I am told that SriKrishna was an expert in recognising the locations where the Saraswathi river, which had begun to go underground, was trapped in artesian wells. He guided Arjuna to the spot that he would have to hit with his arrow, to release the water like a spring. The skillful and unquestioning Arjuna hit the spot deep with his arrow and water gushed out, reached Bhishma’s parched mouth and quenched his thirst.
I heard this from an economist who heard this from an archaeologist. Sri Krishna who was an expert in all sciences and technologies of the time (and of all times…) may have used technical clues to identify where Arjuna should shoot his arrow. In later texts such as the Brihat Samhita of Varahamihira and others., these have been documented. by a Professor of Archaeology who explains how groundwater locations may be identified from the surface – using a sastra called the Sivatattvaratnakara. I quote this Prof A.V. Narasimhamurthy below :
All these writers use trees and vegetation to locate water underground. Obviously there seems to have been some relationship between the trees and the underground water. Reference is made in this connection to trees like Banni (Shami), Nerale, Atti, Ala, tamarind, Bela, Ugani. Palm, Neem etc., to detect under-ground water. If anybody digs about five to six feet by the side of thornless Banni tree, water will gush out with good force. Similarly, water will be found at about 12 feet below the ground when dug to the east of Nerale tree with anthills. Likewise, if digging is done near the Lokki tree, one will get water at about 18 to 20 feet. There are some trees like mango, woodapple, bage etc., which show that water will be available if dug to about 25 feet.
Anthill is another index often mentioned by these writers. A combination of a particular tree near the anthill is a sure sign of underground water. Sivatattvaratnakara has a section on knowing the taste of the water even before starting excavations. Water will be sweet when there is red and black soil.
Underground water will not be found if the colour of the soil is red, ashy and yellow. Water will surely be found if the soil is mild red, mild brown or that of the colour of tender bamboo. Soil with copper ore, stones with coloured dots, ash coloured stones do not yield under – ground water.