How to manage scientificially?
By DR. S. M. ALAM, M. A. KHAN AND DR. R. ANSARI.
Nuclear Institute of Agriculture, Tandojam, Pakistan
Jul 03 - 09, 2000
Water is an important component of life. Allah has created every moving (living) creature from water (Surah 24, An-Nur, Ayet 45). We need about 15 glasses of water daily and human body contains about 60% of water. Without food we can survive for nearly 80 days, but only a few days without water. Fresh water for human and agriculture use is only 0.008 % on the earth. A shortage of fresh water is probably going to be most serious resource problem the world will face after a few years from now. As with food, the problem of water is not one of the global shortage, but one of uneven distribution. Three-quarters of the fresh water on the planet is held in the polar icecaps and glaciers and so is unavailable for use. Where water is plentiful, people are frequently few, and vice versa. The most water- rich country in terms of the run-off from rain-fall to population is Iceland, with more than 500,000 cubic meters per person per year; the most water- poor is Egypt, with just 0.02 cubic meters. Water is absolutely essential for plant life. Plants use more water than any other substances they absorb. The function of soil moisture in plant growth is very important. Excessive quantity of water in soil inhibits plant growth and makes drainage essential. When soil moisture is not enough drought, condition prevails leading to ultimate death of plants.
Many parts of the world are confronted with water scarcity, for both irrigation and human needs. Some 70 per cent of the water, people use goes to irrigation. Since 1950, the amount of irrigated land has tripled, and one-third of the world's food is grown on it. Without that increase, the world might now be starving. The great controversies over distribution of river water and construction of reservoirs, dams, barrages and link canals are very common among the various countries of the world. Providing water for irrigation and for cities will require damming more rivers, flooding more valleys, carrying out more giant water engineering schemes. Such projects are often hugely expensive and not only in economic terms. Large dams frequently involve massive changes in the use of land. That means not only the displacement of people from their homes but the loss of farm land, disturbance to water tables, build-up of silt, and other environmental costs. Of course dams also produce water for irrigation and for generating hydroelectricity, controlling floods, producing fish and even providing recreational facilities but serious attempts to measure the benefits from dams suggest that the gains are often smaller than the costs.
The disputes over the distribution of river waters are very common in the human society . Water resources often cross national boundaries, making it very easy for one country to 'steal' the water that should be delivered to another. No-one can predict which of several points of tension will result in armed conflict, but it is easy to list some candidates. They include, Threats to dam the upper Blue and White Nile; The diversion of water from the Sea of Galilee into Israel's National Water Carriers the Gabcikovo dam on the Danube in Slovakia; the damming of the upper reaches of the Tigris and Euphrates by Turkey and the Euphrates by Syria, distribution of water of river Ganges between Bangladesh and India, construction of dam on river Kavari between two southern provinces of India. The distribution of water's shares of Indus had been a source of conflict between India and Pakistan, but in 1959 an agreement was reached whereby the waters would be shared. These are the few examples of this scenario. All over the world, the lower riparians on rivers are usually complaining against the upper riparians for not giving their due share of water, but human nature prevails every where and results in disturbed situation. While there is no way of predicting whether these pressure points—or any of the other dozen situations around the world—will erupt into war, it is easy to see that control over water will come to be seen as a much more important strategic issue both between countries and within them.
The arid and semi-arid regions of the world have to depend on river water sources for their agriculture i.e. mainly on artificial canal irrigation system. The source of main water in Pakistan is canal irrigation system. The Indus valley, comprising the planes of Punjab and Sindh is mainly dependent on the water of river Indus and its tributaries, as the area is mostly arid on the basis of annual precipitation. The river Indus is the life line for Pakistan's agriculture. The nearly 450,000 sq.m. Himalayan watershed of Indus and its tributaries includes the world's biggest glaciers outside the polar regions. The Indus river rises from a lake named Manasarowar in southwestern Tibet at an altitude of 16,000 ft or 4,900 m and flows in a north westerly direction along the slopes of the Himalayas, travelling a distance of about 1500 miles) and crossing at north -west Jammu and Kashmir from the southwest. In west Kashmir it flows through a defile 13,000 ft deep. The river Indus is a great trans-Himalayan river of south Asia and one of the longest rivers of the world having a length of 18,00 miles( 2,900 km).The glaciers of Siachin (75 km), Baltro (62 km), Hispar (53), Biafo (50km), Shyok, Shingar, Hunza, Gilgit, Astor. These mighty glaciers and other streams with 30 tributaries constitutes a surface area of 1220 sq kms (471 sq miles ) carry snow melt waters to the Indus from the main Hamalayan range, the Karakoram range, the Nanga Parbat, the Kohistan ranges etc mostly in summer season . The river crosses the western Kashmir border and then turns south and southwest to enter Pakistan. In Pakistan, it emerges from the mountain highlands flows as a rapid stream between the Swat and Hunza regions and proceeds onwards through North- West Frontier region and crosses the salt range to enter semi-arid Punjab plains where it is joined by the Panjnad (near Mithankot). The Indus receives its most notable tributaries from the Punjab to the eastern sides, including Jhelum, Chenab, Ravi, and Sutlaj rivers. After receiving the waters of the Punjab rivers . Shifting to the south-west, the Indus becomes much wider and enters into the Sindh region near Kashmoor and then flows to a slow speed, depositing large quantities of silt along its course. Indus begins its deltaic stage (3,000 sq.m ) and breaks into distributaries that reach the Arabian sea at various points southeast of Karachi.
