Diversion of atmospheric water

Water is life, so goes the adage

Available water on earth approximates 1400 million cubic kilometers of which only 2.5 percent is freshwater that can be used by plants, animals and humans. And again 90 percent of this amount of fresh water is not readily available i.e. the balance 0.25 percent of the water on this world that remains for use by humans and other organisms is only about 93,000 cubic kilometers. The groundwater comprises 31 percent of the total freshwater compared to 0.3 percent for rivers and lakes. Annually 110,000 billion cubic meters of rainwater falls on earth, of which 70,000 billion cubic meters evaporate before they can be used. This means that just 40,000 billion cubic meters remain; however, a great deal of what remains is inaccessible, which permits just 12,500 billion cubic meters for use.

Water is the source of life and in all of its forms is the engine for the economic growth and as such, its use has been continuing to be dynamic. While the world population increased three-fold during the twentieth century, water withdrawals increased six-fold. Current withdrawals at the global level account for about 10 percent of world's total renewable water resources and of this withdrawal half is consumed. The withdrawal of water is greatly linked with the size of population. The global population of 6.21 billion has been projected to reach 8 billion by 2025. Increase in world population means increased water use and less availability on a per capita basis.

Population growth is of most concern where countries are least able to deal with its consequences. Key issues in providing for increased population will include the achievement of adequate income levels, food security, employment, and the provision of basic social services. Also critical is the sound management of natural resources, water in particular, that in many developing countries, still directly support the livelihoods of a majority population. In 1989 there was some 9,000 cubic meters of freshwater per capita available for human use. By 2000 this had dropped to 7,800 cubic meters and is expected to further plummet to 5,100 cubic meters per capita by 2025. If water consumption per capita at the global scale reaches the current level in developed countries, over 90 percent of the available water resources would be utilised by 2025. The global consumption of water is doubling every year, and it is estimated that in 2025, if present rates of water consumption are maintained, five billion out of the world's eight billion people will be living in areas where it will be difficult or even impossible to meet the basic requirements.

World Resources, a publication of the United Nations Environment Programme, the World Bank and the World Resources Institute, has a dire warning that the world's thirst for water is likely to become one of the most pressing resource issues of the 21st century. In some cases, water diversions are so high, relative to supply, that surface water supplies are literally shrinking and groundwater reserves are being depleted faster than they can be recharged by precipitation. The hydrological relationship between groundwater, surface water and atmospheric water is a complex composite phenomenon in which one cannot be isolated from the other because of its interdependencies. The world's renowned hydrologists have also found that destroying water's natural habitat not only creates a supply crisis for people and animals, it also dramatically diminishes the amount of available freshwater on this planet. This is the point of alarm.

Worldwide, agriculture accounts for more than 70 percent of freshwater consumption, mainly for irrigation of agricultural crops. Agricultural demand for water is projected to increase sharply, since much of the additional food that will be needed to feed the world population in the future is expected to come from an increase in irrigated land.

Groundwater meets the need of about one-third of the world's population, and is the only source of water for rural dwellers in many parts of the world. Falling water tables have also exacerbated land subsidence in many regions. In Gujarat, India, for example, excessive groundwater withdrawal has caused the water level in aquifers to fall, by 40 metres in some cases. Over-abstraction has also affected the quality of groundwater. This has led to seawater intrusion along shorelines, causing salinisation of coastal agricultural lands. In Madras, India, salt water intrusion has moved 10 km inland, rendering many irrigation wells useless. The increasing human population heavily spurs groundwater usage. The over exploitation of the planet's major river systems is also threatening the finite source of water. The number of large dams world wide has risen from just over 500 in 1950 to 38,000 to-day and the number of watercourse altered for navigation has grown from fewer than 9000 in 1900 to almost 500,000 now.

The Nile in Egypt, the Yellow River in China, the Colorado in America and the Ganges in South Asia are among the major rivers that are so dammed and diverted, that little or no freshwater reaches its final destination for significant stretches of time. The only other source remains un-diverted is atmospheric water.

The Government of Bangladesh adopted the National Water Policy designed to ensure continued programmes towards fulfilling national goals of economic development, poverty alleviation, food security, public health and safety, decent standard of living for the people and protection of the natural environment. Every public agency, every community, village and each individual has an important role to play in ensuring that the water and associated natural resources of Bangladesh are used judiciously so that the future generations can be assured of at least the same, if not better, availability and quality of those resources. The national water ambience has not been able as yet to generate waves of concerns at the fringe of the population, as the transboundary terrorism and corruption, because unlike those water still hits people very selectively seasonally. Rather it has been imploded by thin understanding about water issues within gauging river waters and dumping money into them for their management.

With a present population of around 130 million, Bangladesh is amongst the most densely populated countries in the world. The national population is expected to increase by more than 40 per cent totaling 181 million in 2025. The total useable static surface water resources estimate is 11,784 million cubic meters. This country being very close to the world's wettest place, Cherrapunji, where the average annual rainfall is 10,800 mm, receives 2300 mm on an average per year. The groundwater resources estimate is not in full agreement by the national water experts. Each day, on the average, approximately 3000 million cubic meters are discharged into the Bay of Bengal, although dry season flows are much lower.

Irrigated agriculture in Bangladesh claims 59 percent of its water use, compared to 10 percent for industry, 13 percent for households and municipalities, 15 percent for navigation and 2 percent for environment. The irrigation coverage by groundwater is 69 percent and by surface water, 31 percent. In the capital city, the water table of the groundwater aquifer has been alarmingly depleting. During the last decade the water table has dropped by about 25 meters. Arsenic contamination of the groundwater has already set back past successes and future developments. The data on advancement of salt water inland due to groundwater abstraction is not knowingly available. Reportedly however the salinity front has advanced upto 280 km. upstream from the coast on the south-west due to diversion of surface water in the Ganges by India. India's gigantic river linking plan includes another 30 rivers for diversion at the upstream of Bangladesh.

Conflicts arising out of water diversions, not as understood today, are as old as human habitation on earth; whatever be its scale. Borne out of the desperation of water stress the science of cloud seeding has been in place to provide increased precipitation for crops in meeting the demands in some parts of the world. The seeding is the artificial formation of precipitation in clouds. This feat has been achieved by sprinkling water-absorbing powder over the cloud which triggers imagination that the days of diverting atmospheric water on this world will not be far. Lest this really happens the question arises as to what should be the basis for sharing atmospheric water -- population, land area or ocean surface of a country? In this backdrop, is it even remotely possible that this lush blue and green planet could one day be like Mars, where oceans consist of dust and rock in place of deep waters swarming with diverse and magnificent forms of animal and plant life? Humankind must not let it happen through their folly.

Md. Saeedur Rahman is Chief Engineer, CERP, BWDB, Dhaka.