With the continuous increase in population and further improvement in the quality of life for more and more people, the demand for water is bound to increase manifold in years to come, says G.L. Asawa, former Professor and Head of Civil Engineering, IIT Roorkee, and Professor and Dean (Administration), GLA University, Uttar Pradesh.
Water plays an important role in deciding the climatic pattern of a region. Water sustains all kinds of life on planet earth. While water is beneficent in several ways, it has also caused havoc in the form of floods since the beginning of civilisation. Prosperity, health and material well-being of any country is very much linked to its ability to store water and make it available suitably for use by its people.
Requirement of water
Human beings need water for their various day-to-day activities such as domestic, municipal, irrigation, hydropower generation, industrial, navigation, maintaining wildlife habitat, maintenance of ecosystem, and recreation etc.
Three basic requirements of food/agricultural production are soil, seed, and water besides sunshine, fertilisers, insecticides etc. Agricultural use of water alone was nearly 90 per cent of all water use in 1900 and is presently around 60 per cent (the world average; in many countries, however, it is still around 80 per cent). This declining trend is expected to continue in view of the technological advances that would take place in the field of agricultural science. However, due to the ever-increasing population and increased consumption pattern, the demand for food grains and, hence, water for agricultural needs, is likely to further increase by around 40 per cent in the next 20 years.
Hydropower plants do not cause any environmental pollution. They do not consume water and operate at an efficiency of around 80 to 90 per cent and can be started or shut down quickly which makes them ideally suited for peaking plants. Reservoirs created for electricity generation can also be used for meeting other water requirements such as those of water supply, irrigation, navigation, and recreation etc.
Water is an important requirement for electricity generation from fossil and nuclear fuels too as it is used for generating steam or for cooling and other purposes. The paper industry’s water requirements (40 to 400 cubic metre per tonnes of paper) may vary depending on the type of raw material. Water is also used in coal mining, coal slurry pipelines, crude oil refineries and many other industries. Water is also needed in a river to dilute industrial wastes that are discharged into river systems. The bulk transport of goods by waterways is not only fuel efficient but is also much less air polluting.
With the continuous increase in population (expected to be stabilised only after 2060) and further improvement in the quality of life for more and more people, the demand for water is bound to increase manifold.
Availability of water
Of the total water (about 1.4×109 km3 in volume) on the planet earth, 96.5 per cent is in oceans. Approximately, 1 per cent of the remaining 3.5 per cent is contained in deep aquifers or in saline lakes. Thus, only 2.5 per cent of the earth’s water is fresh water of which around 68.6 per cent is in frozen state (glaciers or polar ice) and 30.1 per cent is contained in shallow aquifers. This means that only 1.3 per cent of the earth’s fresh water is in mobile state on the surface of the earth and is contained in the surface and atmospheric phases of the hydrologic cycle.
Another important feature about the availability of water is its uneven spatial and temporal distribution which is primarily responsible for the draughts and floods in almost all countries of the world. For example, India supports around 17 per cent of the world’s population over only 2.4 per cent of the world’s land surface and 3.5 per cent of the world’s fresh water resources. Per capita water availability of run-off in India is only around 2,000 cubic metres per year as against 17,500 cubic metres per year in erstwhile USSR, 6,500 cubic metres per year in Japan and 6,200 cubic metres per year in USA.
Due to the rapid growth of the population, per capita water availability will further decrease in countries like India. Unprecedented pressures on account of poverty, illiteracy, population, erratic distribution of rainfall resulting into frequent floods and draughts etc. on the environment of any developing country make its relationship with nature very fragile. The nature’s ability to cause havoc can be appreciated by the Kosi flood of 2008 when the river Kosi (in India) changed its course and displaced millions of people. This can be checked by having a storage reservoir upstream. Such developing countries have highly complex ecosystems that, once destroyed, are very difficult to restore.
Therefore, most of the countries, especially the developing ones, need to have massive water resource projects either for flood control or for meeting water demands (for domestic, municipal, irrigation, and industrial) or for power generation on a sustainable basis. The developed ones, having negligible growth of population, have already harnessed their water resources to a very large extent to meet all their requirements comfortably.
During the last two decades, the water sector has witnessed some rapid developments. Due to continued increase in scarcity of water in many parts of the world, the need for integrated and sustainable development and management of available water resources has received considerable attention.
Because of excessive withdrawals and reduction in natural recharge, however, the power requirement for the purpose increases. Different regions of the world have their local traditional practices (like step well in India) in this regard. Since irrigation takes away a large percentage of water being used by human beings, considerable emphasis is being placed on the innovations in biotechnology to reduce irrigation requirement and yet enhance the yield of agricultural productions both qualitatively as well as quantitatively. In addition, measures such as reuse of industrial effluent, inter-basin transfer etc. may be of immense use to mitigate water scarcity.