Water resources system is the life line for Pakistan. It is a source of life and energy. It is the most critical factor of production in Pakistan's agriculture. To increase agricultural production, land is not a limiting factor as there is more cultivable land available that can ever be properly irrigated. It is a universal solvent and cleanser. It has a very economic value, which is at a constant rise with population. Pakistan is arid to semi-arid country, located between the longitude 61° east to 76° east and between latitude 23° north to 37° north. Total area of Pakistan is 79.61 million hectares. Population of the country is about 150 million and nearly 75 percent it lives in the rural areas. Agriculture is the main stay of Pakistan's economy, contributing 35 percent to the gross domestic product and providing 60 percent of the labour force. Moreover, nearly 60 percent of the total export of the country originates from agriculture. Total annual cropped is about 19.72 million hectares. Out of which, 15.3 million hectares are irrigated areas, about 75 % (11.4 mha.) is irrigated through canals, l9 % (2.9 mha.) through tube wells 2 % (0.3 mha.) through wells and remaining 4 %(0.4 mha.) through tanks and other sources. Major crops grown are wheat, rice, cotton, maize and sugarcane which together make about 63 percent of the total cropped area. Production of three important crops. namely rice, cotton and sugarcane as well as 90 percent of wheat and most of maize is virtually confined to irrigated areas. The climate of the country is favourable for two crop's season under irrigated during the year.
In Pakistan, the total water supplies available to agriculture come from three sources rainfall, surface water from the River Indus and its tributaries, and the ground water, and also from sewage water and sea water. The mean annual rainfall varies from less than 100 mm in Sindh to more than 1000 mm in the foot-hills and northern mountains with an average of about 400 mm. About 60% of this rain comes during the monsoon season (July through September). Much of the summer rains are not available for crop production due to rapid run-off because of torrential showers. At other occasions, rain may be so light that the precipitation evaporates before the water can penetrate into the root zone. However, the contribution of rain to crops in the irrigated areas of Indus Basin is estimated at about 1650 thousand hectares meter. Thus 10 mm of rain water provides 100 cubic meter of water per hectare. Rainfall alone is inadequate to sustain more than a very low level of agricultural production in the semi-arid conditions which prevail over most of Pakistan. Ground water is the second major source for irrigation. The seepage through rainfall, rivers and vast canal network has created a large and readily manageable acquirer underlying the Indus basin. The total recharge to the groundwater system of the Indus Basin has been estimated at 56 MAF per annum. Presently, the ground water is being developed canal commands of Indus plain for the purpose of irrigation on the large scale and is of the order of 44 MAF per annum . There is a huge source of highly saline sea water along the 1,050 km coast of Pakistan along the Arabian sea, but it cannot be used either for drinking or irrigation unless desalinized. Some palm and coconut trees can be grown in coastal belt using saline water. With the extension of big cities and towns the quality of sewage water is increasing considerably. It is mostly used for the production of high value crops like vegetables, fodder, oil palm, coconut etc in the vicinity of cities and towns. However, there is a common belief that the vegetables raised from sewage water are not safe for consumption from hygienic point of view. Nevertheless, there is potential for treating the sewage water for recycling or using it for irrigation purposes as is being done in many other countries.
Irrigation system of Pakistan has been developed from the Indus waters more than hundred years ago and is now the largest integrated irrigation system in the world. The flow of Indus river system is the prime source of surface water resources of the country. It covers gross area of 16 million hectares of which 88 per cent is culturable. It has 48 principle canals, emerging out of 20 river diversion structures. Many of the canals are even large by world standard; 15 of them having capacities of over 280 cubic meter per second. The cumulative operating capacity of these canals is 7323 cubic meters per second and their annual conveyance capacity is 331 billion cubic meter. These canals traverse about 61,000 kilometers to command the 15.50 million hectares of culturable area through 90000 watercourses and filled channels numbering 1,07,000. Each watercourse serves about 160 hectares of land on the average. In addition, there are 23 barrages, 45 main canals, 12 huge inter river link canals transferring bulk water supplies from the western rivers to the eastern rivers.
