“Simply put, swales are water-harvesting ditches, built on the contour of a landscape. Most ditches are designed to move water away from an area, so the bottom of the ditch is built on a modest slope, usually between 200:1 to 400:1. Swales, however, are flat on the bottom because they’re designed to do the opposite; they slow water down to a standstill, eliminate erosion, infiltrate the surrounding area with water, and recharge the groundwater table. When water moves along the flat bottom of a swale, it fills it up like a bathtub — that is, all parts of the bath tub fill at the same rate. The water in a swale is therefore passive; it doesn’t flow the way it would on a slope.”

“The swale system is self-regulating. Once the available water has reached an equilibrium, meaning it has filled the lowest point and has no where else to go, it just sits there, unmoving. And as it sits, it slowly seeps into the surrounding landscape, hydrating the soil and recharging the water table below. In this way, the swale fulfills three important functions: it carries water from the ditch to fill the dam, it rehydrates the landscape, and it prevents the dam from overflowing by acting as a channel back to the ditch. Swales are great for filling dams anywhere except for arid or hyper-arid environments, where they would dry up too quickly.”

“The mounds along the swale can provide enough water to establish a tree system with little to no additional irrigation. Conventional wisdom says that you need more than 15” or 381 mm of annual rainfall to establish trees. This is not necessary when you design a swale system to aid with water catchment, because it effectively concentrates and holds the available water in that area.”

Read more: Swales: The Permaculture Element That Really “Holds Water”. Picture: SUDSnet.

Previously:

• Water Johads: A Low-Tech Alternative to Mega-Dams in India.
• Precolombian Causeways and Canals.
• Water Batteries for Trees.
• DIY Glaciers: a Low-Cost Alternative to Dams.

When the British colonized India, they imposed their own system of water management, which included the building of large-scale dams, sewers, and irrigation channels. This high-tech approach continues today, as the World Bank is urging India to build enormous dam projects to fight drought and depleted aquifers. The Indian government has followed its advice. Its first Prime Minister, Jawaharlal Nehru, called dams the “Temples of modern India”. Since then, India has built over 5,000 dams and large reservoirs. [1]

However, before the British arrived, people on the subcontinent used traditional low-cost, low-tech engineering to collect rainwater for thousands of years. This involved the placement of thousands of small structures throughout rural areas which, in one way or another, catch excess rainwater from the monsoon months and allow it to slowly percolate into the groundwater during the dry season. To maintain and manage these structures, community-based management schemes were necessary. However, these were actively discouraged during British rule and following independence. As a result, in the 20th century many of these small reservoirs fell into disrepair.

In the 1980s, the Alwar district in the North-Western state of Rajasthan was one of the driest in all of India, even though older villagers remembered that its rivers used to flow in the past. Many farmers were migrating to the cities, as there was no longer any means of subsistence from the land. In 1985, Rajendra Singh—now known as the ‘Water Man of Rajasthan’—arrived in the area and started encouraging villagers to rebuild their old water reservoirs, or water johads. When the villagers had constructed 375 johads, the river began to flow after having been dry for several decades. [2]

By 2003, Singh, through the NGO Tarun Bharat Sangh, had helped with the construction of over 5,000 johads and the rejuvenation of 2,500 old reservoirs, providing irrigation water to 140,000 ha. and 700,000 people. [3, 5] In 2015, 8,600 johads had been built, bringing water back to 1,000 villages. [4] The johads are incredibly cheap and productive—at 100 rupees per capita, they can raise economic production by as much as 400 rupees per year. Compare this to nearby Sardar Sarovar Dam project, which cost 300 billion rupees, and cost 100 times more per person supplied with water, and 340 times more per hectare irrigated. [3]

The design of water johads. Source: Anupma Sharma, National Institute of Hydrology

