systems that could provide area-specific alerts after the 2018 floods and 2019 landslides. IMD's bulletin gives only district-wise alerts in colour-coded categories and only at specific intervals of 10 am, 1 pm and 4 pm. Even after the disaster, authorities are forced to depend on unofficial data to analyse the intensity of rainfall. Post-2018, IMD took a proactive step to install an additional 100 automatic weather stations (AWS) in the state, which helped increase the total tally to 130. However, sources said that some are not fully functional yet. “This week, the AWS at Padinjarathara showed a rainfall of 333 mm in 24 hours, which the IMD termed inaccurate,” a Kerala government official said. In Wayanad, the AWSs are in Ambalavayal, Kabanigiri, Kalpeta, Karapuzha, Kuppadi, Padamala and Padinjarathara.
The total requirement of AWS, according to a report from Kerala State Disaster Management Authority, is 256. Manoj said that Kerala has only half of its requirement of rain gauge stations. He said that ecologically fragile areas should be given priority in the installation of AWS.
As per reports, Hume Centre For Ecology And Wildlife Biology, a Wayanad-based weather research institute, had alerted the district administration and Kerala State Disaster Management Authority on July 29 regarding the extreme rainfall and possibility of a landslide in the area. As per the information available on the social media page of Hume Centre, it has a community-driven initiative to analyse the weather in Wayanad. It has installed a series of rain gauges in houses, farmlands and schools.
Neither the state government nor IMD has taken any steps to integrate such community initiatives for its weather monitoring. Gopal said that the IMD could only accept rain gauge stations that would meet the standard conditions set by the World Meteorological Organisation. Gopal, however, added that they had begun discussions with the state Chief Secretary to integrate AWS under various state government departments with IMD.
Automated Weather Stations collect real time data, including measures of rainfall, wind, humidity, soil moisture etc and transmit it every 15-minute interval, while Doppler radars can be used to track clouds, weather systems and measure rainfall. In Kerala, IMD has a Dual Polar S-Band Doppler Weather Radar which is used to track cyclones, wind flows and rain activities in Kochi and areas within a horizontal range of 500 km.
Regarding the orange alert issued on July 29, Gopal said that the alert warns of very heavy rainfall of up to 200 mm in 24 hours in an area. A red alert is issued if rainfall of over 204 mm is expected in a 24-hour period. But Puthumala recorded 372 mm of rainfall in 24 hours, nearly twice the amount of rainfall expected in case of a red alert.
In a press meet held on Wednesday evening, Kerala Chief Minister Pinarayi Vijayan said that the IMD sounded a red alert only by 6 am on July 30. "Only an orange alert was predicted for the disaster-hit area. IMD predicted a rainfall between 115 mm and 204 mm. However, the area received 200 mm of rainfall in the first 24 hours and 372 mm in the next 24 hours. In 48 hours, there was 572 mm of rainfall, which was much higher than predicted. No red alert was issued anytime before the disaster," he said.
Gopal said that extreme weather events were not specific to Kerala, but a global phenomenon. She said that the Union government has begun discussions for steps to provide area-specific weather prediction and to increase the duration of bulletins.