“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.

Detail of an engineered landscape in the Bolivian Amazon. Artwork by Clark Erickson.

“In contrast to the Western obsession to drain what are considered marginal wetlands for agriculture, farmers in the Bolivian Amazon may have intentionally expanded wetlands and wetland productivity through earthwork construction, which impedes, rather than enhances, drainage.

The precolumbian farmers did not use causeways as dikes to prevent inundation of fields and settlements, but rather to expand and enhance inundation for agricultural production.

At the same time, impounding water with well-placed causeways and the creation of canals improved and extended the season of transportation by canoe across the landscape. The grid-like structure also permanently marked land tenure in a highly visible manner.”

“Causeways are flanked by canals on one or both sides where earth was removed to raise the road platform. Although badly eroded by cattle farming and farming activities, causeways are visible from the air as dark straight lines of trees and bushes that stand out against the grasses of the savanna.

Canals are marked by aquatic vegetation and standing water during the wet season and darker vegetation and soils during the dry season. Causeways range in elevation from 0.2 to 2 m  and in width from 1 to 20 m. Most causeways are straight over lengths ranging from tens of meters to kilometers.

Some of the most impressive causeways, canals, and raised fields are found on the Middle Apere River, [covering] an area larger than 60km2 along both sides of the river.”

Precolumbian causeways (wide white lines) and raised field blocks (thin white lines) overlaid on an aerial photograph.

“For the precolumbian peoples who built them, these earthworks would have significantly extended growing seasons and reduced agricultural risk. Instead of wholesale diversion of overbank flow from the river onto the levee backslope, the primary hydrological function of the causeways may have been to create local catchment areas where local rainfall and floodwater were harvested for agriculture and the period of canoe access to wetlands during the dry season was extended.

Throughout the year, access to the wetlands for fishing, hunting, and collection of aquatic resources was improved through causeway construction and impounding of water. The resulting expansion of seasonal wetlands on the levee backslopes also improved nutrient capture and production within the blocks of causeways.”

Quoted from: “Precolumbian Causeways and Canals as Landesque Capital” (PDF), Clark L. Erickson and John H. Walker, in “Landscapes of movement: Trails, Paths, and Roads in Anthropological Perspective”, edited by James E. Snead, Clark L. Erickson and J. Andrew Darling, University of Pennsylvania Museum of Archaeology and Anthropology Philadelphia, 2009.

“One winter in the late 1980s, an engineer from Skara named Chewang Norphel came up with a possible solution to his village’s problem while strolling around his backyard. Norphel noticed that a small stream had frozen solid under the shade of a poplar grove, though it flowed freely elsewhere in his sunny yard. The reason for this, he realized, was that the flowing water was moving too quickly to freeze, while the sluggish trickle of water beneath the grove was not. Over the next several years, Norphel worked to create an irrigation system that functioned using the same simple natural principle. The result has been Ladakh’s artificial glaciers. Ten
have been built to date.”

Read more: Artificial Glaciers Water Crops in Indian Highlands.

“A spiral pump, first invented in 1746, has been recreated and tested at Windfarm Museum using lightweight and inexpensive modern materials. A 6 foot diameter wheel with 160 feet of 1-1/4 inch inside diameter flexible polyethylene pipe is able to pump 3,900 gallons of water per day to a 40 foot head with a peripheral speed of 3 feet per second.

With its low torque requirements, the pump is particularly suited to be mounted on and driven by a paddle wheel in a current of two feet per second or greater. This easily built, low maintenance spiral pump can be used to provide water without the need for fuel wherever there is a flowing stream or river. It can also be hand turned or otherwise driven to provide a low cost, efficient pump.”

Read more: 1 / 2 / 3 / 4. Thanks to Paul Nash.

See also:

• Power from the tap: water motors
• Back to Basics: Direct Hydropower