Pollutants and Water Management. Группа авторов

to the rise of temperature, while alternations to the hydrological cycle increase pathogens and contaminants in surface water. Groundwater quality has been indirectly affected by climate change due to increases in TDS, salts, and other contaminants. Further, rising sea levels may lead to saltwater percolation in coastal aquifers, which influences groundwater quality.

1.6 The Health Perspective in Association with Water Security and Climate Change

As per the WHO (2018), in the period between 2030 and 2050, climate change could be the reason for approximately 250 000 additional deaths per year by malnutrition, malaria, diarrhea, and heat stress. The additional health costs by 2030 are estimated to project USD 2–4 billion/year. Climate change affects health through polluted air, unsafe drinking water, insufficient food, and shelter safety. Extreme high air temperatures directly affect cardiovascular and respiratory systems, particularly to older adults. In Europe, more than 70 000 deaths were recorded under the influence of a summer heatwave during 2003 (Robine et al. 2008). High temperature also increases ozone levels and other pollutants in the air, leading to cardiovascular and respiratory diseases. The levels of pollen and other aerial allergens are high in extreme temperature/heat. This can trigger asthma, which affects nearly 300 million people in the world (WHO 2018). Apart from this, climate change has a high impact on water‐related diseases. The nonuniform rainfall patterns are likely to affect freshwater and make it unsafe for humans. This water can compromise hygiene and increase the risk of diarrheal disease, which kills over 500 000 children aged under five years, every year (IPCC 2014).

      India is one of the major countries that suffers from water‐related diseases. The security of drinking water ensures the prevention and control of water‐borne diseases. As per the WHO assessment, around 37.7 million people in India are affected by water‐borne diseases every year, and among them, 75% are children (Khurana and Sen 2009). The World Bank has also estimated that 21% of communicable diseases in India are related to unsafe water. The impact of climate change increases the risks of water‐borne diseases like cholera, malaria, and dengue by warming of the climate and intense rainfall. A UN report stated that more than one lakh people die annually from water‐borne diseases and 73 working days are lost due to water‐borne diseases. Another report stated that 1.5 million children die annually from diarrhea (Khurana and Sen 2009). Apart from water‐borne diseases, cancer, cardiovascular diseases, mental disorders, and other diseases are reported due to probable contaminants found in water (Kaur et al. 2019). A resulting economic burden of $600 million has been estimated per year due to water‐borne diseases. Further, climate change makes the situation more critical. Rising temperatures often bring negative impacts to human health and life. The incidences of water‐borne diseases like cholera, diarrhea, and so on,. become more prevalent in warmer climates (Figure 1.4). Vector‐borne diseases like malaria can thrive when the temperature increases as a result of global warming. It is also estimated that up to 2050, the malaria vector will shift away from central regions towards southwestern and northern states due to the variation of rainfall (Kiszewski et al. 2004). Malaria kills over 400 000 people every year on the global level.

      Vector‐borne diseases like dengue also increase in warm and rainy climate due to the increasing mosquito population. The Aedes mosquito vector of dengue is also highly sensitive to climate conditions, and studies suggest that climate change is likely to increase exposure to dengue. Apart from the risks caused by increased temperature, intense rainfall could result in floods and waterlogging in several places. Waterlogged areas will then become the potential grounds for mosquitoes breeding. In India, especially in the Ganges basin, poor habitats have no choice for drinking and cooking other than using the polluted water of rivers. This results in numerous diseases. Among these diseases, stomach infections like diarrhea and dysentery are common. People living in rural areas and urban slums will be more vulnerable to diseases and infections because they do not have access to piped water and cannot afford to buy clean water. Water shortages have an enormously devastating impact on human health, including malnutrition, pathogen or chemical loading, and infectious diseases from water contamination. In the future, this cycle of diseases will place an enormous burden on the government, who will have to scramble to provide health care for all those affected and have to take preventive measures to control the situation from worsening.

      Climate change affects health through polluted air, unsafe drinking water, insufficient food, and shelter safety. The nonuniform rainfall patterns are likely to affect freshwater in India and make it unsafe for humans. This water can compromise hygiene and increase the risk of diarrheal disease, in these cases, children are the main sufferers. Further, the impact of climate change also increases the risks of water and vector‐borne diseases like cholera, malaria, and dengue by warming of the climate and intense rainfall.

1.7 Major Challenges to Water Security

      1.7.1 Water Demand for the Future

There are several reports published by national and international agencies on the current and future demand of water (Tables 1.1 and 1.5) for India. Based on these reports, it can be analyzed that meeting the water supply‐demand of India will be a serious challenge. The most serious concern is the growing population, which is likely to increase to 1.4 billion by 2050. To meet food security, the agricultural sector also needs a huge amount of water.

      1.7.2 Overexploitation of Groundwater

      The water table in India is depleting at a rate of 0.4–0.6 m per year. Out of the total assessment units (blocks/taluks/mandals/districts/firkas/valleys), nearly 17.5, 4.5, 14, and 64% units have been categorized as overexploited, critical, semi‐critical, and safe, respectively (CGWB 2017). So, preventing the overexploitation of groundwater will be another challenge.

      1.7.3 Management of Water Resources

       Water availability: The water resources of India have a large gap between potential and availability. The potential of water resources has been estimated at 1869 BCM and annual precipitation is 4000 BCM. Out of a total potential 1869 BCM, India uses 1123 BCM of water. The topographical and large temporal variability and regional mismatch between water availability and demands are the major reasons for the difference between potential and availability (Jain 2019).

       Flood management: The large variability of rainfall in space and time in India causes flooding in different parts of the country. Indian rivers carry more than 70% of their annual flow in four months during the monsoon period. There is an essential need to conserve flood water and flows for the growing demands of water in the country. Flood management can also play a key role in groundwater recharge and drought management. Nearly 500 BCM of water has been estimated through flood flows in Indian rivers (Jain 2019). In the current scenario, the management of storage flood water is not sufficient. The management of storage flood water can be used to meet growing demands throughout the year. It will also help in water‐related disasters like floods and droughts.Table 1.5 International reports on current and future demands of water of India.Source: IDSA (2010).World Bank Report 1999YearExpected demandYearPer capita water availability1997552 BCM19475000 m3 per year20251050 BCM19972000 m3 per year20251500 m3 per yearThe Mckinsey Report 20092009740 billion m320301.5 trillion m3

       Water transfer between water enriched and water‐stressed regions: India has large temporal and geographical variability about water availability. The transfer of water between water surplus regions to deficit regions could be a very effective approach in meeting the demand of the entire country.

       Recycle and reuse: In the current scenario, less of the urban water supply is recycled and reused, and a large quantity of water is wasted. Around 40% of the water in some cities in India is wasted due to leakage or theft. For instance, the Arab states treat