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"....A transparent, colourless, tasteless and odourless liquid, which is chemically a combination of hydrogen and oxygen, falling as rain etc., forming seas, rivers and so on...." is the technical explanation for water, the vital element of life and a truthful companion of humanity in his progress. No doubt, water is an irreplaceable natural resource, without which man can neither live nor be active. The rich cultural heritage of our nation, reflected in the epics, reminds the acceptance of the vital role of water, even in the vedic period. We are fortunate to inherit a generation which taught us that water is one of the five integral elements of human body. In the theory of 'Pancheekarna', it is very elaborately pointed out how these Five Elements are evolved, how they intermingle and how, from the subtle tanmatras the gross elements come out. While taking care of water and treating it as a natural resource has allowed civilizations to grow and flourish, the mismanagement of this vital resource has caused the fall of more than one civilization. The availability of water has played a decisive role in the civilizations as far back as the days of Mesopotamia and the Pharaohs of Egypt. More than 5000 years ago, people began building channels to carry water to dry fields. In India too, the early civilization as well as the settlements, originated and developed mainly in the river valleys and a number of Indian cities located on the banks of the rivers stand as towering examples of the fact that water is the essential input that promotes or restricts growth. Perhaps, no one has described the role of water better than the well-known Russian scientist, V.I. Vernadskiy, who said: "Water occupies a unique position in the history of our Planet. No other natural substance can be compared with it in so far as its influence on the course of the most grandiose basic geological process is concerned. All substances on this Earth -whether mineral, rock or living body -contain some water: All matter on the Earth is affected by water in some way and is either impregnated with it or surrounded by it". |
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Water as a resource: The multiple dimensions The Planet Earth is called the "Blue Planet" as two-thirds of it is covered with water. While the hydrologic cycle ensured that the sumtotal of water in different forms is same as that was, since the beginning, the unprecedented increase in demand for this vital resource has made it a resource in crisis. Today, the UN figures indicate that at least 1.7 billion people do not have an adequate supply of drinking water. At least 30,000 people die everyday especially in the poorer parts of the world, because of lack of water or its unsanitary nature. This means that about 10 million needless deaths occur every year. In March 1990, the United States Centre for Disease Control reported that 26,000 cases of illness, known to have been caused by contaminated drinking water, occurred between 1986 and 1988. Thousands more were suggested; but could not be proved. The World Health Organisation (WHO) estimates that 80 percent of all illness are related to water. Added to these are the difficulties arising out of the paradoxical situation of "abundance and scarcity" due to spatial and temporal variability of rainfall. It is interesting to note that the world's rainiest spot, Mount Waialeale in Hawai, receives 1168 cm of annual rainfall on an average. On the other hand, 15 miles away is a region that averages less than 50 cms of rainfall, a year. India is a monsoonic region with the exception of Kashmir in the north and some portion of the southern peninsular region. The average annual rainfall varies from a high of 1149 cms at Cherrapunji in Assam to a low of 21.7 cm at Jaisalmer in Western Rajasthan. Around 75% to 90% of the rainfall occurs over the country during 25 to 60 rainy days of the four monsoon months from June to September. There is also a large variability from year to year, the co-efficient of variation of annual rainfall being above 20% in most parts of the country. These spatial and temporal variations brings home the urgent necessity for scientific water management. The anomalies and variations apart, India is a country blessed with a bounty of water resources. Every year, the country gets a total precipitation of 400 Mha-m on an average, of which 114 Mha-m is the utilisable water and 188 Mha-m, is the amount flowing into the rivers. The occurrence of maximum precipitation over a short period of time and the high evaporative demand, (Fig-1 )
alongwith the lack of appropriate conservation and management measures, has converted most of the country into a paradoxical situation, where the scarcity of water is severe, even after having a very high precipitation. While the total precipitation remained more or less same, the size of the dependent population has increased manifold, over the years. This has resulted in the large scale reduction of per capita water availability. For example, the per capita availability of 5236 cu.m of water in 1951 has decreased to 2227 cu.m in 1991, when the population increased from 359 million to 844 million (Fig.2). The situation has been further deteriorated in those river basins where the density of population is high due to a number of reasons. In order to meet the increasing demands of the growing population, particularly to meet the resultant food requirements, considerable investments have been made to provide maximum irrigation facilities (Fig.3). A number of major, medium and minor irrigation projects, spread across the country provides irrigation facilities to a wide cross-section of the farmers. However, the fact that we have not been able to optimally utilise the established potential (Fig-4), remains as a serious limitation and a matter of immediate attention. Looking towards the future The availability and management of the water resources is inextricably linked to the dependent population. The population
