Water is the most valuable resource on the earth an integral part of the environment. Its availability is indispensable to the efficient functioning of the biosphere. The settlement of most of the great ancient civilizations has been generally associated with a reliable and clean supply of water with convenient sources. For example, the Egyptians centered their civilization on the Nile. Mesopotamia (the land between the Tigris and the Euphrates rivers) was the home of several important ancient empires. Chinese civilization was located principally in the Yellow and Yangzi river basins. Since the dawn of Indian civilization, the Ramayana, Mahabharata, the Arthashastra by Chanakya (3rd century BC), Puranas, the Vrahat Samhita (550 A.D), the Meghalaya (900 AD), Panini's Astadhyayi and various other Vedic, Buddhist, and Jain texts contain several references to the various processes of the hydrological cycle and traditional water harvesting structures and water being revered as a life-giving and sustaining force. The bible quotes, I am the Alpha and the Omega, the beginning and the end. To the thirsty, I will give water without a price - Revelation 21:6. In Islam, the Sharia law in Koran translates to laws of sharing water. Water facilitated relatively rapid transportation before about 1850 C.E. From the late 15th through the 18th centuries, Europeans explored all the major oceans.
Besides earth, there are shreds of evidence of water in a variety of places in the Universe including the Moon, Mars, Jupiter's moons, comets, and interstellar clouds. Yet, until today, it is not clear why there is more water on the Earth than on the other planets of the solar system. Except for fossil water, all water on the planet Earth circulates throughout the atmosphere, geosphere, and hydrosphere. Amazingly, less than 1% of the earth's water is available for human consumption. Almost one-quarter of the world population lacks a safe supply of water and half the population lacks adequate sanitation. Over 90% of the world's developing countries, located in arid and semi-arid areas, are under higher water stress. Over 50% of the world's population is estimated to be residing in urban areas, and almost 50% of the mega-cities having populations over 10 million are heavily dependent on groundwater, and all are in the developing world. Nearly 40% of global food production is attributed to irrigated abstraction, and 70% of the world's groundwater withdrawals are used for irrigation purposes.
A safe and stable water supply is of vital importance to all socio-economic sector's development. Water has always been an important source of power and remained an essential component in all kinds of manufacturing processes and one of the most important components of sustainable development. It is essential for natural habitat - for drinking, cleaning, agriculture, transportation, industry, recreation, animal husbandry, and providing electricity for domestic, industrial, and commercial use. On the other hand, extreme events of more or less water may impact not only human society but also the aquatic and terrestrial environments. Expanding human activities have greatly impacted the water cycle, resulting in a growing number of global water problems and life-threatening hazards. Misuses of water resources and poor water management practices have often resulted in depleted supplies. Most people take water for granted. For many, water becomes an important factor until one turns on a faucet or flushes a toilet and doesn't find water flow. Conflicts over water have become more common among competing water users.
In recent times, due to the increase in population, urbanization, industrialization, and use of chemicals in agriculture, there is an ever-increasing threat to the quality of the water resource base, resulting in a decrease in freshwater availability. While this crisis is most pronounced in the developing countries, the developed world and economies in transition also experience major environmental problems and human health consequences. The problems also include water shortages due to imbalances between water demand and supply, and ecosystem deterioration, caused by improper land use. Erosion and sedimentation, floods induced by urbanization, the problem of fresh and saltwater interaction both in the surface water and in the groundwater environment. While normally associated with less dramatic hydrological phenomena than the arid zones, the humid tropics and temperate zones remain the focus of interest. Apart from these, water resources management problems exist in the fragile ecosystem of drylands, wetlands, mountains, coastal zones, and small islands, irrespective of their geographic/climatic location and land use such as urban, peri-urban, and rural areas.
While the urban clusters look for low to moderate volumes of high-quality water, rural clusters look for a large quantity of high-quality water, in inefficient field distribution and drainage systems. In many areas of India, due rise in water demand for irrigation and other purposes, inadequate availability of surface water supply, groundwater will continue to be used intensively. Farmers adopt groundwater irrigation due to the apparent reliability of storage offered by mechanized drilling and pumping, and the flexibility of groundwater exploitation, but remain indifferent about quality unless the groundwater is saline. Increasing indiscriminate groundwater use has crossed the sustainable limits. In different parts, environmental problems are evident, such as; lowering in groundwater levels, a decline in productivity of wells, more seepage from canals, increasing trend of salinity and groundwater pollution, intermixing of contaminated water with freshwater, etc. The problem is also compounded by the complexities of the interactions among the physical, hydrological, meteorological, and biological environment, management of the natural and the socio-economic systems.
Increasing water use and pollution generation have crossed the sustainable limits in many parts. The story of each region or city may be different, but the main reasons for the water crisis are common, such as increasing demand, the zonal disparity in the distribution of water supply, lack of ethical framework, inadequate knowledge and resources. Thus, the issue of water management is multidimensional, related to a reliable assessment of available water, its supply and scope for augmentation, distribution, reuse/recycling, its existing depletion, degradation, pollution, and its protection from depletion and degradation. However, like surface water resource management, not much-concerted effort has been made for the management of the hidden underground water resources. Water supply schemes, generating large amounts of wastewater, are normally designed and built, without the required matching drainage networks and wastewater treatment facilities. So far, water has been managed in a fragmented way. This fragmentation of approach also impedes coherent hydrological analyses at regional, continental and global scales. The incorporation of the social dimension underlines the need for improved, more efficient management of water resources and the more accurate knowledge of the hydrological cycle for better water resources assessment.
Since the latter half of the 20th century, rapid population growth and expanding human activities have given rise to a variety of serious water problems at the global, regional, and local levels. The expression, "the 21st century will be an age of water", embodies both the concern that water issues may cause international conflicts and the hope that these same issues will promote international cooperation. The growing concern for the water sector has been echoed repeatedly at several international forums beginning with the UN conference on the Human Environment, Stockholm in 1972 to the 3rd World Water Forum, Kyoto in 2003. United Nations declared the year 2003 as the International Year of Fresh Water. The UN General Assembly at its 58th session in December 2003 agreed to proclaim the years 2005 to 2015 as the International Decade for Action, "Water for Life", and beginning with World Water Day - March 22, 2005. To solve the aforesaid water problems, science-based research efforts must be promoted to clarify the structural relationship between the water cycle and human activities, as well as establish a sound and sustainable relationship between them.
The increasing worldwide pressure on water resources under anthropogenic and environmental change requires an integrated multidisciplinary approach to address issues involving water resources assessment and management; taking a holistic view of the water resources, considering issues, such as the quantity and quality of surface water and groundwater, and their interdependence, freshwater and saltwater interface, urban growth, and changing land-use patterns, as well as risks and hazards of flood and drought; identifying the pertinent parameters, phenomena, processes, and possible changes of the hydrological cycle, and evaluating the water requirement of different development alternatives; simultaneously addressing science and policy, based on reliable physical and socio-economic information. Enhancement in water availability and safe water supply will be guided by the policies, plans, and technologies at our disposal, in addition to political, socio-economical, biological, and other factors. Choices based on the best obtainable detailed scientific information, guided by ethical considerations, offer the best hope to protect water from depletion and pollution.
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