Climate change impacts on water resources and selected water use sectors

Abstract

Climate change is now largely accepted as a real, pressing, and truly global problem, and scientific evidence for global warming is now considered irrevocable (Allison et al. 2009). Understanding the potential impacts of current and future climate conditions on hydrological processes is gaining more impetus in the present day because of the social and political implications of water. The Fourth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC 2007) has addressed many previous concerns pertaining to the credibility of climate change in scientific and policy discussions. There is an increasing consensus among the scientific community that climate change will have a significant effect on water resources (Bates et al. 2008; Cromwell et al. 2009; Xu et al. 2007; etc.). Listed hereafter is a summary of the various potential impacts of climate change on water supply systems (Arnell and Delaney 2006; Bates et al. 2008): It is expected to cause an increase in volume of precipitation and average runoff in high latitudes and part of the tropics and a decreased volume in some subtropical and lower latitude regions. It is likely to alter the reliability of raw water sources and supply infrastructure (e.g., dams, reservoirs) by changing the magnitude and frequency of flows. It may alter the demand of water and the ability to meet these demands, particularly at times of peak demand. By 2050s, the area of land subjected to water stress would be two times the area that is not stressed. For global assessment, water stress occurs when the per capita availability of water is less than 1000 m3/year or when the ratio of water withdrawals to long-term annual runoff exceeds 0.4. It is likely to cause an increase in the number of extreme events like floods and droughts. It may alter the raw water quality because of rise in water temperatures and thereby the ability to treat raw water to potable standards. Current management practices worldwide may not be able to cope up with the ill effects of climate change.