KHADIN - THE TRADITIONAL WATER HARVESTING SYSTEM

A khadin, also called a dhora, is an ingenious construction designed to harvest surface runoff water for agriculture. Its main feature is a very long (100-300 m) earthen embankment built across the lower hill slopes lying below gravelly uplands. Sluices and spillways allow excess water to drain off.

PRINCIPLE -The khadin system is based on the principle of harvesting rainwater on farmland and subsequent use of this water-saturated
land for crop production

First designed by the Paliwal Brahmins of Jaisalmer, western Rajasthan in the 15th century, this system has great similarity with the irrigation methods of the people of Ur (present Iraq) around 4500 BC and later of
the Nabateans in the Middle East. A similar system is also reported to have been practised 4,000 years ago in the Negev desert, and in southwestern Colorado 500 years ago.

Sensing and Geographical Information Systems can help in the determination of areas suitable for water harvesting (Prinz et al. 1998).Khadin- A traditional successful water harvesting system in India Khadin is an ancient skilful and sound scientific example of rainwater harvesting system in Western Rajasthan/ India.

STRUCTURE - A Khadin is an earthen embankment built across the general slope which conserves the maximum possible rainwater runoff within the agricultural field. The size of the Khadin is designed on the basis of local rainfall patterns, catchment characteristics and soil type. On an average, the cultivated area under each Khadin is 10-14 ha with an average dam size between 1.2-1.7 m high x 1.0-1.5 m wide and 100-300 meters in length, depending upon catchment area and number of land holdings. The spillways and sluice gates are usually provided at a proper location for excess water during flood conditions. The embankment not only helps to increase moisture in the submerged land, but also prevents the washing away of the top soil and the manure added to it.
For efficient agriculture, a minimum of 15:1 ratio of catchment area to crop area is required. A rainfall of 75-100 mm is sufficient to charge the Khadin soils with sufficient soil moisture content to raise a successful local crop. In the Khadin area, the collect runoff percolates into the ground with time recharges the subsoil.Of the total runoff collected only 50-60% of the water is utilised. The remainder is lost to evaporation, or percolates into the underground, recharging an aquifer.
Depending upon the amount of rainfall and consequent runoff received during the monsoon, one or two crops are grown. There is 3-4 fold increase in agriculture production, in comparison with non-Khadin conditions depending upon rainfall quantity and distribution. This system assures the farmers of at least one crop even in very dry tracts. The construction cost for single Khadin ranges from US $ 125-175. This construction cost can be repaid back within three to five years. Other than improving socio-economic conditions of desert dwellers, Khadins also have created positive impact on the ecology of the region, effectively checking soil erosion and increasing vegetation cover.