In the sandier tracts, the villagers of the Thar Desert had evolved an ingenious system of rainwater harvesting known as kunds or kundis. Kund, the local name given to a covered underground tank, was developed primarily for tackling drinking water problems. Usually constructed with local materials or cement, kunds were more prevalent in the western arid regions of Rajasthan, and in areas where the limited groundwater available is moderate to highly saline. Groundwater in Barmer, for instance, in nearly 76 per cent of the district's area, has total dissolved salts (TDS) ranging from 1,500-10,000 parts per million (ppm). Under such conditions, kunds provided convenient, clean and sweetwater for drinking. Kunds were owned by communities or privately, with the rich having one or more kunds of their own. Community kunds were built through village cooperation or by a rich man for the entire community.

The first known construction of a kund in western Rajasthan was during 1607 AD by one Raja Sursingh in village Vadi-ka-Melan. In the Mehrangarh Fort in Jodhpur, a kund was constructed during the regime of Maharaja Udai Singh in 1759 AD. During the Great Famine of 1895-96, construction of kunds was taken up on a wide scale. It is quite possible that kunds could have been built even prior to 1607 AD in the villages of western Rajasthan. Jalwali, a village on the road from Bikaner to Anupgarh has nearly 300 kunds. Since the area is sandy, kunds have been constructed wherever the land slopes. Each household owns four to five kunds. Before the onset of rains every year, meticulous care was taken to clean up the catchment of the kunds. Cattle grazing and entry with shoes into the catchment area of the kunds was strictly prohibited. The proximity of a kund to the house or village saved time and effort in searching for drinking water. Without a kund, households in many parts of the Thar would have to make a 10-15 km round trip with a donkey, camel or bullock cart to meet their water needs. Coupled with the benefits of cleanliness and quality of water, the kund became an ideal device to collect drinking water. Water-borne diseases, which are otherwise quite common in the desert area, are thus reduced.

The kund consists of a saucer-shaped catchment area with a gentle slope towards the centre where a tank is situated. Openings or inlets for water to go into the tank are usually guarded by a wire mesh to prevent the entry of floating debris, birds and reptiles. The top is usually covered with a lid from where water can be drawn out with a bucket. Kunds are by and large circular in shape, with little variation between the depth and diameter which ranges from 3-4.5 m. Lime plaster or cement is typically used for the construction of the tank, since stone as a building material is not always available and is relatively more expensive. Either of these materials can be used to plaster the horizontal and vertical soil surfaces, although cement ensures a longer life span. The success of a kund depends on the selection of the site, particularly its catchment characteristics. An adequately large catchment area has to be selected or artificially prepared to produce adequate runoff to meet the storage requirements of the kund.

The catchment size of kunds varies from about 20 sq m to 2 ha depending on the runoff needed and the availability of spare land. A 2 ha catchment area, having a 2-3 per cent slope on a heavy textured soil free from vegetation, is generally sufficient for a kund of 200 cubic metres (cum) capacity. The catchment areas of kunds were made in a variety of ways using locally available sealing materials such as pond silt, murrum, charcoal ash, and gravel. After clearing the soil surface of vegetation, the land was given a smooth gradient of 3-4 per cent towards the kund and the cleared surface was lined with pond silt obtained from nearby talabs or nadi beds. A local technique was used after the first shower of the monsoon season to make this layer semi-permeable. In places where a calcium-carbonate zone was availabl e below the soil surface at a shallow depth, water-proofing of the soil was done with murrum. After clearing the soil surface of vegetation, a thin layer of murrum was spread over it. With the onset of the monsoon, sheep and goats were made to move over the murrum repeatedly till the surface was compacted and became semi-impermeable.

During this process water was also sprinkled, if needed. Although charcoal ash was not used as a surface sealing material by itself, it was used to repair the catchment area made of pond silt and murrum. As the ash settled down, it filled the pores making the surface water-proof. In certain areas, where rock exposures occurred, kund catchments were made of gravel layers. Such catchments were, however, very few, depending on the availability of gravel. The benefits of kunds during inadequate rainfall have been in doubt. However, a study which analysed daily rainfall records for 14 years in three or four raingauge stations in each of the 11 desert districts of Rajasthan puts these doubts to rest. It was calculated that there was effective rainfall (25 mm) on at least four to six days every year, except in Jaisalmer, Pali and Sikar. With this rainfall, a kund with a catchment of 100 sq km could easily collect 10,000 litres of water. Kunds with a diameter of 56 m and a catchment area of 2,463 sq m will bring in 246,000 litres of water. Even if we assume that only 40-50 per cent of rain will turn into runoff, a kund can still store 0.1 million litres of water.

The rainfall data collected showed that areas with 100 mm of rainfall can use the kund system effectively. Even if the kunds do not collect sufficient water they can be used as water reservoirs which can be filled by transporting water through water tankers. At present, tankers remain in the village till such time as the villagers have filled their pitchers, making numerous trips and losing a lot of time in the process. By filling the kunds, the tankers would need to make fewer trips as the entire kund could be filled up at one go.

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