of India in the form of fewer rainy days, but more extreme rainfall events. This is resulting in an increased amount of rainfall in each event, leading to significant flooding. Most of the global models suggest that Indian summer monsoons will intensify. The timing of seasonal variation may also shift, causing a drying during the late summer growing season. There has been a significant change in precipitation and temperature pattern in India from 2000 to 2015. This could indicate a signature of climate change in India (Goyal and Surampalli 2018).
1.4.2 Glaciers
Around 9040 glaciers have been reported in India, covering nearly 18 528 km2 in the Indus, Ganges, and Brahmaputra basins (Sangewar et al. 2009; Sharma et al. 2013). Any changes in a glacier can affect river run‐off and the water availability in the Himalayan rivers (Indus, Ganges, and Brahmaputra) and agricultural practices in India. The annual rate of glacial shrinkage is reported to be nearly 0.2–0.7% in the Indian Himalayan region for 11 river basins during the period 1960–2004 with a mean extent of 0.32–1.40 km2 (Kulkarni et al. 2011; Bolch et al. 2012). Ramanathan (2011) reported the mass balance of Chhota Shigri glacier (15.7 km2), located in the Chandra River basin of Himachal Pradesh, showed a net loss of about 1000 m from 2002–2009. The flow diagram demonstrating the impact of climate change on glaciers is depicted in Figure 1.3.
Figure 1.1 Impact of climate change on water resources.
Figure 1.2 Decade‐wise average rainfall annual data of India.
(Source: Envi Stats India 2018; https://data.gov.in/keywords/annual‐rainfall.)
In India, climate change is expected to affect Himalayan rivers (Ganges and Brahmaputra) due to the faster rate of melting of Himalayan glaciers. Himalayan glaciers are known as the “Water Tower of Asia,” a major source of water in all major Asian rivers (Shiva 2009). As per the Intergovernmental Panel on Climate Change (IPCC), these glaciers are receding faster than any other part of the world (IPCC 2007). The Gangotri glacier (source of the river Ganga), receded 20–23 miles/year, whereas other glaciers can retreat more than 30 miles/year as a result of rising temperatures (Shiva 2009). If the conditions continue, glaciers will melt quicker and no glaciers will be left to supply water for the entire year, then rivers like Brahmaputra and Ganges will become seasonal rivers. In the monsoon season, the combination of the heavy melting of glaciers and intense heavy rainfall for fewer days may create a flash flood‐like situation. On the other hand, reduced rainfall in the rest of the year may lead to drought in some regions. Chevaturi et al. (2016) illustrated the climate change impact on the northern region of Ladakh. The Ladakh area is unique due to its location in high altitude, dry desert with cold temperatures, and water flows to the mountains. Research showed a warming trend with reduced seasonal precipitation, making it highly sensitive to temperature changes.
Figure 1.3 The flow diagram of the impact of climate change on glaciers.
(Source: Pandey and Venkataraman 2012.)
1.4.3 Sea Level
Rising sea levels and flooding are the biggest threats of climate change. As temperature rises, ice melts and water level rises. This threatens to engulf coastal areas and cause mass displacement and loss of life. Initial predictions expected a sea‐level rise of over 59 cm by 2100, but current rates will likely exceed this by a wide margin. According to Pandve (2010), a sea‐level rise of 1 m would inundate up to 5763 km of India, as many cities lie only a few feet above sea level, making severe coastal floods.
1.4.4 Groundwater
Groundwater resources are affected due to an inadequate amount of water percolating down to aquifers due to reduced rainfall. The increased atmospheric temperature also increases the rate of evapotranspiration, which leads to a reduction in the actual amount of groundwater available for human use. India extracts 1000 km3 of groundwater annually, which is 25% of groundwater at a global level (Mukherji 2019).
Climate change affects Indian water resources through warming of the atmosphere, alterations in the hydrologic cycle, melting of glaciers, rising sea levels, and changes in precipitation patterns (amount, timing, and intensity). The alteration of monsoon patterns decreases rainy days but increases the amount of rainfall. Himalayan glaciers are receding faster than any other part of the world. Further, the combined impacts of changes in precipitation patterns, glaciers melting, and sea‐level rise has caused flood‐like situations in different parts of the country. One noticeable thing, if the conditions continue, glaciers will melt quicker and no glaciers will be left to supply water for the entire year, then rivers like Brahmaputra and Ganges will become seasonal rivers.
1.5 Impact of Climate Change on the Quality of Water Resources
The impact of climate change on water quality has not gained much concern as an emerging topic in water research to date. However, possible effects are discussed with the association of health as depicted in Figure 1.4. Floods and droughts also affect the surface water qualitatively (in terms of pollutant concentration) and quantitatively. Whenever drought condition persists, the groundwater resources are depleted and the concentration of the pollutants are elevated in the residual water (IPCC 2007). Changes in precipitation or hydrological pattern and increased run‐off can result in the rise of pathogens and contaminants in water bodies. Increased frequency and intensity of rainfall may cause more water pollution due to run‐off water. The decrease in dissolved oxygen in water due to the increase in the temperature of the water is the direct consequence of climate change on water quality. Further, the concentration of dissolved carbon, phosphates, nitrates, and micropollutants are also directly altered as a consequence of climate change and they produce an adverse impact on health (Delpla et al. 2009).
Climate change is not only expected to influence the quantity of groundwater but also to influence the quality of groundwater (Dragoni and Sukhija 2008). Water recharges during an arid period contain a high concentration of salts and increases total dissolved solids (TDS). However, in a wet period, the reverse phenomena can occur. Climate change increases sea surface temperatures and results in rising sea levels. Further, rising sea levels may lead to saltwater intrusion into coastal aquifers, which influences groundwater quality and contaminates drinking water sources whenever salty water percolates into the freshwater system. It is very difficult to reverse the process. Climate change influences the amount or pattern of precipitation, resulting in a flood‐like situation and affects groundwater quality through the release of agrochemicals/industrial wastes from soil to groundwater.
Figure 1.4 Impact of climate change on water quality and its association with health.
Climate change affects water quality