Water is behind all ecological goods and services from the biosphere that make human life on Earth possible. Water is not only a generator of ecosystem services, like food and energy, it is also a critical agent of change, e.g., functioning as a greenhouse gas and a regulator of temperature on Earth, and a victim of change, e.g., through shocks like droughts and ?oods caused by global warming. Growing populations, expanding economies, mounting environmental pressures, improving living standards, changing consumption patterns, expansion of irrigated agriculture and unsustainable consumption practices are the main driving forces for the rising global demand for water. While the planet’s total population quadrupled over the past 100 years, global water use swelled almost eightfold from 1900 to 2010. These effects are already seen in many major trans-boundary basins – including the Colorado, Ganges, Indus, Lake Chad, Nile, and Tigris-Euphrates – where in each basin yearly water withdrawals nearly equal or exceed long-term flow balances and ecosystem needs, resulting in severe water stress. Groundwater increasingly faces the same pressures as surface supplies. Abstractions have ballooned in recent decades as underground sources have come to provide half of the irrigation water for growing the world’s food supply, and now account for one third of total global water use. Withdrawals are well beyond sustainable levels in many major trans-boundary aquifers with abstraction surpassing natural rates of replenishment, progressively exhausting groundwater reserves. In India, water crisis will also be critical in future. A total of 21 major cities are poised to run out of groundwater next year, according to a 2018 report by government-run think tank NITI Aayog.
The capacity of social-ecological systems to deal with shocks like draught and flood, adapting to changing conditions and transforming in situations of crisis are fundamentally dependent on the functions of water in regulating the Earth’s climate, maintaining biomass production, and supplying water resources for human societies. The massive human interference involving climate forcing, water withdrawal, dam constructions, and land-use change have signi?cantly disturbed these water function. Examples of such transgression are collapse of aquatic systems beyond water quality and quantity thresholds, deserti?cation due to soil and ecosystem degradation, and tropical forest dieback associated with self-amplifying moisture and carbon feedbacks. Large water consumption relative to water availability results in decreased river flows, mostly during the dry period, and declining water of reservoir, lakes, ponds and groundwater aquifer. Most of the rivers are fully or nearly depleted before they reach the end of their course particularly during dry season. Direct victims of the overconsumption of water resources are the users themselves, who increasingly suffer from water shortages during droughts, resulting in reduced harvests and loss of income for farmers, threatening the livelihoods of whole communities. Businesses depending on water in their operations or supply chain also face increasing risks of water shortages. Other effects include biodiversity losses, low flows hampering navigation, land subsidence, and salinization of soils and groundwater resources
At the global level and on an annual basis, enough freshwater is available to meet such demand, but spatial and temporal variations of water demand and availability are large, leading to water scarcity in several parts of the world during specific times of the year. About 71% of the global population (4.3 billion people) lives under conditions of moderate to severe water scarcity at least 1 month of the year. About 66% (4.0 billion people) lives under severe water scarcity, at least 1 month of the year. Of these 4.0 billion people, 1.0 billion live in India and another 0.9 billion live in China. Significant populations facing severe water scarcity during at least part of the year further live in Bangladesh (130 million), the United States (130 million, mostly in western states such as California and southern states such as Texas and Florida), Nigeria (110 million), and Mexico (90 million). The adaptive capacity of people to gradually changing is relatively high, whereas adapting to yearly variations and extremes such as heat wave and heavy rain in particular year poses more difficulties.
Water scarcity will increase signi?cantly over the coming decades and this will bring problems for food security, environmental sustainability, and economic development. The most important driver of water scarcity is GDP growth which greatly overcomes any expected water saving due to technological progress, in most of countries and scenarios. The uncertainty of regional climate change seems to play a secondary role that acts to exacerbate the effects of water scarcity on nations, particularly those that are already experiencing water stress. The water scarcity will be responsible for changes to the atmospheric water content; intensity of extremes, reduced snow cover, widespread melting of ice, changes in soil moisture and droughts. The frequency of heavy precipitation over most areas is predicted to increase with the consequences of rain-generated ?ood potentially overwhelming existing infrastructure leaving little opportunity for water storage. The India must deal with severe and imminent water shortage problems, to which India will not be able to pursue economic growth without over-exploiting nonrenewable resources. The best way to prevent these economic losses is to reduce overall demand by decreasing the amount of water that is wasted, modifying consumption patterns towards less water-intensive products or increasing trade in virtual water. For that purpose, India must give emphasis on cleaning up their production processes and on promoting advanced water-efficient technologies in the energy industry aiming to decrease grey water pollution. Most comprehensive and transparent data monitoring and reporting are essential to facilitate such water stress assessment. Because India mostly suffers from increasing population size paired with low levels of technological development.
The storage of rain water in large reservoir as done in many states leads to loss of water to evaporation and the flow almost comes to end to the river downstream leading to collapse of aquatic ecosystem and to less groundwater recharge. Poor management of reservoir causes man-made flood as happened frequently in Uttarakand, Kerala and many places in India. Management of groundwater aquifers can solve all these problems. Most successful strategies for more sustainable groundwater management are conjunctive use-- substituting surface water use for groundwater use, and managed aquifer recharge, recharging groundwater with surface water. Which are both currently being deployed in the southwestern United States. The Central Ground Water Board, India has estimated that 85 BCM water can be stored in groundwater aquifers from an area of 9.4 lakh square kilometers. The total area of India is 32.7 lakh square kilometers. The total groundwater storage potential would be much larger than the 85 BCM estimated above. Though Centre as well as in states, irrespective of their political affiliations has declared to conserve rain water seriously. This program appears attractive but not yielded expected results as it was observed in maintaining cleanliness of river. The major flaw in water crisis management is that water resources availability assessments are highly uncertain due to inadequate observation networks, and this is expected to get worse into the future. This uncertainty is expected to increase in the future due to climate, environmental, population and other socio-economic development changes. For meeting humanity’s increasing demand for freshwater and protecting ecosystems at the same time, sustainable water resources management in any region depends on many factors that cross several scienti?c, social, economic, political and engineering disciplines. One of the fundamental factors is the quanti?cation of the available resources and the extent to which they can be exploited in a sustainable manner. Another important aspect is that there is uncertainty in all relevant information on water resources. This uncertainty must be appropriately quanti?ed and accounted for during future water management practices. The Proper water scarcity assessment, at the necessary detail, will facilitate governments, companies, and investors to develop adequate response strategies. Water productivities in crop production will need to be increased by increasing yields and reducing nonproductive evaporation.
Water system has become stressed on account of dramatically growing human needs and wastage. As India’s water resource management has been poor, effective management of the limited available water resources becomes critical. Economically, water resources are a common-pool resource. This means that people have no incentive to save or use water efficiently, so effective management to deal with the externality of water use and market failure is needed. In India, over the past decades, water resource management, has been dominated by engineering and the institutional system of water resource management is fragmented and ineffective. Water policies largely fail to account for the economic nature of water resources in relation to their natural characteristics. Water shortages due to poor water quality can be attributed to insufficient investment in environmental protection and weak pollution control. The development of urban sewage treatment facilities, including sewer networks, has been slow to treat the domestic waste water. The major problem is that Government do not have a proper roadmap to tackle the water pollution problem in an efficient and stringent manner based on Water Security Act.
Also there is emergent need to sensitize people about the judicious use water to educate about water harvesting through groundwater recharging and retention of water in pond, lakes, small reservoirs.
The writer is Former Senior Scientist, Central Pollution Control Board and is from A-139, Survey Park, Santoshpur, Kolkata-700075 and can be reached at 919432370163 & 916290099509 or [email protected]