The carrying capacity The carrying capacity of a nation could be broadly identified as the maximum pressure of population which could be sustained by the available resources, without damaging the environmental fragility and allowing necessary replenishment to meet the require- ments of the subsequent generations. The Food & Agricultural Organisation (FAO) had conducted a comprehensive evaluation of national carrying capacities of different countries, with particular reference to food needs. In case of India, the study concluded that in 2000 AD, assuming low levels of inputs such as low-yielding varieties, long fallow periods, poor conservation measures and so on, the country will be able to support only 1038 million people. At an intermediate level of inputs, the population supporting capacity will be 1800 million, whereas it can go up to 2621 million, provided highlevel inputs are used in the system. Water Demand The expected demand on the available water resources from different sectors of the user community need to be assessed to arrive at an effective plan of action towards sustainable management of the water resources. Though the estimation of the actual demand is a complex task, a number of studies have been carried out to assess the future demand. Domestic Demand While the World Health Organisation (WHO) has recommended an urban supply of 200 litres percapita daily (lpcd), the supply in urban India varies from 70 to 250 lpcd, thus giving an average value of 140 lpcd. But at present, it is estimated that only 85 percent of the urbanities and 79 per cent of the rural population has access to safe drinking water. The National Drinking Water Technology Mission had set a target of atleast one source within a radius of 1.6 km radius, providing 40 lpcd in the rural areas, besides 30 lpcd in desert areas for cattle. Industrial Demand The domestic need of the nation apart, necessary provision has to be made to meet the industrial requirements. While it is difficult to foresee the industrial progress of the nation in the coming years and thus estimate the water demand, various studies put the industrial need as almost 1.6 to 2 times the domestic need. The second Irrigation Commission had estimated the domestic and industrial demand of the country as 3 Mha-m and 5 Mha-m, respectively. Demand from power sector Yet another sector which needs to be taken into account for estimating the total demand is the power sector. There are a number of large and medium hydro-electric projects that are being planned in the coming years, in addition to the existing ones. While the number of large hydro-electric projects coming up in the country in the future may be less, a number of medium and minor projects are expected, particularly after the opening up of the economy and allowing private investment in this area. Irrigation Demand The domestic, industrial and energy requirements apart, irrigation is the major sector, for which maximum allocation need to be made. The irrigated area in the country was only about 22.6 mha in 1950-51. As compared to this, the irrigation potential created upto the end of Seventh Five Year Plan is 79.74 mha, of which the surface and groundwater contributions are 43.9 mha and 35.84 mha respectively. In order to meet the ever increasing food demand of the growing population, the area under irrigation has to be enhanced considerably. Using different models, the water demand in the coming years for different user segments has been worked out by various investigators (Table-1 ).
While the associated complexities and the lack of necessary information do not allow an accurate estimate, the above figures provide a broad indication of the nation's demand in the coming years. Meeting the foodgrain requirement The ultimate food production potential of the country under the present production patterns of area, productivities, water use efficiency etc is estimated to be around 258 million tons, of which 210 million tons come from irrigated agriculture and the remaining from rainfed regions. However, we may require a minimum of 353 million tons to feed a population of 1700 million, at the present annual precapita consumption rate of 208 kg. On the other hand, if we take a reasonable calorie intake and hence a percapita food grain consumption of 280 kg, we may require a foodgrain production level of 476 million ton. While scientific agricultural practices, including the application of appropriate fertilizers and use of high yielding varieties, can increase the productivity, the yield can be enhanced to a reasonably better level only through appropriate irrigation. The irrigation water demand for low, moderate and high yield levels has been worked out and the same is given in Table-2
As evident from Table-2, the irrigation water demand exceeds the net irrigation water available. In other words, the limiting factor for achieving desired food grain production from a minimum of 353 million tons to a maximum of 476 million tons is not the land, but water. Ultimate Utilisable Potential Having examined the expected future demand from various sectors, it would be appropriate to look at the Utilisable water resource potential of the country. Though the nation is blessed with an average annual precipitation of around 400 mha-m, the utilisable amount is considerably less than the gross amount (Table-3).
