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Water Availability, Use and Management

Congress: 2008
Author(s):

Keyword(s): resource conservation technologies , supplement, Hydro-geological
AbstractPakistan is a country of over 141 million people, which is expected to grow to about 221 million by the year 2025. The most pressing need in Pakistan will be the management of the rapidly increasing population and provision of basic amenities of food, power and domestic water requirements. The Indus Plain, where most of the irrigated agriculture takes place covers about 202,000 km2 which is about 25.4% of the total land area. The Indus Basin Irrigation System commands an area of 14.64 million hectares and, as such, is the agricultural and economic centre of the country. The water resources available to the country are the natural precipitation, the surface water and the groundwater. In the arid to the sub-tropical climate of the country, the natural precipitation is scanty. Over half the country receives less than 200 mm of annual rainfall and rainfall in excess of 400 mm occurs only in about 20 percent of the northern areas. Apart from being scanty, the precipitation is distributed quite unevenly over the seasons and in a major part of the country this is concentrated in the 3 to 4 months of the summer monsoon. The sources of surface water available to Pakistan are its rivers. Most of these rivers, in the western half of the country, are ephemeral streams that remain dry for most of the year. It is the Indus river and its tributaries with perennial flows, that constitute the main source of water supply. The Indus River and its tributaries on average bring about 187 BCM of water annually. Most of the inflow, about 128.10 BCM is diverted for irrigation, 46.89 BCM flows to the sea and about 12.2 BCM is consumed by the system losses which include evaporation, seepage and spills during floods. The flows of the Indus and its tributaries vary widely from year to year and within the year. As is the case with the water availability there is significant variation in annual flows into sea. Water storage management in the Indus Basin Irrigation System comprises three major reservoirs, 16 barrages, 2 head-works, 2 siphons across major rivers, 12 inter river link canals, 44 canal systems and more than 107,000 water courses. The aggregate length of the canals is 60,376 Km. In addition, the watercourses, farm channels and field ditches cover another 1.6 million Km. The system also utilizes an estimated 51.3 BCM of groundwater pumped through more than 600,000 tube wells (mostly private) to supplement the canal supplies. The present water use for municipal and industrial supplies in the urban sector is of the order of 4.3 MAF (5.3 BCM). The demand is expected to increase to about 14.9 BCM by the year 2025. The total annual quantity of wastewater produced in Pakistan is 962,335 million gallons (4369 MCM) including 674,009 million gallons (3060 MCM) from municipal and 288,326 million gallons (1309 MCM) from industrial use. Disposal of untreated industrial and municipal wastewater has become one of the largest environmental problems in Pakistan. The groundwater storage capacity in Pakistan is estimated around 67.8 BCM. Hydro-geological conditions are mostly favorable for pumping by tubewells. It is estimated that 15,504 large capacity public tubewells and 469,546 private tubewells of low capacity are currently installed in the country. The groundwater pumpage in the Indus basin has increased from 4.12 BCM (3.34 MAF) in 1959 to 59.2 BCM (48 MAF) in 1996-97. Pakistanís groundwater resources are at the brink of exhaustion and there is a need to conserve this invaluable resource. Per capita water availability has gone down from 5104 cubic metres in 1950 to around 1200 cubic metres currently. Out of the 43 - 49 BCM going to the sea, a total of about 30.8 -37.00 BCM can be used for future development through construction of multi-purpose storages, remodeling of canals and irrigation extension schemes. There is little potential for increase in water availability for Pakistan from surface or ground water sources. In this context, several water conservation programmes are being implemented in different parts of the country. One of the measures for increasing agricultural output in rain fed areas of Pothwar Plateau in Punjab, Small Dams Organization has constructed 31 small dams in this area since 1961. These dams are designed to irrigate over 35000 acres. The water resources developed in the Pothwar region include 534 mini dams, 1087 ponds, 1612 dug wells, 172 turbine, 216 tube wells and 1568 lift pumps. The construction of 240 mini dams, 600 ponds and 1800 dug wells is under progress through Barani Village Development Project (BVDP). The resource conservation technologies (RCTs) that proved successful in Pakistan include watercourse improvement, LASER land leveling, zero tillage technology, bed & furrow irrigation system/bed planting etc. These techniques have been promoted on pilot basis for efficient utilization of water and non-water inputs for crop production. Various studies of watercourse improvement have revealed that on an average, annual water saving in an improved watercourse is about 100 Acre Feet besides other socio-economic benefits. Realizing importance of improvement of watercourses to check water losses Government of Pakistan has taken a mega initiative for improvement of all unimproved watercourses and the program envisages improvement of 86,000 watercourses in the country. Precision Land Leveling, another resource conservation technology, was introduced in the Pakistan during 1976-80 and about 500,000 acres have been precisely leveled so far. Initially, bucket type soil scrapers were used for precision land leveling, which have now been replaced by LASER beam guided automatic scrapers for more precision of land leveling work. Enhancement of water productivity at field level is the best option to redress water scarcity. Impact assessment studies conducted reveal significant benefits of water saving 20 - 30% and saving of area 5% through land leveling. Zero Tillage is an innovation that not only offers conservation of water and energy resources but also results in better crop yields (IWMI, 1999; OFWM, 2000). It was introduced in Pakistan during 1980ís. The technology was rapidly accepted by the farmers due to its potential benefits of 20 - 30% of water saving, 60% of energy saving, timely planting, increase in fertilizers use and 20% increase in yield. Wheat was grown with this technique on an area of about one million acres in Pakistan during 2003-04 and presently there are more than 5,000 zero tillage drills owned by farmers. Sprinkler and drip irrigation is one of the four basic methods of irrigating the crops. A sprinkler "throws" water through the air to simulate rainfall whereas the other three irrigation methods apply water directly to the soil, either on or below the surface. Government has started a mega project for the adoption of sprinkler and drip irrigation at large scale by providing heavy subsidy. These systems are getting popularity where water is scarce and topography is undulated.
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