The Hume Centre for Ecology and Wildlife Biology and the Advanced Centre for Atmospheric Radar Research of the Cochin University of Science and Technology (Cusat) have jointly set up a localised weather forecasting system for Wayanad district, a major landslip-prone area in the State.
“While the conventional forecasting systems focus mostly on district-wise rainfall, which has limitation in providing regional variation in forecasting, this new model predicts rainfall in 25 sq.km gridded platform, showing local variation in rainfall,” said S. Abhilash, Cusat meteorologist.
“Everyday forecasting resulted in 70% to 80% accuracy in spatial distribution as well as the intensity of rainfall. But we have to experiment for at least three years to understand the limitations in the modelling system and to further improve accuracy. The promising results of one year simulation is encouraging and appreciated by various stakeholders and there is also scope for customisation of the forecast products for various stakeholders,” said Mr. Abhilash.
The Western Ghats mountain ranges on the south-western side of the hill district attract clouds during the monsoon and precipitate heavy orographic rainfall. While the western side receives 4,000-mm to 5,000-mm rainfall annually, the eastern side, which is a rain shadow region, receives only 1,500-mm rainfall.
Though the district had shown a declining trend in the annual rainfall during the decade ending 2017, a sudden upsurge of extreme rainfall experienced in 2018 and 2019 resulted in a series of landslips and floods in Wayanad, due to climate change. Extreme rainfall ranging from 300 mm to 800 mm in 24 hours had been recorded during the past three years, and it resulted in major landslips, he said.
“One of the major objectives of this initiative is to provide day-to-day information about rainfall in different regions of Wayanad through a localised prediction system as well as widespread rainfall collection system in citizen science mode,” said Hume Centre director C.K. Vishnudas.
The district was divided into 107 grids of 25 sq.km for the purpose and a rain gauge and thermometer were installed in each of the grids except in forest areas. Currently, rainfall data was being collected from 93 locations of Wayanad and pooled into a centralised system for synthesis, said Mr. Vishnudas. The system helped provide localised warning to people living in mountain slopes about possible landslips when rainfall exceeded the threshold during the monsoon, he said.
The Hume Centre has already mapped all the landslip-prone areas of the district with a panchayat-wise landslip susceptibility map. So, the new tool of rainfall mapping would enhance the district’s capacity to combat disasters in the future, he said. The information generated from the system was being given to the District Disaster Management Authority for better decision making, he said.