Low Impact Development of City Wall-Canal System from Urban Segregator to Green Archival Linkage—“Sponge City” Rejuvenation Design of Historic Eastern Water Gate Area of Nanjing

The city wall-canal system forms the structure of Nanjing’s landscape pattern. However modern development not only erodes the public space along it, pollutes the Qinhuai River, but also results in urban waterlogging. This article starts from the study of the area inside and around city wall of Nanjing and proposed the “Green Belts” strategy as the green infrastructure to stich the broken city wall-canal system on urban level. On local level, it zooms in the eastern water gate district as the most contentious site based on a series of site analysis and proposes the “cut-remove-suture-grow” strategy. As to the detailed design, this article proposes the concept of nine water processing systems for storm water and flood management and rainwater harvesting integrated with the conservation of city wall under the low impact development mode. Then the concept is further developed through the detailed design of 4 subdivided sites.