While these estimates are of empirical nature, these pro- vide a valuable insight about the broad availability. A careful analysis of this information in the backdrop of the projected demands by various sectors brings out the challenges in the water resource area, facing the managers and the users as well. This calls for a careful analysis of the various options infront of us and points to the inevitable need to use all possible resources, particularly the immense potential of new technologies, as that of space technology, to ensure sustainable development and management of our water resources. A Space Agenda Space has always been a fascination to mankind. That apart, it has provided humanity, the vantage point too, to view the earth in its totality. Over the last three decades, the unique capability of space-based sensors to provide timely and accurate information over a wide range of the electromagnetic spectrum, on the type, state, extent and condition of the natural resources, has been successfully harnessed, towards national development. Today, the remarkable achievements of the Indian remote sensing community in reaching the benefits of this technology at grass-root level, is globally acclaimed and has led to the recognition of this technology as a powerful and invaluable aid in our efforts towards sustainable development. Water resources development and management has been an important area where space-based remote sensing techniques could bring in remarkable achievements. While acknowledging the accomplishments, we need to identify the specific agenda of action and ensure the optimal utilisation of this technology towards realisation of the goals. Understanding the hydrologic cycle Scientific understanding of the intricacies and interlinkages, associated with various hydrologic processes is an important element, not only to manage the water resources of the earth, but also to understand its environment and the climate, as hydrological cycle is a major medium for the biogeochemical cycle. Though the space potential is established, we are yet to achieve the necessary breakage through in dealing with the water cycle, particularly towards analysing its role and behaviour in the land-ocean-atmosphere continuum Associated with the terrestrial water cycle, there is a continuous, exchange of energy, water and other substances throughout the atmosphere, the landscape and inland aquatic systems. Vegetation cover is influenced by the climate. Conversely, vegetation plays an important role in determining the partitioning of the energy and water inputs at the lower boundary of the land-atmosphere system thus influencing the surface hydrological process and consequently the climate. A thorough understanding of key biological -hydrological interactions of the soil-vegetation-atmosphere system is a prerequisite to predicting impacts of climate change on unmanaged and managed vegetation. Evaluating the impact of climate change Demographic development, economies in transition, the growing consumption of energy and natural resources and its consequences for the future of our environment have become major challenges. The climatic changes are expected to have a profound impact on the water cycle opening up new challenges and inexperienced scenarios. In otherwords, the very same process associated with the occurrence of water may change leading to alterations in spatial and temporal distributions as well as in human responses to weather. To cite an example, when daily summer mortality in New York city and Shanghai, China were compared to maximum temperature, a sharp increase is noted beyond a temperature threshold (Fig.5). The magnitude of this problem assumes great significance when we consider the suspected increase in temperature as a result of global warming (Fig.6). It is now widely accepted that the increased anthropogenic activities are leading to greenhouse gases, resulting in global warming. Preliminary studies indicate that a 1°C rise in temperature and 10% reduction in precipitation can pave the way for 40-70% reduction in runoff. Thus, evaluating the impact of climate change on the availability and distribution of water need to be a matter of extreme importance.
Water Resource Accounting Accounting of natural resource use does not normally take place in the process of economic activities as the costs of environmental degradation and resource depletion are not borne by the economic sectors who cause them. A number of studies have indicated the wastage of water in various consumptive uses (Table-3).
A comparison of industrial GDP per unit industrial water withdrawal is given in Fig. 7. The magnitude of resource loss can be easily understood from the fact that a dripping faucet that leaks just one drop of water every second will waste 15 litres of water in a day or 5320 litres over a year.
Water resource accounting as part of overall natural resource accounting keeps one reminded of the environmental consequences of economic activity. Such a strategy can alter our perception of what kind of development is desirable and in turn, influence the policy decisions. Satellite remote sensing along with appropriate collateral data enable the inventory of quantity, quality as well as the values of the resources. The repetitive nature of space-based earth observation provides the unique opportunity to do the accounting on a periodic basis. A national strategy to water resource accounting on a periodic basis can definitely pave the way for sensitising the community towards effective resource management. Managing the "Abundance as well as Scarcity" Water is a resource, the scarcity as well as abundance of which can cause hardships to humanity. In India, among the major and medium rivers of both himalayan and non-himalayan categories, 18 are flood prone draining an area of about 150 mha and more than 40 mha area of the country is estimated to be flood prone. According to a rough estimate by National Commission of Floods, 75 percent of this area is protectable through appropriate watershed management programmes. While the space capability in near-real time flood mapping and risk zonation based on time series analysis of historic data is widely utilised, the