Presently, Pakistan irrigation system encompasses two major dams such as (I) Mangla - The main technical features of this dam is as: World's third largest earth filled dam, built on river Jhelum; Height-380 ft. above river bed; Length 10300 ft. Gross water storage capicity-5.88 MAF, also used for Power generation; Live storage capacity -538 MAF; .Main spillway capacity -870,000 cusecs; Emergency spillway capacity 230,000 cusecs; Lake area- l00sq.miles, (II) Terbela- The main feature of this is as: The world largest earth and rock - filled dam on one of the world's most important river the Indus; Height- 485ft. above river bed; Length 9000 ft; gross storage capicity ,11.3 MAF; Live storage capacity- 9.4 MAF; service spillway capacity 6,50000 cusecs; Auxiliary spillway capicity- 840,000 cusecs; Lake area- 100 sq. miles. ,The Terbela dam is known as the best hydel power station in Pakistan having a capacity of generating 3,478 MW of electricity. The Chashma is the biggest reservoir which help in the irrigation of millions of hectares of agricultural lands.
In addition to the grand canal system, there are about 185,000 private tube wells with average capacity of 30 liters per second and about l5000 public tube wells of capacity of 60 to 120 liters per second. At present these tube wells pump about 41 billion cubic meters water and provide 30 per cent of the total irrigation water to exclusively more than two million hectares in addition to supplementing some canal fed areas. Water available at the farm gate after accounting farm losses and run-offs estimated that about 60% of water which comes to 35 MAF is lost during conveyance through canals, distributaries and water courses and also goes to Arabian sea at Karachi annually which is a huge national waste. This water must be harnessed if our posterity have to be saved from feminine like situation.
Total available water resources of the country from the rivers as well as fresh ground water come to 160 million acre feet (136 MAF from rivers i.e 94 MAF from Indus; 20 MAF from Jhelum and 26 MAF from Chenab ;and 24 MAF from fresh ground water sources). Out of this, 101.4 MAF reaches at the modules or the starting points of the watercourses, after deducting losses of the system, i. e seepage from the canal and distributaries, 35 MAF water was being wasted into the sea during flood season every year. Another available water 45 per cent is lost due to seepage from the water courses, which in absolute terms is 45.6 MAF, thus total water reaching at the farm gate remains about 56 MAF. About 15 percent additional water is lost due to improper irrigation applications, which in absolute terms is 8.4 MAF. The total requirement of the country in the year 2000 is estimated to be 78.7 MAF, which means that there is a shortage of 22.9 MAF at the farm gate for which there seems to be no supplementary source at present. Pakistan needed 170 million acre feet of additional water in future to meet irrigation and other requirements of the people. This was not possible unless new storage dams were built. India was planning to build Salal dam on the Chenab river and diverting the Indus river water from the Wooler lake in occupied Kashmir.
Conclusion
To overcome water shortage crisis, the solution lies in the proper water management at watershed, reservoirs, conveyance system i. e, at canals and distributaries level as well as watercourses and farm application levelling of open channels and use of pipes to transport water for reducing seepage losses. To prepare cemented water beds at the bottom of the base. Building of more dams in the country is also good solution to solve the problem of water shortage. Million of acre feet of valuable water which was flowing into the sea every year could be stored for irrigation at a time when it was needed the most. We should build the Kalabagh dam for the betterment of the country from acute water shortage in future. However, officials of each province should be consulted for the construction as well as for equal share and distribution of water. It is also suggested that if any province was prepared some water out of his own share to other provinces it should be accepted as a gesture of good will and not as a matter of right . The Kalabagh dam project should be supplemented with supportive irrigation projects in Balochistan, Sindh, Cholistan and the NWFP to take the benefits of additional water available from the Kalabagh reservoirs to take their respective areas. Experts say that it was the most researched and investigated project of the world approved by the world top irrigation and dam experts on which Rs.1 billion had been spent so far on investigation. Recently, parts of Balochistan, Cholistan and some parts of Sindh had experienced drought and famine like condition a few months back where a number of casualties had been taken place besides the loss of 40% of cattle. The politicians have to use their wisdom rather than emotion to come to a decision in the country's national interest and the people in the issue of building as many as reservoirs as possible in the minimum possible time, making real and actual policy involving the water crisis, collection of rainwater in depression. Water source development needs to be accorded due priority in the rain- fed areas where small or mini dams can be constructed in proximity to the commended area.
The crisis of water shortage for irrigation can only be over come and proper individual farmer for water management practices. Some of the points to be kept in mind are as: evaluation of available water resources, development and improvement of existing irrigation systems, judicious and efficient use of available irrigation water, control of evaporation from water surface in reservoirs and canals conjunctive use of surface and ground water, evaluation of water requirement of various crops, knowledge of modern techniques of crop and water management, active participation of farmers in water users association, better understanding between government and farmers community. The tail end farmers on a watercourse do not receive their due share. This is due to prevailing technological and socio- political conditions. This unreliability of water supply at the tail ends of canals and watercourses due to the situation and distribuatries and the presence of influential people at the head of canals seriously affects the morale and production of the tail end farmers. Reliability and equity of water distribution is imperative to provide opportunities to all farmers in a canal command area to increase crop production. Massive education in proper use of water along with modern techniques of land leveling can save substantial quantum of water. To obtain the best results, effective co-ordinations between the departments of irrigation and agriculture is the cardinal point for success. Let we Pakistani pray to Almighty Allah in a true sense for the betterment of Agriculture and for the rainfall to submerge our valuable dried lands for the cause of human remedy.
