Traditional harvesting system is a useful system to conserve and store water." highlight the importance of this system with two example
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Sand Bores
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.
Madaks/ Johads/ Pemghara
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.
Bawdi/Jhalara
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.
Bamboo Drip Irrigation
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 labourers, 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.
Rooftop Rain Water Harvesting
All of us who directly consume water are the most important stakeholders in managing water. While many of us urbanites use or waste a lot of water, we rarely make an effort to conserve it. Fortunately, the rainwater harvesting method has provided a solution that can be practiced easily in every household. It is a simple model where the roof acting as a catchment for rainfall, which after flowing through a series of filters and pipes is stored in ground-level containers for direct use or recharged into ground water. Given below is a simple formula to calculate the water that can be collected from your rooftop.