efforts in the coming years need to be on flood warning and flood plain management, using space systems. On the other hand, around 250 districts in the country are drought-prone and 13.2 percent of India's total geographical area has a drought frequency of less than 3 years, as 55 percent of our geographical area is arid or semi-arid. The earth observation satellites have been providing necessary vantage point and repetivity leading to the monitoring and management of drought affected areas. But, it is of paramount importance to realise operational capability to predict the onset of drought in advance by developing suitable models, integrating agrometeorological data with satellite derived information. During the coming years, the Department of Space has planned concerted efforts towards the realisation of a Disaster Management System. The attempt will be to address various aspects of disaster management, including floods and droughts by the synergic use of remote sensing and communication satellite systems as well as ground based capabilities. Conservation as a necessity The conservation of available water resources can be considered as a necessity from which humanity does not have an escape. There are innumerable examples where considerable progress have been achieved by implementing appropriate conservation measures. The overwhelming success of the Integrated Mission for Sustainable Development leading to the implementation of sustainable land and water resource development strategies, arrived at through the integration of remote sensing derived inputs with other collateral data, stands out as unique example of reaching the benefits of this technology at the grass-root-level. A typical example of the improvement in the scenario after constructing a farm pond as part of the IMSD action plan in Uma-Gani Watershed of Chandrapur District in Maharashtra is as follows:
Towards improved irrigation management Management of the catchment, reservoir and the command area as an integrated system, employing the unique capabilities of remote sensing is a major agenda in the coming years. Efficient management of our irrigation systems can only be achieved by periodic assessment of the reservoir systems which receive the inflow of water as well as sediment from the catchment and supplies water down stream. It is feared that nearly 20 percent of the live storage capacity of our major and medium dams would be silted up by the end of the century, which would mean a loss of irrigation potential of about 4 mha. To cite an example, the storage capacity of Nizam Sagar Dam has been reduced by 63 percent in 44 years. The excellent opportunity being provided by satellite remote sensing for capacity evaluation of reservoirs, need to be effectively utilised towards optimal reservoir water management. One of the major drawbacks of the water utilisation pattern in the country has been the poor water use efficiency (Fig.8).
Diagnostic analysis and performance evaluation of command areas towards modernisation and rehabilitation of existing projects has been a major contribution of satellite remote sensing, in this regard. The data availability on a repetitive basis has enabled the concurrent monitoring of command areas for near-real-time information on irrigation extent, crop condition, equity and so on. The requirement of the coming years will be the extension of the present capability towards irrigation scheduling and improved water use efficiency. The realisation of operational capability to determine optimum amount and timing of irrigation needed for a crop, leading to improved crop yield, better water and energy use efficiency, improved soil productivity and so on remains as a major challenge, in the coming years. Inter-river basin water management The spatial and temporal variations in rainfall along with the differences in the topographic and vegetation characteristics has obviously led to river basins with varying water availability. Though the Govt. Of India has identified the interlinking of river basins as one of the solutions to meet the growing demand, we are yet to fully harness the potential in this regard. Under the National perspective plan, a number of link projects have been proposed which includes 21 projects under the Himalayan rivers development component and 17 projects as part of the peninsular rivers development component, for transfer of waters from the water-rich basins to the river basins, where there is a scarcity. The National Water Policy of 1987 too endorsed the need for such transfer of waters. Both components of National Perspective Plan put together would give an additional benefit of irrigation to 25 mha by surface waters and to 10 mha by increased use of groundwater. Quality alongwith Quantity The challenges in realising the required amount to meet the demands apart, ensuring the quality of the available water resources is a major task, particularly with the increased anthropogenic interventions. Over 700 different chemicals have been found in drinking water across North America. Many of these substances have never been tested and no one really knows, how harmful the chemicals are to the humans. Of those that have been tested, 22 have been listed by the National Academy of Sciences as Carcinogens. The Environmental Protection Agency (EPA) estimated in 1986 that some 40 million Americans had potentially dangerous levels of lead in their drinking water from the pipes in their drinking water systems and various natural factors. Having established the immense potential of space remote sensing in identification of polluted as well as polluting sources and thus for water quality mapping and monitoring, the thrust in the coming years need to be on quantification of quality levels. The potential of this technology in implementing comprehensive regulatory policies, still remains under-utilised. Environmental Impact Assessment of various developmental activities on water resources as well as that of water resource projects on the environment, need to be a regular and mandatory arrangement. The obvious conflict between quality and quantity can be resolved to a certain extent through appropriate treatment and recycling mechanisms (Table-5).
