Two cyclonic circulations and merger of wind systems behind Eturunagaram tree havoc

The high speed winds exerted shear stress on the trees resulting in their being uprooted in the Eturunagaram Wildlife Sanctuary, explained experts.
| Photo Credit: SPECIAL ARRANGEMENTS

Two cyclonic circulations, and merger of four wind systems could have resulted in the disaster experienced by the Eturunagaram Wildlife Sanctuary on August 31, when 50,000 to one lakh trees were uprooted en masse in a linear pattern at Tadwai in the forest.

Climate experts attending a workshop hosted by the Forest department on the mysterious phenomenon shared that there were two cyclonic circulations over mainland India, one from Rann of Kutch in Gujarat, and another from Odisha and Andhra Pradesh.

A squall line was formed connecting these two cyclones, resulting in torrential rainfall over Mulugu, Mahbubabad, Khammam and Suryapet districts, all of which experienced flooding.

Experts from the National Remote Sensing Centre shared observation of four airmass activities, which merged over a period of time over the region in Tadwai, and formed tall clouds. When they hit the ground, local high speed winds were created, exerting shear stress on the trees, resulting in their being uprooted.

The windspeed was 130-140 kilometres per hour, which is usually observed in cyclone-hit areas, a forest official who attended the workshop said. A tornado was categorically ruled out, as it would have scattered the trees in all directions unlike here, where the trees fell in a linear pattern.

Scientist from National Atmospheric Research Laboratory (NARL) Amit P. Kesarkar and M. V. Ramana from National Remote Sensing Centre explained the climatic developments on the day, while Tanvi Arora from the National Geophysical Research Institute demystified the behaviour of trees.

Ms. Arora, speaking to The Hinduexplained that the soil thickness was very shallow in the region, typical of alluvial sandy loam. The trees might not have grown properly, as evidenced by the root penetration which was horizontal rather than vertical, she said.

Further, three days of continuous rain totally saturated the soil, which could have made the roots rotten, she said.

Principal Chief Conservator of Forests and Head of the Forest Force R. M. Dobriyal said about 332 hectares of forest has been affected by the calamity. He instructed the forest staff to protect the area from biotic interferences and fire. Special attention should be paid to wildlife protection, and prevention of weed growth.

District Forest Officer, Mulugu, Rahul K. Jadhav made a presentation in the workshop about the natural catastrophe, which, he said was unheard of earlier.