28.1 Introduction
According to the United Nations World Water Development Report (WWDR) (WWAP 2015), the global water demand is significantly influenced by population growth, urbanization, and the security policies for food and energy in the developing countries. The availability of water resources varies in different areas of the globe due to the unpredictable distribution of precipitation and runoff. In addition, due to a combination of factors including climate change, inefficient water supply and distribution systems, and water pollution, an increase in the population will aggravate the distribution and availability of water resources, which in turn will affect the per capita water availability (Eslamian and Okhravi 2015). Based on the Food and Agriculture Organization (FAO) AQUASTAT dataset (2018), most of the developing countries come under the vulnerability to scarcity zone according to the per capita water availability. Due to the variability in the surface water, groundwater use has augmented and interestingly, India, China, Nepal, and Pakistan extract nearly half the world's total groundwater (WWAP 2015). In this sense, it is understood that developing countries are going to be affected by climate change and its variability. To minimize the adverse effect of water scarcity, water harvesting is one of the adaptive measures and in the present study, India, as a developing country, is considered to evaluate the possibility of water harvesting under climate change and its variability. The water scarcity not only influences the water resources of the country but it also has a significant impact on the social and cultural aspects of mankind.
The inherent vagueness and adversity of climate change bring forward the complex and extreme phenomena like floods, cyclones, high and intense precipitation, heat waves, droughts, etc., and challenges people to search for an appropriate mitigation and adaptation strategy as the climate and culture are interlinked (Pandey et al. 2003). The occurrence of extreme climate events results in population dislocation and migration to safer and productive localities (deMenocal and Peter 2001; Núñez et al. 2002). In addition, human migration as a survival strategy to climate change variability is noticed in various parts of the globe, including Africa, Australia, and South America (deMenocal and Peter 2001; Polyak and Asmerom 2001; Núñez et al. 2002; Tyson et al. 2002; Bowler et al. 2003). Verschuren et al. (2000) reported that based on the scientific evidences and oral lore there exists a strong association among cultural development, climate change, and water stress. However, Pandey et al. (2003) suggested to rehabilitate the dwelling environment through effective adaptation strategies to improve water harvesting as quoted in the Indian proverb, “Capture rain where it rains” (Pandey 2001). The progress toward sustainability and resilience requires a complete knowledge of climate variability and corresponding adaptation by human society. A comprehensive study regarding the widespread rainwater harvesting with respect to the climate variability in India from 4500 BCE to 1999 CE is detailed by Pandey et al. (2003) and the readers were advised to follow the article. In addition, Pandey et al. (2003) explored the evidence of correlation between the water harvesting structures and climate variability like aridity and drought conditions, and found it to be significant. Based on the historical evidence, it is worth mentioning that climate change and its variability affects all aspects of human life and hence we must work collectively together and stop procrastinating.
In India, rainfall is a finite and main source of freshwater that needs proper management for effective use. Realizing the urgency, India has a rich history of preserving surplus water, using water harvesting structures since 4500 BCE. Water has been harvested from the rainfall directly, or by diverting the water from the flooded rivers, and the constructional design of the water harvesting structures depends on the variability of the precipitation and available resources. Therefore, India has its own water harvesting methodologies that imitate the geographical and cultural uniqueness. However, due to the improper management of the water harvesting structures, along with the alarming climate change variability (e.g. erratic rainfall), the problem has been manifested in many ways. In addition, due to cultural, economic, and political factors, the traditional water harvesting structures have become unused or have lost their significance in the present scenario (Pandey et al. 2003).
Water availability has significant impacts in many parts of the India, which in turn puts immense pressure on the fragile agricultural system of the country. Therefore, it is necessary to assess climate change variability to rejuvenate the existing water harvesting structures and evaluate the possibility of water harvesting to meet the demands of the communities for the present and possible future climate change scenarios. Though climate change is a global phenomenon, it has varying degrees of regional impacts (Goyal and Rao 2018). Although there are various schools of thought relating to the different climate change causes, viz. greenhouse gases emissions, aerosols, changes in albedo, and solar irradiance, climate change is real and happening right now. In the prevailing adverse consequences of climate change and its variability, it is indispensable to evaluate and analyze the change ability of available water resources for better management practices and adaptation strategies. Climate change as a potential “risk multiplier” has significant impact on developing countries, where the economical and societal development are closely associated with the agriculture and water resources (Pande et al. 2014). Within this context, the demand of water resources has increased over the years due to the increase in the population, urbanization, agricultural demand, and economic growth over India (Mall et al. 2006). Also, Mall et al. advocated that change in the land use pattern, over exploitation of water storage are modifying the hydrolo...
