ESTIMATION OF AQUIFER TRANSMISSIVITY FROM RESISTIVITY DATA AROUND ROORKEE, INDIA

Abstract

Ground water is a precious and the most widely distributed resource of the earth and unlike any other mineral resource, it gets its annual replenishment from the meteoric precipitation. The world's total water resources are estimated as 1.37 x 106 million ha-m. Of these global water resources, about 97.2% is salt water mainly in oceans and only 2.8% is available as fresh water at any time on the planet earth. Out of this 2.8%, about 2.2% is available as surface water and 0.6% as ground water. Even out of this 2.2% of surface water, 2.15% is fresh water in glaciers and icecaps and only of the order of 0.01% is available in lakes and reservoirs, and 0.0001% in streams, the remain- ing being in other forms. Out of 0.6% of stored ground water, only about 0.3% (41.1 x 104 Mha-m) can be economically extracted with the present drilling technology, the remaining being unavailable as it is situated below a depth of 800 m. Thus ground water is the largest source of fresh water on the planet excluding the polar icecaps and glaciers. The amount of ground water within 800 in from the ground surface is over 30 times the amount in all fresh water lakes and reservoirs, and about 3000 times the amount in stream channels, at any one time.