Traditional irrigation and water distribution system in Ladakh

Abstract

Ladakh constitutes the easternmost trans-Himalayan part of Jammu and Kashmir state, bordering Pakistan and China (Fig. 1). Described as cold arid desert, it covers an area of 59146 sq km situated at an elevation varying between 216-420 m above sea level along the valleys of the Indus river, with an estimated population of 1,70,541. Intensive sunlight, high evaporation rate, strong winds and fluctuating temperature characterize the general climate. Vegetation is sparse, rains are very rare, and most of the land is a mountainous desert of rocks, sand and dust. Only small parts are used for cultivation and animal husbandry through terraces and irrigation canals. Because of high mountains all round and heavy snowfall during winter, the area remains inaccessible to the outside world for nearly six months in a year. Irrigation technology in Ladakh was transferred from neighbouring regions. The farmers have made use of the barren alleviated semi desert conditions by cultivation through skillful irrigation; said to have been introduced in tenth century. Since the streams run away from cultivable land or are incised deep below to bring a long canal, it requires considerable traditional expertise. The bed of the canal is often made of very porous material, loose stones and boulders, so there is considerable loss through seepage. The Stongde Gompa (in Zangskar valley of Ladakh) canal loses nine/tenths of the initial flow of 0.01 m/sec before reaching the Gompa. Wherever it is possible farmers have skillfully canalized the water through construction of long canals, some of them running over few kilometers traversing through rocky mountains. These canals were constructed in a very early stage of the history of the region. The melted snow water from various rivulets, called kangs-chhu (ice water) merging at some point forms a togpo (stream), that flows through a valley touching many villages connected by a main channel, called ma-yur (mother channel). It is built along a mountainside that forms its retaining wall, and is lined with clay to hold the water. This is termed the Ladakhi version of a dyke. At some places rocks are broken to allow the passage of water or else where the rocks are too hard, a hollow poplar or willow trunk, called va-to is cut into two equal halves to allow the water easy passage. Water from the ma-yur is further diverted into yu-ra (small canals), which irrigates the fields. The point from where togpo water is diverted into ma-yur, and ma-yur water into a yu-ra is called yurgo; and ska is the point from where yu-ra water is diverted to the field. Water in the ska is further guided through channels known as snang, which carry the water into the field.The water distribution through a system of channels is quite complex with different sizes of channels distinguished by various names (Fig. 1) as enumerated below: