Rescuers carry a victim of a landslide caused by torrential monsoon rains in Meppadi in Wayanad district, Kerala. Image Credit: Reuters

Thiruvananthapuram: As relief operations progress in multiple districts in Kerala after the loss of nearly 100 lives and a quarter million flood victims landing in relief camps, a worrying new threat has emerged in the state in the form of soil piping.

Also known as soil contact erosion, soil piping happens when water seeps along the interface between coarse and fine soils, eroding the particles from the finer layer into the coarser layer. Excessive rain, strong current of underground water sources and the soil characteristics can all contribute to soil piping.

It starts as an erosion of underground water, creating an underground tunnel called the soil pipe. Over a period of time, the constant flow of water along the pipe erodes the surface earth resulting in a collapse of the earth above.

After the 2018 flood, scientists from the National Centre for Earth Science Studies (NCESS) had conducted an investigation and found that land subsidence, lateral spread and soil piping were immediate threats to life and property, particularly in the highlands.

Soil piping was detected in Paikadan Mala in Kozhikode district, where 10 families have been temporarily rehabilitated in the wake of heavy rains in the district and concerns about soil piping in the area.