assignment on karez system and inundatin canal (about 8 pages)urgent
Answers
The Karez system of the Balochistan desert is a vibrant example of an ancient and still functional approach to community-based water management in an arid landscape. Karez irrigation technology was developed in arid and semi-arid areas from India and western China through the Middle East into North Africa. The technology is believed to have originated in the 1st millennium BC in Persia from where the knowledge travelled east and westward along the Silk Route, throughout the Muslim world, arriving in Xinjiang in China during the Han dynasty (206 BC – 24 AD) and in Balochistan somewhat earlier.
Traditionally, areas of population correspond closely to the areas where karez are possible. In this way the karez, its communities and their lands and pastures combine to form an organically evolved cultural landscape, rich in meaning and perfectly adapted to its harsh environment.
Karez are constructed as a series of well-like vertical shafts, connected by sloping tunnels, which tap into subterranean water in a manner that efficiently delivers large quantities of water to the surface by gravity, without need for pumping. The first well where the water is tapped for a karez is called the mother well, and there is a zone of roughly 1,200 feet in diameter where it is forbidden to dig new wells or otherwise threaten the quality and quantity of the groundwater. The vertical shafts along the underground channel are purely for maintenance purposes, and water is used only once it emerges from the daylight point.
Karez allow water to be transported over long distances in hot dry climates without loss of much of the water to evaporation. The system has the advantage of being resistant to natural disasters such as earthquakes and floods, and to deliberate destruction in war. Furthermore, it is almost insensitive to the levels of precipitation, delivering a flow with only gradual variations from wet to dry years. A karez is environmentally sustainable as it has no additional energy requirement and, thus, has low life cycle operation and maintenance costs.
Karez are owned and maintained by the community who buy shares in it or “shabanas”, 24-hour cycles. A karez, depending upon its size, may have anywhere from 18 to 32 shabanas distributed between its shareholders, with individual claims ranging from the right to a few minutes to a week of water. A shareholder, or shareeq, is entitled to the standing of a country gentleman in the community and may sit in a jirga and weigh in on collective decisions. In this way the system of water access, distribution and use is closely linked to social structures and community identity. Although a karez system is expensive to construct, its long-term value to the community, and thereby to the group that invested in building and maintaining it, is substantial.
Today, though the system is under threat, there are approximately 1053 functioning karezes in Balochistan having more than 22,000 lps discharge, irrigating 27,000 ha in 2012. Another 270 karez are not functioning but could be restored to use. They are located in the northwest corner of Balochistan bordering with Afghanistan and Iran. A group of four representative karez is being proposed for inclusion on the Tentative List:
Spin Tangi Kareze, District Quetta
Chashma Achozai Kareze, District Quetta
Ulasi Kareze, District Pishin
Kandeel Kareze, Muslim Bagh, District Killa Saifullah
Justification of Outstanding Universal Value
The karez cultural landscape of Balochistan represents the "combined works of nature and man", a living heritage tradition of great longevity in a harsh land where groundwater is vital to agro-pastoralist and sedentary agriculture. For more than a millennium karez have been the linchpin of groundwater tapping technology and part of a widespread technological adaptation characterizing the arid portions of the Muslim world.
The system illustrates the development of a communal technology, labour intensive but resilient and sustainable, in response to “the physical constraints and/or opportunities presented by their natural environment and of successive social, economic and cultural forces, both external and internal.” This cultural landscape has evolved organically and in the process has refined a perfectly balanced social and economic system that continues today to benefits both people and the landscape.
In rural Balochistan karez are based on community management; a community enterprise managed by tribal tradition and run by social control. While routine karez management and maintenance procedures kept the rural communities together through strong communal involvement, the drying of karezes strains those bonds. As karezes require considerable social organization for their maintenance, strong social capital undergirds the system.
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When the IBIS was developed, the drainage needs were initially minimal. Water tables were deep and irrigation water supplies were too low to generate much groundwater recharge and surface water losses. Whatever little drainage was required, could readily be accommodated by the existing natural drainage. The drainage needs, however, have increased as more irrigation water has been diverted and the water table has risen to harmful levels causing waterlogging and salinity. The drainage systems were developed over the last 30-40 years (Bhutta and Smedema, 2005).
Drainage and reclamation programmes to mitigate waterlogging and salinity, especially in areas where the water table is 0-1.5 m deep, have been assigned priority. Under the Salinity Control and Reclamation Projects (SCARPs), a disastrous area of 1.97 million ha (with a water table at 0-1.5 m) was reclaimed through rehabilitation of existing drains and investments for the new drainage schemes. Surface drains were also constructed in areas where surface runoff resulted from rainfall or excess irrigation. To encourage private sector participation in drainage, SCARP tubewells were transferred from the public to private sector. Tile drainage was given due attention. The current situation of the waterlogged area shows that the area at risk (with a water table at less than 1.5 m) comprises 12 percent of the total irrigated area. About 1.06 million ha of this area at risk has been covered under various SCARPs. During the current decade, an area of 1.21 million ha was reclaimed under drainage projects such as LBOD, RBOD-I, II and III, Drainage-IV and the National Drainage Programme with the installation of 1 260 drainage wells, transitioning of 5 000 public tubewells, construction or rehabilitation of 2 200 km of open drains, and laying of tile drainage system in 146 500 ha (MTDF 2005).
In 2008, the total drained area equipped for irrigation, was approximately 15.14 million ha.