WATER HARVESTING
In Thar desert, indigenous systems that help preserve water are fast vanishing
Many water management systems are in disrepair due to encroachment in their catchment areas or a lack of knowledge on how to run them.
Rohit Jindal
Jelipa Nadi, with fresh intake of water after rains. Dungar Pir ji's temple can be seen behind. | Rohit Jindal via Mongabay
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The Thar desert on India's northwest periphery is full of challenges. Extending westwards from the Aravalli mountains, it is a vast expanse of sand, rocky outcrops, and scorching earth.
Daytime temperatures can reach 50 degrees Celsius, while rainfall is erratic and can be as little as 50 millimeters during an entire year. Yet, Thar is home to the highest human (and perhaps even cattle) density among any large desert worldwide.
It is also known for a wide variety of fauna in the wild, including the blue bull, blackbuck, Indian gazelle or chinkara, desert fox, and the great Indian bustard, among many others.
It is a fragile ecosystem where humans survived for centuries by building ingenious structures to preserve the most valuable commodity in this arid climate – water. Water was the currency in which the local economy operated. However, what took ages to develop is in rapid decline.
Many water management systems are in disrepair due to encroachment in their catchment areas or a lack of knowledge on how to run them. Reviving these traditional systems requires an understanding of their crucial role. Two such systems are the nadis and khadeens. While nadis can be seen in many parts of western Rajasthan, khadeens are more common in Jaisalmer.
The day time temperature in Thar desert can touch 50 degree Celsius, while rainfall can be as low as 50 millimeters during the entire year.Credit: Aiwok, CC BY-SA 3.0, via Wikimedia Commons.
Jaisalmer is the westernmost district in India, and area-wise, it is the largest in the province of Rajasthan. Almost all of its area lies in the arid belt of the Thar desert. Everywhere, there are large expanses of sand.
Jaisalmer was a trading post on the bustling silk route, serving as its southern artery. The 800-year-old local fort reminded travelers and traders on the silk route that there was a functioning kingdom with a firm grip on the local economy. India's independence and partitioning of the Thar afterward turned this area from the epicenter of a vast desert to the westernmost front of a newly born nation.
Water conservation in Thar
The question we must confront is: with the monsoon becoming so miserly by the time it arrives in the desert and with the absence of any perennial rivers in the area (even the seasonal Luni grazes the southeastern tip of the district), how did people survive here? How did the locals deal with this extreme scarcity of water?
The answer lies in the mindset of the people who considered water to be plenty once they discovered how to conserve it. Wherever rain fell, it was carefully diverted and used wisely; and when there was no rain, there was water to be harvested from the sub-surface recharge aquifers. So confident were the local masons in their skill that despite recurrent droughts, there were few famines.
While many of these traditional water harvesting structures now lie dilapidated, some are still functional even after centuries of use. An outsider can easily miss these, especially in the dry season when the gentle contours that lead to water diversion are hard to differentiate from what appears to be a flat landscape. Some structures store water to quench human and animal thirst, while others let the water percolate below the surface to allow a second crop during winter.
Nadis: The shallow pond
Nadis are shallow, artificial ponds that can store water for a few months to year-round. They are usually located in village grasslands known as orans and gauchars, making them part of mixed water-pasture regimes. For them to function well, these regimes need careful maintenance lest the water-holding impermeable layer of soil is breached.
Local rulers commissioned such nadis to retain water for human and animal consumption. They marked these nadis with stone pillars that carried information on when and how these nadis were constructed. Nadis are essential for maintaining the desert's economy.
Even after the construction of the Indira Gandhi Canal, far-flung villages rarely receive any water from the canal. These villages must depend on their old reservoirs to ensure water supply during the long dry months.
An old khejri tree in the Dunga Pir ji oran. Many such trees exist in orans next to the nadis and have cultural and religious significance for the local people. Credit: Rohit Jindal via Mongabay.
An example of such a nadi can be seen in Mokla village, 29 kilometers northwest of Jaisalmer on the Jaisalmer-Ramgarh highway. On approach to the village, one is presented with a sight to behold – a scrubby landscape interspersed with khejri (Prosopis cineraria) and ber (Ziziphus) trees. Much of this landscape in Mokla is part of Dungar Pir ji Oran, a sacred grassland extending to over 40,000 bighas (about 6,500 hectares).
Indeed, it is common to see herds of camels lazily browsing on khejri trees in the area. The oran has been with the village for centuries, and the local community is currently registering it with the district administration.
Most orans in Rajasthan are associated with a local deity, hence being revered as sacred. The Dungar Pir ji temple, located within Mokla's oran, is a small but imposing structure covered in white, with beautiful frescoes painted on its outer walls.
Next to the temple is a shallow pond or nadi, that stores water flowing in from a catchment that extends to several hundred hectares of the oran. It is the Jelipa nadi, and legend has it that it has existed for more than 800 years, as old as the Jaisalmer fort itself.
Trees in the orans slow the water runoff, hence more percolation of rainwater into the nadi. Nadis are a lifeline for cattle and even wildlife in remote areas with few water sources during the dry season.
Khadeens: low, muddy dams
A few kilometers from the Dungar Pir Ji oran is another ingenious water harvesting structure called khadeen (or khadin). At first, one only sees flat lands with some moisture visible on the surface. Away, in the distance, is a low, muddy dam (less than a meter in height) that extends to hundreds of metres. The dam and the upstream area around it constitute a khadeen, a centuries-old invention of the Paliwal brahmins of this area.
Khadeens are constructed on gently sloping lands with fertile topsoil, even if a non-porous, rocky layer is underneath. During monsoon rains, the low khadeen wall is a barrier to the flowing water. So, fields immediately behind the wall remain submerged during rains while those at a higher level upstream retain enough moisture for a good monsoon crop.
Come November, and if surface water is still in the catchment, sluice gates are opened in the dam to drain out excess water downstream. The area is now ready for a second winter crop, supported by the residual moisture in the soil. The result is a doubling (and sometimes even tripling) of the number of food crops farmers can take in the area. Earlier, khadeens were constructed only with earthen embankments, but nowadays, khadeens are constructed with cemented walls too.
A khadeen in Jaisalmer district. Residual moisture on the surface helps cultivate the winter crop. Credit: Rohit Jindal via Mongabay.
Khadeens irrigate thousands of hectares in the desert. But individual households only own small plots, so a khadeen is like a commune with an entire community able to support their agriculture-based livelihood. However, with the arrival of irrigation through borewells, and canal water, many of these khadeens are in disrepair.
While both khadeens are nadis are shallow structures that store water, how does one differentiate between the two? Khadeens are located on farmlands with occasional trees, nadis usually do not have any trees. Nadis can also carry water year-round, while khadeens are emptied at the start of winter to allow a second crop from residual moisture.
Both these structures can add to the area's resilience against dry climate when functioning well. But like endangered wildlife in the area, these ingenious structures constitute the vanishing equity of the Thar desert.
Rohit Jindal is an Associate Professor in the Department of Decision Sciences at MacEwan University, Edmonton, Canada. The story is based on the author's field visits to several traditional water management systems in the Thar desert in western Rajasthan.
This article was first published on Mongabay.
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