Ancient methods of Water Conservation
Introduction: Water which is one of the five essential elements, is a vital renewable natural resource. Three-fourths of the earth’s surface is covered with water and hence the name water planet and it is in the water where the origin of life can be traced.
Out of three-fourths’s water on earth, only 2.7% of it is fresh water that is fit for human consumption. Ice sheets and glaciers account for 70% of freshwater composting areas, but these are inaccessible for normal usage. Hence only 1% of fresh water available is fit for human consumption.
Rivers, lakes, and water vapor are some of the available forms of freshwater enabling man to use in an appropriate manner. Water is renewed regularly through the hydrological/water cycle in the form of precipitation.
Why do we need water?
Without water human survival is merely impossible, we need water to drink, bathing, cooking, washing clothes, and the food we eat needs water for its growth and productivity. On average, an Urban Indian uses 150 liters of water in a day. The multiple utility nature of water creates a huge demand for it.
Apart from human consumption, there is a huge demand for water in sectors like agriculture, industries, electricity generation (thermal power), etc.
Why does water need conservation despite being a renewable source?
Huge dependence and its overexploitation, water pollution which is the result of industrial waste deposition, depleting water table due to huge borewell diggings, mining activities and the availability of water is decreasing in the hands.
The scarcity of water can be seen in many parts of the world. Africa, West Asia, South Asia, parts of western USA, northwest Mexico, parts of South America, and entire Australia are affected by water scarcity.
Reasons for water scarcity:
➔ Seasonal variation
➔ Rainfall variation
➔ Overexploitation of water by industries
➔ Water pollution
Water Conservation in Ancient India:
In 21 st century we are still choosing the different methods that can be viable for water harvesting to counter the problem of scarcity and floods. The practice of water harvesting had its existence from time immemorial. With the initiation of human settlement and agriculture, water conservation too had its initiation.
Later with the growing need for water, mechanisms to conserve water also improved. Water is treated and worshipped as God, rivers are worshipped
in the names of goddesses this shows the attribute given to water by our ancient society. In Puranas also see mention of Maa Ganga referring to the Ganga river as a mother too.
In Krishi parashara book there is a conversation between Narada muni and Dharmaraj one of the Pancha Pandavas where Narada Muni mentions the importance of farming, farmer group, and even irrigation techniques and their need.
In Ancient India, water conservation was carried out to support irrigation, control floods, for drinking purposes and community use. Different dynasties and empires had different approaches to harvest the rainwater in a sophisticated manner far better than current techniques.
Empires and Water Harvesting Methods and techniques:
Indus Valley Civilization: The first urban civilization excavated in the India and Pakistan region, instead of being the oldest civilization had the best water harvesting techniques and best drainage system. Its water conservation technique can be appreciated in the Dholavira site, which reveals an intricate system of interconnected reservoirs, bunds, channels, drains, and check dams.
In Dholavira, Mansar stormwater channel and Manhar channel flowing in north and south respectively and to collect the monsoon runoff from these two channels 16 reservoirs were built between inner and the outer walls.
Mauryan Empire: One of the greatest empires of the Bharat also had great water harvesting methods. Ring well system for the first time appeared in the Mauryan kingdom to store water. Chanakya in his Arthasastra also mentions a water harvesting technique called Pynes and Ahars which is an interconnected network; Pynes which are water-carrying channels connected to the Ahars that are low-lying fields acting as reservoirs.
Famous Example: Sudarshan Lake (Saurashtra region) built-in Mauryan period again rejuvenated by Rudradaman in 1st century AD shows the importance of lake and water conservation.
Satavahana Empire: Introduced brick and ring wells to irrigate the agricultural lands.
Cheras and Pandyas: Patronized lakes and well irrigation. Irrigation tanks and structures acted as rainwater harvesting mechanisms.
Cholas: Introduced an advanced irrigation system. The great Anicut dam which was built by great Chola king Karaikal still exists in the Tamilnadu region, it is built on the Cauvery river to support irrigation and maintain the river stream.
Weirs were also important features, they are low head dams that act as barriers across the horizontal width of a river, they alter the flow of water.
Bhojtal: Built across Kolans river by King Bhoja in the 4th century which is known to be the largest artificial lake in India an earthen dam is also built on it.
Sringaverapura: A place near prayagraj had a good water harvesting structure built in 1st century BC comprising three percolation cum storage tanks to store floodwaters of river Ganga.
With time and generations, the techniques and methods underwent modernization, dobas, roof water harvesting, watershed models are some most prevalent techniques. Comparing the traditional and conventional water-storing systems the traditional systems tend to be more viable and lasting. Here are the differences between traditional and conventional techniques of water conservation/harvesting:
Were region-specific and were diversified. The system followed in Rajasthan or Bundelkhand region is not followed in the Ganga plains region
More localized and indigenous More modernized and materialistic.
Some Traditional and cultural water harvesting methods:
Kuls or Guls: Prevalent in mountain regions like Himalayan regions, these are surface water channels that carry glacier waters from rivers and streams into the fields.
