Abstract
Abstract. Climate change affects the global water cycle and has the potential to alter water availability for food–energy–water production, and for ecosystems services, on regional and local scales. An understanding of these effects is crucial for assessing future water availability, and for the development of sustainable management plans. Here, we investigate the influence of anticipated climate change on water security in the Jaguari Basin, which is the main source of freshwater for 9 million people in the São Paulo metropolitan region (SPMR). First, we calibrate and evaluate a hydrological model using daily observed data, obtaining satisfactory coefficient of determination and Kling–Gupta efficiency values for both periods. To represent possible climate change scenarios up to 2095, we consider two International Panel on Climate Change (IPCC) Representative Concentration Pathways (RCP4.5 and RCP8.5) and use an ensemble of future projections generated by 17 general circulation models (GCMs). These data were used to drive the hydrological model to generate projected scenarios of streamflow. We then used indicators of water scarcity and vulnerability to carry out a quantitative analysis of provision probability. Our results indicate that streamflow can be expected to exhibit increased interannual variability, significant increases in flow rate between January and March, and a 2-month extension of the hydrological dry season (currently June to September) until November. The latter includes a more than a 35 % reduction in streamflow during September through November (with a > 50 % reduction in October). Our findings indicate an increased risk of floods and droughts accompanied by an expansion of the basin critical period, and our analysis of the water security indices identifies October and November as the most vulnerable months. Overall, our analysis exposes the fragility of water security in the São Paulo metropolitan region, and provides valuable technical and scientific information that can be used to guide regional plans and strategies to cope with potential future water scarcity.
Highlights
Achieving a sustainable equilibrium between water availability and demand is among the major socio-environmental challenges faced by the 21st century (Rockström et al, 2009; Vörösmarty et al, 2010)
During the historical period the highest streamflows occurred in February, whereas in the projected future periods the highest values shift to January, reinforcing the fact that projected climate change does not just affect the intensity and duration of events and their distribution and periodicity
We have presented a technical and scientific strategy for generating information to be used as guidance in the development of plans and strategies for dealing with anticipated water scarcity
Summary
Achieving a sustainable equilibrium between water availability and demand is among the major socio-environmental challenges faced by the 21st century (Rockström et al, 2009; Vörösmarty et al, 2010). Demand for water is increasing due to population growth and the need for agricultural and energy production to keep pace (FAO, 2015; IEA, 2016; United Nations, 2015). The percentage of water consumption for energy and food production is expected to increase dramatically (IEA, 2011). It is estimated that by 2050 there will be a 100 % increase in demand for food production in developing countries (FAO, 2011). Changes in climate tend to increase existing and future risks associated with the management of water resource systems (Mandal and Simonovic, 2017). These effects are expected to be evident
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