Cave-in at Polavaram road: Officials blame mudcrack, but experts differ

VIJAYAWADA: What caused the gravel road abutting the Godavari near the Polavaram dam site to cave in, creating panic in as many as 13 villages on Saturday? Were the large cracks on the road, extending up to a km long, due to simple mudcracks or ground subsidence with wider environmental reasons behind the rare phenomenon?
Officials may have washed their hands of the Polavaram incident by citing mudcracks as the reason for the caving-in of the road leading up to the ambitious project. A deeper analysis of the cracks on the metal road, however, reveals that it is a clear-cut case of land or ground subsidence and not mudcrack.

Environment activists attribute it to several serious factors ranging from environmental to man-made. They demand that the government hold a thorough scientific investigation of the region to pinpoint the exact reason and find remedial measures instead of dismissing it as a simple case of mudcrack.

Soon after a km-long portion of the Polavaram road caved in with deep fissures on Saturday, Polavaram chief engineer V Ramesh Babu told media that the road developed cracks due to drying up of the moisture content in mud. This in other words means the road caved-in due to mudcrack. Mudcrack is a common phenomenon in soils made up of mud. As the moisture content evaporates, the upper portion of the soil contracts leading to formation of cracks, scientifically known as mudcrack.

But the type of deep cracks or fissures on the road reveal that it was not a mudcrack but ground or land subsidence. Mudcrack is common in agricultural fields but the depth of the cracks are shallow. In the Polavaram case, the fissures are deep, up to five metres.

"Only a thorough scientific investigation would reveal the exact cause behind Saturday's phenomenon. The area is ecologically fragile. It is close to a large river. A huge dam is under construction a few km away from the area where the road caved in," said environmental activist V Satyanarayana.

"Non-earthquake fissures coupled with ground subsidence should be studied in detail. Such things appear due to reasons like overdrawl of groundwater, heavy load on the ground, palaeochannels, and extinct river courses," Satyanarayana said.