Saturday, 7 November 2015

Traditional Water Conservation Methods in India

Rapid urbanization and water pollution has widened the supply and demand gap, putting enormous pressure on the quality of surface and groundwater bodies. Clean water is destined to become one of the rarest commodities soon, if the general public is not educated about the significance of storing, recycling and reusing water.

In India around 83% of available fresh water is used for agriculture. Rainfall being the primary source of fresh water, the concept behind conserving water is to harvest it when it falls and wherever it falls. The importance of storing rainwater through different techniques can be understood by an example of the desert city of Jaisalmer in Rajasthan which is water self-sufficient despite experiencing meager rainfall as against Cherrapunji, which is blessed with the highest rainfall in the world, but still faces water shortage due to lack of water conservation methods.

Water Conservation practices from past and present

Since ages, people across different regions of India, have experienced either excess or scarce water due to varied rainfall and land topography. Yet, they have managed to irrigate their agricultural fields using localized water harvesting methods. Their traditional ways, though less popular, are still in use and efficient. They are enriched with knowledge to manage water in communal ways. Let’s learn about a few traditional  water conservation methods in India used by our illiterate yet successful water managers in India.

Katta is a temporary structure made by binding mud and loose stones available locally. Built across small streams and rivers, this stone bund slows the flow of water, and stores a large amount (depending upon its height) during the dry months. The collected water gradually seeps into ground and increase the water level of nearby wells. In coastal areas, they also minimize the flow of fresh water into the sea.

It is a cost effective and simple method, used widely in rural areas. Series of stone bunds build one behind the other have proved to be more effective than modern concrete dams in some villages, as these local structures can be easily repaired by farmers themselves. Although they require many skilled laborers during construction, the cost is mostly shared by all the villagers as it is a common structure. However, with more people opting for personal borewells and handpumps, the water level in open wells has gone down severely, taking a toll on marginal villages. Thus, rejuvenating these community Kattas can go a long way in sustainable water management.

Sand bores provide a safe alternative for farm irrigation without affecting groundwater. This technique uses the concept of extracting water retained by sand particles. Sand particles act as great water filters by retaining the salt content at bottom and gushing pure water out. White sand is believed to yield water clean enough for drinking too.Sand deposits (as high as 15-30 feet) left along banks of rivers is dug using a manual soil cutter. Casing PVC pipes is inserted to act as filter and an electric or diesel motor is used to pump sweet water out.

The entire set-up costs around INR5,000-7,000 and requires less maintenance when sand deposits are fine and clean. The sand bore technique has been used in Karnataka since decades. The only drawback is that it can only be practiced in coastal areas or in areas with high sand deposits. The adjoining picture shows farmers preparing the PVC pipe filter with holes.

These water soak pits called as Madakas in Karnataka, Pemghara in Odisha and Johads in Rajasthan, are one of the oldest systems used to conserve and recharge ground water. Constructed on an area with naturally high elevation on three sides, soil is excavated to create a storage area and used to create a wall on fourth side to hold water. Johads collect monsoon water, which slowly seeps in to recharge groundwater and maintain soil moisture. Sometimes, many Johads are interconnected with a gulley or deep channels with a single outlet in a river or stream nearby to prevent structural damage. This cost-efficient and simple structure requires annual maintenance of de-silting and cleaning the storage area of weed growth.

Water from Johads is still been widely used by farmers to irrigate fields in many parts of India. In fact, the arid state of Rajasthan has seen a drastic improvement in water conservation due to the efforts of Rajendra Singh of Tarun Bharat Sangh to revive Johads. What needs to be done today is revival of old Johads, many of which have fallen into disrepair due to growth of weed plants and dumping of waste.

These step-wells are grand structures of high archaeological significance constructed since ancient times, mainly in honor of kings and queens. They are typically square shaped step-wells with beautiful arches, motifs and sometimes rooms on sides. Apart from storing water for basic needs, they at times also served for water sports.
Located away from residential areas, the water quality in these Bawdis is considered to be good for consumption. The typical lifespan of Jhalaras is around 20-30 years. Built with large investment of money and numerous skilled laborers, these magnificent structures today stand discarded by society.

Many of these structures have been encroached and act as mere dumping sites. Renovation of few of them in Rajasthan has restored their huge water storing capacity and with the use of electric pumps to draw water, it has proved useful during dry periods. Gujarat, Rajasthan and Karnataka have the maximum number of these structures, which attract tourists from all over the world.

Innovated by tribes of north eastern states, this technique economically uses water during dry seasons. It is practiced in hilly areas where construction of ground channels is not possible due to sloppy and stony terrain. This arrangement taps spring water to irrigate fields. A network of channels made by bamboo pipes of various diameters (to control flow), allows downward flow of water by gravity. An efficient system can reduce around 20 liters of inflow water running over kms to 20-80 drops per minute in agricultural fields.

Construction material such as bamboo and fiber is locally available. It is cost effective requiring less maintenance and only 1-2 laborers, who use tools to create a network of bamboo pipes to irrigate one hectare of land in 15 days. The system lasts for around three years after which the wood rots and decomposes to become nutrient-rich soil.

Farmers of Khasi and Jaintia tribes have successfully used this unique technique to irrigate fields of black pepper, betel etc. It has been replicated in urban areas too, where water stored on roof top tanks is flown through bamboo channels to irrigate fields and back gardens. Main advantage of the system is that it does not pollute like plastic counterparts and is very economical and simple to construct.

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