Khadins: Found in arid and semi-arid regions, where agriculture fields are converted into storage structures, also called dhora it is a long earthen embankment that is built across the
hill slopes of gravelly uplands. It is indigenous to the Jaisalmer region and similar to the irrigation method of the Ur region present in Iraq.
Johads: They are also found in arid and semi-arid regions, where small earthen check dams are used to conserve and recharge groundwater, mostly constructed in naturally high elevated areas.
Phad: A community-managed irrigation system in the Tapi river basin in Maharashtra. In this system check dams built across the river and canals to carry water to agricultural blocks with outlets to ensure excess water is removed from the canals.
Zing: Prevalent in Ladakh, these are small tanks that collect the water from melting glaciers through a network of channels.
Zabo or Ruza System: Practised widely in Nagaland. Pond-like structures created on the terraced hillsides where rainwater from the hilltop is collected through channels of water.
Jackwells: Shopmen tribe of Great Nicobar widely uses this method where bamboos are placed under trees to collect the runoff water from leaves and carries it to jack wells which are pits encircled by bunds made from logs of hardwood.
Pat System: Developed in Madhya Pradesh, in this system water is diverted from hill streams into irrigation channels by diversion bunds.
Eri system: It is also one of the tank systems widely prevalent in Tamil Nadu, it is a flood control mechanism that prevents soil erosion and wastage of runoff during periods of heavy rainfall, and also recharges the groundwater.
Panam Keni: Followed by the kuruma tribe native to Wayanad, who uses wooden cylinders as a special type of well, which are made by soaking the stems of toddy palms and immersing them in groundwater springs.
Jhalara: These are typically rectangular-shaped stepwells that have tiered steps on three or four sides in the city of Jodhpur.
Kund: This is a saucer-shaped catchment area found in the sandier tracts of western Rajasthan and Gujarat that gently slopes towards the central circular underground well.
Bawaris: These are unique stepwells found mostly in Rajasthan and are part of an ancient network of water storage. The water received in that region is diverted to man-made tanks through canals built on the hilly outskirts, then diverted water percolates into the ground, raising the water table and recharging the deep groundwater and intricate network of aquifers. In order to
reduce the evaporation loss a series of layered steps were built around the reservoirs to narrow and deepen the wells.
Chand Baori is the famous and one of the biggest stepwells in the world and it was built by King Chanda in the 9th century.
Rooftop Rainwater Harvesting: It refers to the collection of rainwater from the roof surface and redirecting that water into a tank, deep pit, aquifer or reservoir with percolation through pipes in order to restore the groundwater.
In general, the practice is carried through a process,
- Collection of rooftop rainwater using PVC pipe
- Filtration using sand and bricks
- The underground pipe takes water to the sump
- Excess water from the sump is taken to the well
- Water in the well recharges the underground
- Water can be fetched from the well if needed.
Need for Rooftop Water Harvesting:
➔ Most of the Indian agriculture is rainfed and a huge number of population is depending on only a few water sources and this creates an imbalance between demand and supply.
➔ The average annual precipitation range in India is between 750-1500mm and the distribution of rainfall is uneven due to diversified geographical regions.
➔ Shortcomings in rainfall from the last decade are also creating worry among farmers. ➔ Flash droughts phenomenon.
➔ Water intensity crop plantations.
➔ Water scarcity and water stress conditions due to a reduction in groundwater level ➔ Pollution in freshwater due to both domestic waste and industrial waste are some of the reasons that are inducing the need to harvest roof water.
Some existing Rooftop Rainwater Harvesting Mechanism:
Tankas/ Tanaka/tanks(Rooftop Harvesting Mechanism): These are found in arid and semi-arid regions of Rajasthan especially indigenous to the Thar desert region. Tankas are well-developed rooftop rainwater harvesting, it is a cylindrical paved underground pit into which rainwater from rooftops, courtyards, or artificially prepared catchment flows.
Shillong in Meghalaya practices rooftop water harvesting widely though it receives the highest rainfall (as it is near to cherrapunji and mawsynram) as it faces an acute shortage of water. Nearly 15-25 percent of household requirements are fulfilled by this water.
Gendathur, a remote village in the Myusuru region of Karnataka also adopted a rooftop water harvesting mechanism. More than 200 households adopted this system. It receives annual precipitation of 1,000 mm and 80 percent of collection efficiency in that region.
Tamilnadu became the first state in India that made the rooftop water harvesting mechanism structure mandatory.
The storage differences between southern and northern India are:
No huge difference can be found between them, but compared to northern states the southern states and western states are facing huge water stress, due to arid and semi-arid climates, in the north as we discussed earlier many traditional systems are prevalent. In southern parts, small lakes, tanks, community ponds (cheruvu) are widely constructed, at individual level deep wells are constructed using bricks at farmlands.
Rather than step-wells small water systems with step models called Konerus are constructed at temple sites.
With the above discussion, we can get an idea of how water has been given importance at different ages and stages of history. The current generation and rapid development ignored the importance of conserving water resources. An environmentally friendly nature is required to counter this issue and it can be achieved through integrating old methods and new innovations to construct viable and lasting water conservation structures.