Abstract: The article introduces urban design as a tool to test the storm-water storage needs of two alternative development scenarios for the eastern portion of Pazhou Island in the Pearl River Delta. The island is located directly to the south of Guangzhou’s central area. As reflected in historical maps, the island was formed by longterm accretion of river sediments around two rock outcrops between the front channel of the Northern Pearl River and the Whampoa Canal. Pazhou Island’s strategic proximity to Guangzhou’s financial district has made it a prime location for urban development, and the western portion of the island became part of a media and new technology district in the second decade of the 21st century. In light of current proposals to turn the eastern part of the island into a major commercial concentration of the new Pearl River Bay polycentric region, we contrast two development scenarios and analyzed how well each could provide for the water storage needs required during heavy typhoonal rains, and the protections needed against riverine flooding and tidal surges. One scenario would develop all available land, while the other would leave currently low-lying land available as wetlands that can be flooded during storm events. We based our calculation of storm-water storage needs on a 1981—2017 maximum. daily precipitation record. We conclude that 100 year rainfall can be stored on 80 hm2 existing lowlying wet-lands, 1.34m deep. We end the article with recommendations to the regional government for adaptable designs of the island perimeter for flood protection and for adaptable design of water storage in low-lying unbuilt areas thus largely avoiding the need for expensive water storage chambers or vaults under roads that would become necessary, if all available land would be developed. We also delineate alternative future conditions for the villages on the island, including a fishing village that is openly exposed to typhoonal wind and waves along the island’s south-eastern shore.