Warning system must be in place to minimise loss of lives: Expert

Guwahati: Experts have insisted on prediction of landslides in vulnerable hilly areas of the northeast to minimise loss of human lives by adapting state-of-the-art early warning systems after the Manipur disaster.
Rainfall-induced landslides are shallow in depth, in general, and rainwater infiltration into the soil decreases the sheer strength of the soil, they said. As the Manipur tragedy has been an eye-opener, experts said extra precautionary measures are a must to prevent such disasters in future.
“Natural slopes contain negative pore pressures and provide additional shear strength of the soil to support steep slopes. The negative pore pressure/sheer strength, however, decreases due to rainwater infiltration into the slope. During the critical rainfall event, the factor of safety of slopes automatically decreases to less than 1, which causes landslides,” said Dr Tadikonda Venkata Bharat, professor, department of civil engineering and associated faculty at Centre for Disaster Management and Research, IIT-Guwahati.
“Toe of the slopes should not be disturbed during construction and the rainwater and drainage should be properly diverted during and after construction works,” he added.
Similarly, Prof. Bharat said the slopes, during the construction, can be protected against rainfall infiltration by covering with Tarpaulin sheets, which is found to be a good, temporary measure.
“Generally, slopes in the hilly terrain are protected by retaining walls to support the slopes from collapsing during construction. However, use of improper backfilling material causes buildup of pore pressure that can destabilise the slopes or lead to collapse of the walls,” he added.
Bharat said understanding the geotechical characteristics and adapting proper engineering measures before construction in hilly areas would help in preventing failure of human-intervened slopes.
“Prediction of landslides helps in minimising loss of lives and damage to property. Adapting state-of-the-art early warning systems at vulnerable hilly areas provide ample time to evacuate people before the disaster,” he said.