By Ritambhara
Varahamihira, the 6th-century astronomer of Ujjain, wrote one of the earliest field manuals for finding groundwater. It sits inside his Brihat Samhita, an encyclopaedia of roughly 100 chapters that covers planets, weather, crops, architecture and gems.
He described himself as a native of Avanti, the region around Ujjain, and lived in the village of Kapitthaka. His astronomical work, the Pancha Siddhantika, uses an epoch of 505 CE. The mathematician Brahmagupta cited him in 628 CE.
A chapter on water under the ground
The chapter on groundwater is called Dakargala, numbered 54 in the National Institute of Hydrology’s 1990 study Hydrology in Ancient India. It covers how the water table varies from place to place, hot and cold springs, and the digging and lining of wells.
Its method is observation. Varahamihira lists trees, shrubs, soils, rocks and animal signs that point to water below. A tree of a given species with a termite mound beside it indicates water at a stated distance and depth. He also notes the chance of water where ant hills stand near tender bamboo.
E A V Prasad, a geologist at Sri Venkateswara University in Tirupati, tested these claims against modern science. In a 1980 paper in the Journal of the Indian Institute of Science, he concluded that Varahamihira used the form and behaviour of plants as hydrological indicators. The text’s indicators cover depths from about 3.4 metres to 171 metres. Prasad linked them to higher humidity and lower water loss from leaves in the soil pockets above aquifers in dry regions.
Termite mounds tested in Tamil Nadu
Termite mounds have drawn the most modern attention. Geoscientist T S Badrinarayanan and Prasad used mounds to site bore wells in Palladam, Pollachi and Udumalpet taluks of Coimbatore district. Most of the 24 wells drilled gave useful yields. They cautioned that a mound alone is insufficient and that a systematic survey is still needed.
A 2018 review by J B Ahmed and B Pradhan in the Pertanika Journal of Science and Technology reached a similar view. Mound soil passes water more easily than the ground around it, and mounds often line up along water-bearing dykes and seepage lines. The authors called the method promising and flagged open questions on its reliability.
The weather pages
The Brihat Samhita also carries a run of chapters on rain. They cover the “pregnancy of clouds”, signs of immediate rain and the circle of winds. Each one rests on watching the sky and the season over long periods and recording what followed.
The lesson for an overdrawn country
India now extracts more groundwater each year than China and the United States combined, according to the World Bank and WaterAid’s 2019 State of the World’s Water report. Modern drilling has made water easy to reach and hard to account for.
Varahamihira’s method worked the other way. It asked the digger to read the land before breaking it and to treat each tree and mound as evidence. India’s groundwater planners now have satellites and sensors he lacked. His rule still applies to them: survey the surface first, then drill.
