Uncertainties in water supplies due to changing climate and extreme weather events

Water is an essential resource for ecosystems, daily needs of humans and economic development. Rightly water is closely connected with food provision and energy production (Water-Food-Energy nexus) and hence uncertainties in water supply cannot be discussed in isolation. Currently several regions and countries are heavily impacted by the water challenges but the scope and complexity widely vary. At the current level of demand from economic activity and population, about 53% of the population are living in the places where water is scarce or or close to reaching water scarcity. Further, increasing population and progressive increase in the economic activities increase the water demand hence, undermines water scarcity. Even at current level of population and economic activity, managing the risks associated with extreme events are difficult. With the global warming, frequency of extreme events is on rise; as a result, severe damage to the basic livelihood of wider spectrum of people across the globe could be felt. While the climate models accurately predict the atmospheric temperature, it is still difficult to predict rainfall and hence this is the most important factor for uncertainty. These uncertainties can then lead to uncertainty in water quantity, water quality, ecological functions, agriculture (food production), energy production and drinking water availability. This chapter explores the above aspects systematically to provide a comprehensive review of the available literature. In addition, an effort is made to point possible adaptation measures to mitigate possible impacts.