Appropriate monitoring and regulatory mechanisms will not only lead to identification of problem areas and realisation of magnitude, but also towards necessary recycling efforts, enabling large savings in quantity. Success through people's participation The key player and the ultimate decision maker in the management of the natural resources, particularly water, is the user at grass-root level. In otherwords, the real success of the management strategies depends on the conviction and acceptability of the end-beneficiary. The peoples participation in the management programmes aimed at sustainable development and utilisation of the water resources, thus becomes a necessity rather than an imperative, which emphasizes the fact that the creation of basic awareness is the key to success. An interesting study by the Indian Council of Medical Research reveals that a change in the present food habits can lead to considerable savings in water and reduce the high dependence on food grains to a certain extent, apart from achieving an improved nutritional value (Table-6).
Based on the above suggestion, the food grains requirement for a stationary population of 1700 million has been worked out as follows:
While it is accepted that a change in the traditional foodhabits may not be possible suddenly, an increased awareness and conviction can definitely bring in a gradual shift towards the improved diet pattern. If our diet shifts from the present average diet to the more nutritious diet, the percapita water saving is estimated to be 400 litres per day. The impact of changing cropping pattern is given in Fig.9. A population need not be fully aware of all the scientific aspects, but a basic awareness is of utmost importance in our eforts towards sustainable development and management of our rsources. Thus, the real success of the programmes depends on the realisation of farmer based information systems which can provide the necessary inputs to the farmer and ensure the reach of high technology at grass-root level.
Fully convinced of the capability of space-based systems and the need for creating awareness at grass-root level through developmental communication, the Department of Space has initiated a major effort in this regard. The on-going Jhabua Developmental Communication Project (JDCP), aimed at providing training and creating awareness among the rural masses on better agricultural pactices, land and water resources management, family planning etc is expected to provide valuable inputs for planning and establishing such networks on a wider scale in the country. Indian Earth Observation Programme: A future perspective While the effective utilisation of remote sensing technology for microlevel developmental planning will be the primary thrust, concerted efforts are planned towards generation of information at cadastral level, enabling easy implementation and monitoring of developmental plans. In tune with the global efforts and in view of the increased need to protect the Planet Earth, environmental monitoring and management will receive adequate attention in the coming years. Besides, it is planned to effectively utilise this technology for strengthening efforts aimed at increasing the agricultural productivity harnessing marine resources, observing meteorological parameters and improving the weather forecast. These apart, ongoing efforts towards upliftment of the rural masses will be strengthened by focussing on continued monitoring, enrichment and management of our land and water resources. A number of satellite missions are planned to enable the monitoring of the environment at various levels, leading to the observation of Planet Earth as a total system for a better understanding of the geosphere-biosphere interactions and for initiating strategies for protection of environment as a part of the global efforts. The IRS-1D which is identical to IRS-1C, the best civilian remote sensing satellite presently orbiting the earth, is scheduled for launch in 1997. The IRS-P4, carrying Ocean Colour Monitor (OCM) and Multifrequency Scanning Microwave Radiometer (MSMR) will provide valuable information for oceanography and marine resources applications as well as for medium range weather forecasting. This will be followed by a CARTOSAT, which will have a PAN camera of 2.5 meter resolution. The RESOURCESAT will offer multispectral data at a resolution of 6 meters, besides data from LISS III* and AWiFS payloads. Thus, the IRS constellation will become the most versatile. remote sensing satellite series in the world, offering a wide range of data and services to meet the varied requirements of the user community, particularly towards better management of our land and water resources. CONCLUSION The "Blue Planet" has provided the humanity, the vital water resource which stood as a faithful companion in our journey towards progress. While the inevitable dependence of humanity on this component of our Planet was accepted since the beginning, we took centuries to realize that it is a scarce resource, which need to be carefully protected and managed for the very survival of the humanoids. Thanks to the technological advances, the present generation is not only blessed with a natural bounty of resources, but also modern scientific tools and capabilities as that of space, to understand and manage the Planet Earth. While the spectacular achievements in the recent decades, in harnessing the potential of space technology towards addressing various aspects of scientific water management, is a matter of extreme satisfaction, the society t large and space scientific community in particular, cannot loose sight of the formidable challenges ahead. A focused agenda and a plan of action along with concerted efforts are required, to effectively utilise the full potential of space technology for sustainable development of our scarce and precious water resource. Albert Einstein said: "Civilization is a race between education and disaster". I hope we will succeed in learning the lessons of the nature and ensuring sustainable utilization of its resources, avoiding a disastrous situation, prompting the coming generations to say that they have inherited a civilized society. Acknowledgement The preparation of the lecture material was possible with the extensive support of Mr. M. Sebastian. Mr. V. S. Hegde, Mr. V. Jayaraman and Dr. M.G. Chandrasekhar also provided their valuable support. I profusely thank them for the same. References
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Sixth Vikram Sarabhai Memorial Lecture
