1 June 2015

Flood resilience is a must for delta cities

By Ruben Dahm* , Deltares, Delft, the Netherlands (ruben.dahm@deltares.nl)

Conventional methods of flood protection such as levees are no longer adequate against the increased risk of flooding in Asian delta cities.

We call for a multipronged approach that focuses on long-term, sustainable solutions to increase these cities’ resilience to flooding (see also L. Giosan et al. Nature 516, 31–33; 2014). In October, Ho Chi Minh City in Vietnam experienced recordbreaking flood levels in the Saigon River for the fifth consecutive year and for the eighth time in the past decade. Among the contributing factors are massive urban development, reduced river-storage capacity, land subsidence from unregulated groundwater extraction, extreme storm events and rising sea levels. Similar disruptions in Beijing, Jakarta and Manila have also led to catastrophic floods. Several strategies exist to increase resilience against flooding. These include developing urban infrastructure to decrease the effects of extreme rainfall (for example,
by incorporating sustainable living green roofs and making pavements permeable); building in harmony with natural-systems dynamics, as in the Room for the River (go.nature.com/hqjld5)
and Sand Motor (go.nature.com/e24ecq) projects in the Netherlands; and incorporating flood-risk forecasts for downstream urban areas into reservoir management.

*On behalf of 4 correspondents (see
go.nature.com/qmy9vg for full list).

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