And yet water johads are extremely simple and low-cost structures that require no large equipment or expensive materials to build—simply a village of able hands and local elements. After digging a pit, the villagers shape the excavated earth into a semicircular mud barrier. A stone drain is sometimes set up, allowing excess water to seep into the ground, or connecting it with johads nearby. Essentially the johad will capture runoff from monsoon floods and allow it to slowly percolate into the water table during the dry months. When many johads are built in one area, they have a cumulative effect, resulting in the replenishment of whole aquifers. [5] In addition, it has been shown that the water stored in the aquifers does not draw away water from communities downstream. [6]

It’s important to note that water johads are place-specific technologies and cannot necessarily be replicated to other geographical locations or climates. They require steady sloping land—where each johad can feed water into another downstream—and a rainy season, where floods can fill up the reservoirs during the dry months.

In addition, constructing and maintaining thousands of water reservoirs also required new forms of resource management. Since the government refused to participate with the johad construction efforts, or recognize that they were effective—its policies remain tied to the development narrative. Villagers decided to take matters in their own hands and organize their own water management councils, which have now expanded to managing forests and parks through participatory and democratic methods. The result is what some have claimed a miracle: bringing water back to a water-scarce and impoverished area.

Building Community

An engineer might look at a johad and claim that it is far too simple a technology—there is no innovation here, let alone a miracle. This is true: similar technologies exist all over the world. In Mediterranean countries, for example, rain water catchments were built over a thousand years ago and continue to provide water to farmers during dry seasons.

Rajendra Singh attributes the success of the johads to the fact that the technology encourages people to work together, building community while addressing essential needs. This is in strong opposition to the large government-built dams, which have displaced millions of people in India and, on average, have increased poverty. [5]

So, perhaps the key innovation with the johads is that rather than relying on engineering expertise or governmental action, villagers have constructed the johads themselves through traditional methods and community participation. The result is the revival of a low-tech tradition that is far more cost-effective than high-tech dams could ever be.

Aaron Vansintjan

Sources:

[1] International Commission on Large Dams (ICOLD). http://icold-cigb.net/GB/World_register/general_synthesis.asp?IDA=206

[2] The Water Man of Rajasthan. Frontline. Sebastian, Sunny, 2001.

[3] Water-harvesting in India transforms lives. Alternet. McCully, Patrick. 2003

[4] An ancient technology is helping India’s “water man” save thousands of parched villages. Ghoshal, Devjyot. 2015.

[5]. Water Harvesting: Alwar, Rajasthran. National Institute of Hydrology (Roorkee, India). Sharma, Anupma.

[6]. Traditional Water Harvesting Structure: Community behind ‘Community’. Economic and Political Weekly. Vol. 41, No. 7, pp. 596-598. Kashwan, Prakash, 2006.

[7]. “Dams,” The Quarterly Journal of Economics, MIT Press, MIT Press, vol. 122(2), pages 601-646, 05. Esther Duflo & Rohini Pande, 2007.

Related: Madakas.

“Soil and plants are placed in the outer donut-shaped chamber, and the center chamber is filled with water. The unglazed terracotta’s natural porosity allows the water to move from the center chamber and into the soil, based on the soil’s moisture (and thus the plant’s need for water). The terracotta wall both regulates and filters the water. A simple lid on the top of the water chamber prevents evaporation.”

The design is based on the Olla, a terracotta pot for irrigation that has been in use for 4,000 years. See also:

• Botijo’s: how to keep beverages cool outside the refrigerator
• Ceramic food steamer with central chimney
• The poor man’s refrigerator
• How to make your own low-tech vertical farm

“Using groundwater to grow crops and trees doesn’t make sense to Pieter Hoff, a Dutch inventor. Not only are traditional irrigation techniques inefficient because most of the water is lost to evaporation, Mr. Hoff says, but water can be easily captured from the atmosphere to grow just about anything.

To prove his point, Mr. Hoff retired from the lily and tulip export business in 2003, established his company, AquaPro, and devoted himself to the development of the Groasis Waterboxx (manuals), which he says will grow food crops and trees even in the driest places on earth.” Read more.