Trial by typhoon shows city's resilience

Water, water everywhere

Following the torrential rain, floodwaters inundated streets, underpasses, and residential compounds across the city, particularly in central downtown districts, including the iconic, tree-lined Wukang Road area.

"The waterlogging in some areas during recent typhoons cannot be attributed to any single factor," explained Wu Meng, deputy director of the circular economy and green development research office at the Shanghai Academy of Social Sciences' Institute of Ecology and Sustainable Development.

Wu said the heavy rainstorms were the direct cause of the standing water. Shanghai sits on flat land right next to the sea and all its rivers are connected to the rise, and fall of tides, which hinders rainwater from draining out of the city easily.

"Contradictions between dense urban development and available water storage space are another reason," Wu added. Water storage space refers to soil, rivers, lakes, drainage networks and sponge facilities that can hold rainwater before flooding occurs.

Shanghai uses a multi-tier system for urban flood control.

Standard underground pipe networks handle routine rainstorms, while surface river networks and pump-gate systems manage regional drainage.

In coastal areas and along riverbanks, sea walls and levees defend against storm surges. For extreme events that exceed standard engineering designs, the city relies on above-ground water storage, emergency pumping and adaptive risk management to mitigate damage.

Currently, about 70 percent of Shanghai's central urban area is designed to withstand a storm recurrence, or return period, of every three to five years, equating to an hourly rainfall intensity between 51.2 and 58 mm.

Dolphin, however, far surpassed these capacities.

Sun Xiaofeng, deputy director of the comprehensive planning department of the Shanghai Water Authority, explained to Jiefang Daily that even infrastructure built to a 20-year return period standard cannot guarantee the complete absence of standing water under the intensity of a typhoon as strong as Dolphin.

Dense development in central districts has also left limited land for open water bodies and retention basins, forcing neighborhoods to rely largely on underground pipe networks.

"Expecting zero flooding anywhere at any time during extreme rainstorms is neither realistic nor economical," Wu said.

"Modern urban drainage aims for minimal flooding within design standards. For extreme, record-breaking storms, it lets small, controlled puddles stay temporarily — but it must never cause deaths, flood underground spaces, or shut down the city's key services."