Tuesday, March 25, 2008

Groundwater concept in ancient civilization

Groundwater concept in ancient civilization
By
Dr. Nitish Priyadarshi
Historical Background:
Our ancient religious texts and epics give a good insight into the water storage and conservation systems that prevailed in those days.

Groundwater development dates from ancient times. The Old Testament contains numerous references to groundwater, springs, and wells. Other than dug wells, groundwater in ancient times was supplied from horizontal wells known as qanats. These persist to the present day and can be found in a band across the arid regions of Southwestern Asia and North Africa extending from Afghanistan to Morocco. Qanats are laboriously hand constructed by skilled workers employing techniques that date back 3000 years.
Iran possesses the greatest concentration of qanats. Here some 22,000 qanats supply 75 percent all water used in the country. Lengths of the qanats extended up to 30 km, but most are less than 5 km. The depth of the qanat mother well is normally is 50 m, but instances of depths exceeding 250 m have been reported.
Some ancient Indian methods of water conservation:
The Indus Valley Civilization, that flourished along the banks of the river Indus and other parts of western and northern India about 5,000 years ago, had one of the most sophisticated urban water supply and sewage systems in the world. The fact that the people were well acquainted with hygiene can be seen from the covered drains running beneath the streets of the ruins at both Mohenjodaro and Harappa. Another very good example is the well-planned city of Dholavira, on Khadir Bet, a low plateau in the Rann in Gujarat. One of the oldest water harvesting systems is found about 130 km from Pune along Naneghat in the Western Ghats. A large number of tanks were cut in the rocks to provide drinking water to tradesmen who used to travel along this ancient trade route. Each fort in the area had its own water harvesting and storage system in the form of rock-cut cisterns, ponds, tanks and wells that are still in use today. A large number of forts like Raigad had tanks that supplied water. In ancient times, houses in parts of western Rajasthan were built so that each had a rooftop water harvesting system. Rainwater from these rooftops was directed into underground tanks. This system can be seen even today in all the forts, palaces and houses of the region. Underground baked earthen pipes and tunnels to maintain the flow of water and to transport it to distant places, are still functional at Burhanpur in Madhya Pradesh, Golkunda and Bijapur in Karnataka, and Aurangabad in Maharashtra.
Ground-water development and quality consideration were getting sufficient attention as evidenced by Vrahat Samhita (550 A. D.) Water management and conservation, well organized water pricing system in 400 B.C. Construction methods and materials of dam, tanks etc., bank protection, spillways and other considerations mentioned in the ancient books reflect the high stage of development of water resources and hydrology in ancient India.
Groundwater Theories in Ancient Philosophy:
Utilization of groundwater greatly preceded understanding of its origin, occurrence, and movement. The writings of Greek and Roman philosophers to explain the origins of springs and groundwater contain theories ranging from fantasy to nearly correct accounts. As late as the seventeenth century it was generally assumed that water emerging from springs could not be derived from rainfall, for it was believed that the quantity was inadequate and the earth too impervious to permit penetration of rain water far below the surface. Thus, early Greek philosophers such as Homer, Thales, and Plato hypothesized that springs were formed by seawater conducted through subterranean channels below the mountains, then purified and raised to the surface. Aristotle suggested that air enters the cold dark caverns under the mountains where it condenses into water and contribute to the springs.
The Roman philosophers, including Seneca and Pliny, followed the Greek ideas and contributed little to the subject. An important step forward, however, was made by the Roman architect Vitruvius. He explained that the now-accepted infiltration theory that the mountains receive large amounts of rain that perc olate through the rock strata and emerge at their base top form streams.
The Greek theories persisted through the Middle Ages with no advances until the end of the Renaissance. The French potter and philosopher Bernard Palissy (c. 1510-1589) reiterated the infiltritation theory in 1580, but his teachings were generally ignored. The German astronomer Johannes Kepler (1571-1630) was man of strong imagination who linked the earth to a huge animal that takes in water of the ocean, digests and assimilates it, and discharges the end products of these physiological processes as groundwater and springs. The seawater theory of the Greeks, supplemented by the ideas of the vaporization and condensation processes within the earth, was restated by the French philosopher René Descartes (1596-1650).
Dr. Nitish Priyadarshi
Geologist
Email: rch_nitishp@sancharnet.in
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