Storage and diversion works
Just as availability of surface water is variable spatially as well as temporally so is the demand of water. The mismatch between demand and supply needs to be rectified for the sustenance of human lives. Run-of-the river schemes would not be adequate when the variation in discharge is large as in the case of non-perennial rivers. Small check dams too would prove inadequate for the kind of prevailing spatial and temporal variation. If one were to create given amount of storage by means of only small dams, more area would be submerged compared to the situation when only one large dam were to be constructed for the same storage. Therefore, surface water needs to be harnessed. Storage and diversion type water resource projects have been adopted globally since very long time. Any major water resource project is usually designed to serve more than one purpose so as to derive maximum benefits out of the investments made. They are, therefore, invariably multi-purpose projects that are useful in more than one way.
Rainwater harvesting has obvious advantages and is, therefore, being resorted to either by choice or by legislation in water-stressed regions. Large scale rainwater harvesting, however, may have possible adverse impacts on different aspects related to the region’s hydrological cycle, environment, climate, water quality, geotechnical, seismic, and infrastructure including buildings, bridges, road and rail networks etc.
Because of rainwater harvesting, the runoff in a river downstream would decrease. This may convert some rivers dry in the beginning. The effect of large-scale rain water harvesting may extend up to the sea as lesser surface water would find its way to the sea.
Rainwater harvesting projects should take into account all these issues so that there is minimum adverse impact of any kind. Further, the project must be dynamic in the sense that with changes in hydrologic pattern of the region, rain water harvesting be also modified from time to time.
Reuse of industrial effluent and wastewater
It would, obviously, be advantageous to recycle repeatedly the used water be it either the municipal or domestic discharges of used water or industrial effluent.
Domestic wastewater from kitchen and bath rooms may be passed through a sand filter and treated with alum to make it useable for toilets. Likewise, wastewater from toilets may be treated in bio-digesters (capable of treating biodegradable domestic wastes too) to yield biologically safe slurry that can be used to cultivate vegetables and recharging the ground water as well. Generation of biogas would be an added advantage.
Statutory provisions invariably require industrial effluents to be well-treated before being discharged into rivers or lakes or any water body. Well-treated wastewater can be used for some select irrigation activities, industrial uses, recreational uses, recharging of aquifers, non-potable uses etc.
Innovations in biotechnology
There is considerable scope for improvement in agricultural practices so as to improve yield per unit of land as well as yield per unit of irrigation water. In majority of the developing countries the yield is less than 2 tonnes per hectare against about 10 tonnes per hectare in the developed countries. With innovations, the demand for irrigation water can be considerably reduced.
In view of the prevailing spatial mismatch between demand and supply of water, another alternative appears to be inter-basin transfer by interlinking major rivers of the world or a country so as to transfer water from a surplus basin to a deficit basin. This kind of transfer of surplus water through interlinking of major rivers would involve several challenging technical and non-technical issues including the main issue of the people of the surplus basin agreeing to the transfer of their waters to the deficit basin.
Any developmental project, constructed for the well-being of human beings, has definite impact on the surrounding ecosystems (involving organisms i.e. plants, animal, and human beings and their environment) and environment that includes the earth resources of land, water, air, vegetation, and manmade structures.
The objections to the construction of large dams for any major surface water resource project are mainly on account of human displacement, ecological imbalances and other issues such as waterlogging, deforestation, reservoir sedimentation, impact on climate etc. Undoubtedly, rehabilitation involves emotional, psychological, and cultural issues rather than purely material compensation in the form of land and monetary compensations. In this regard, NGO’s, supported by dedicated and adequate funding, can play an important role in safeguarding the interests of the displaced population.
The area of farmlands submerged on account of any water resource project is a negligible fraction of the area irrigated by the project. Hydropower continues to be cheaper and environment-friendly compared with thermal or nuclear power.
The decision of water resource development should be based upon analysing the future scenario “with” and “without” the proposed development. The alternative of not building a required water resource project would certainly deprive the concerned population of irrigation water, hydropower, employment, and added income so essential for their welfare. Both developmental activities and an intact environment are equally important for sustained well-being of human beings. Therefore, the water resource projects must be developed, whenever and wherever needed, and managed such that they minimise adverse environmental impacts and maintain ecological balance while meeting the demands of human beings. The developmental and environmental issues should be reconciled by adopting an integrated and multidisciplinary approach not only for the planning but also for the implementation of the projects. Such an approach would include issues such as treatment and management of catchment, rehabilitation, forestation, drainage measures etc.
The complexity of environmental processes seldom permits accurate prediction of the full spectrum of changes in the environment brought about by any particular human activity. Because of the size of any major water resource project, assessment of its environmental impact becomes still more difficult.
Further, it is imperative that the water potential created by the existing water resource projects be fully utilised for which purpose all necessary steps are suitably taken. An improved watershed-based water resource/canal irrigation management would certainly minimise wasteful use of irrigation water besides improving productivity with equity and stability.
Last but not the least, controlling the population growth is imperative to prevent further worsening of the water scarcity.