Integrating Blue and Green infrastructure in Megacities: A Case Study of Shanghai

Over the last 30 years Shanghai has seen rapid urbanization and population growth and is currently home to 24.2 million people. By 2018 the urban area had increased by 7 to 8 times compared to 1985. This urban development has increased the impermeable area across the urban catchment, reducing the amount of green space and opportunities for water to infiltrate the soil. It has resulted in substantial increases in stormwater runoff - of the order of 50% compared to the 1985 levels - across the city which causes significant flooding and contributes to river pollution. In order to address these issues, and following an international design competition, the Shanghai Water Authority appointed Arup to develop a range of drainage solutions for the city. Following an 11-month collaboration with the Shanghai Urban Construction Design & Research Institute, Arup developed a comprehensive drainage masterplan for the city of Shanghai, which was endorsed by national Chinese experts and signed off by the Shanghai Water Bureau on 31 August 2019. The plan, which covers an area of 640 square km (247 square miles), challenges the traditional way of thinking and proposes a visionary blue, green and grey approach for the city, and integrates innovative strategies to achieve the city's design goals, improve wellbeing, serve urban redevelopment and enhance water resilience.