Tradition of groundwater prospecting in Himalayas

Survival in the mountainous terrain, with scarce water availability despite ample rains, would not have been possible without mastering the art of water harvesting. The people of the region therefore observed natural processes related to water, ensured this knowledge being transferred from one generation to other, and experiemented to maximise water availability.

Seeking answers to their inquisitiveness  related to (i) sudden appearance of seepages along the hill slope, (ii) fluctuations in the yield of these seepages with precipitation or changing season, and (iii) presence of seepages on certain slopes, these people deciphered the intricacies of hydrology, and Hydrological Cycle that laid the foundations of a sound tradition of water management in the region.

It was based on their keen observation, experience, experimentation, and accumulated knowledge of generations that these people understood:

• Water flows from higher to lower elevation.
• Rainwater percolates below the ground under favorable conditions.
• Rainwater is stored in underground reserves for long durations, and released slowly.
• Volume of water percolating below the ground is a function of the duration for which water stays on the surface.
• Forest cover promotes infiltration of rainwater to underground reserves.
• Measures to retain water at higher elevations for longer duration enhance groundwater reserves, and hence productivity of the downslopes seepages.
• Water percolating underground, and stored in underground reserves oozes out along the hill slope at places having some advantageous disposition.

After this it was not difficult for these people to conclude that at places where water was not visible on the surface it must be somewhere below the ground.

With this knowledge started groundwater exploration, and exploitation quest of these people.

But then this was not at all that simple, and straight forward, and from mere knowledge of the presence subsurface water to mastering the art of harvesting the same was a long drawn, and tedious journey marked with numerous failed attempts, and untiring pursuits.

It is important to understand out here that in the hills the groundwater is not evenly distributed below the surface as you would have experienced in the plains where water table is generally close to the surface, and at around similar depth from the surface at all places in a given geographical area. This makes groundwater exploitation relatively easy in the plains; dig anywhere for a certain depth, and you are sure to find water.

The situation is however not that simple in the Himalayas, where structural, and geological complexities make groundwater exploitation quite tricky, and challenging. General presence of two or more set of penetrative joints, and fractures in the rocks of the terrain that are attributed to the orogeny; continental collision, and ensuing metamorphism, shearing, folding, faulting, and fracturing of the intervening sediments, promotes underground dissipation of precipitation through numerous different routes that are hard to follow precisely even today.

Moreover unlike plains, there exists no permanent water table in the mountainous terrain, and for exploiting subsurface water one has to be precise enough to hit the perched water bodies that occur locally under favourable geological conditions, and do not have large spatial continuity.

You would better appreciate this if you review the efforts being put in presently by the state to install hand pumps in the hills for exploiting the groundwater. Remember that these also exploit the perched water bodies, and for enhancing the success rate the location of the drilling sites are finalised after detailed groundwater prospecting done by a multidisciplinary team of scientists, and researchers on the basis of geological, and hydrological investigations, and use of satellite remote sensing data. You would better appreciate the acumen of these people if you believe or know that even after the use of state of art scientific, and technical knowledge, and tools not all drill sites result in productive wells.

One needs to understand that despite the knowledge of water being present beneath the ground it was not possible to dig randomly at any place unless one has some clue of the depth at which water is to be encountered together with the expected discharge. But for this, the water-prospecting quest could result in trail of futile attempts that these people could hardly afford as their productive time was generally constrained by sunlight, and they had to take care of a number of chores just to survive, and make ends meet.

Having experienced growth of vegetation around water sources or  dhara these people came to know that the presence of water promotes vegetal growth. Furthering this premise these people correlated the presence of groundwater with the abundance of vegetation on the surface. In the process they also identified some specific plants that were particularly associated with favourable groundwater conditions. At the same time these people observed particularly good vegetal cover along concave slopes of the valley, and presence of seepages particularly around break in slope along the valley profile.

So, despite constraints put forth by the physiographic, and geological condition these people taking clues from geomorphic, and vegetation distribution pattern, and correlating these with known occurrences of seepages developed an algorithm for identifying prospective locations where water could be found at shallow depth.

Naula

Using their water prospecting algorithm these people slowly mastered  the art of locating perched water bodies in the mountainous terrain. Using their acumen they could dig at suitable sites, and reach the perched water body. This was however not the end of the quest. Much more was yet to be thought of, and done to use this water efficiently, hygienically, and conveniently.

To avoid the water getting spoiled by surrounding soil these people initially lined the walls of the dig hole or depression with stones. This at the same time provided stability to the walls of the depression. This was refined and improved with passage of time, and finally took the shape of flight of stone lined flight of stairs. This structure was convenient for water exploitation, and use.

These structures are identified as naula in local parlance.

Technically speaking naula is a shallow dug well generally 5 – 6 feet deep, and square in shape. Flight of stone lined stairs descend from all the four sides to the floor of the naula, and water seeping in from all the sides gets collected in the stone lined depression so created. These structures invariably have a stone lined sloping roof for protecting the water from getting contaminated.

Inside the structure little above the level of water there is a provision for placing the sacred lamp. Figurines of some local deities are also often placed there or else stones used for the construction of naula are ornately sculptured, and figurines of the deities along with other floral motifs are carved on these.

Outside this structure a stone lined outward sloping platform was created for diverse purposes, and special care was taken to ensure that the used water does not contaminate fresh water in the depression.

Kua

Using their accumulated knowledge of generations acquired by keen observation of nature, and experimentation the people living in rugged Himalayas developed an objective algorithm for narrowing their search of suitable sites for groundwater exploitation, and mastered the art of naula construction.

It is important to note that this quest of these people to exploit subsurface water had an important bearing upon the growth, and expansion of human presence in the mountainous terrain.

These people were however not satisfied with the exploitation of shallow aquifers alone. Armed with their ingenuity they devised techniques of identifying, and exploiting deep aquifers in this geologically complex terrain. Existence of baked brick lined kua or deep dug well on the ridges at Almora, and Nagthat stand testimony to their skill of locating particularly deep aquifers.

Construction of these deep wells could have never been possible without means for assessing the water yielding potential of the deep seated localized perched aquifers with high degree of accuracy.

Moreover unlike the plains, mountainous terrain does not have permanent water table, and subsurface water in the hills can only be exploited from perched water reserves that have limited geographical continuity. One cannot therefore be assured of striking a water-bearing horizon in the hills after digging a certain depth. Success at the same time can not  be guaranteed merely based on the experiences gained at one place, and mere replication of that at another place in the hills.

Development of an accurate and precise methodology or technique was therefore a precondition for exploiting deeper reserves of water.

No oral or written evidence of the methodology used by these people for water prospecting is presently available. The presence of deep wells in this geologically challenging terrain, and that too on the ridges definitely suggest that the people of the region had developed, and mastered the art of ground water prospecting.

One can only guess if they were using something akin to Y – sticks for this as both the technique used, and the means resorted for ensuring its conservation, and passage over generations have been completely lost.

This achievement of the people of the Himalayan region is however fascinating as even with all technological support of present times exploiting ground water in this region has not yet been error free despite huge technological, and financial inputs.

Deciphering the water prospecting technique of the people of the Himalayan region is a challenge for the researchers, and this quest might bring forth a major breakthrough in efficient water utilisation in the Himalayas.

The efforts of the indigenous people to explore, and exploit groundwater in this tectonically highly disturbed terrain therefore need appreciation, and applause.