Implications of Climate Change on Water Resource Management in Megacities in Developing Countries: Mexico City Case Study

Abstract

More than half of the world’s population currently lives in urban areas. The fastest growing megacities are occurring mainly in developing countries, where stresses on water systems already pose major challenges for governments and water utilities. Climate change is expected to further burden water resource management, putting at risk governments’ ability to guarantee secure supplies and sustainable development. In this study, the significance of assessing the implications of climate change on water resources in megacities as an important component of the adaptation process is explored. The Mexico City Metropolitan Area (MCMA), one of the largest cities in the world, is presented as a case study. The downscaled outputs of the General Circulation Model GFDLCM2a for the A1B and B1 gas emissions scenarios for the period 2046–2081 and a statistical model were used to simulate the likely impacts of climate change in water resources and domestic water demand. The results showed that an increase in temperature and changes in precipitation patterns could increase household water demand for both scenarios, between 0.8% and 6.3% in the MCMA. The future projections also estimated increases of 150% and 200% in events with rainfall intensity of more than 60 mm d^-1 and 70 mm d^-1 respectively, drawing attention to the critical impacts these changes may have on flood events. Despite the uncertainty of models projections, future climate change scenarios have proven to be a flexible guide to identify vulnerabilities of water resources and support strategic adaptation planning. In order to increase their adaptive capacity and resilience to the effects of an uncertain climate change, megacities should consider implementing an integrated water resources management approach that creates opportunities through adequate policies, new technologies, flexible frameworks and innovative actions.