Fourth of a five-part series on Rotterdam’s efforts to become a sustainable and “climate-proof” city.
Facing increased flood risks as the world’s climate changes, Rotterdam is implementing a comprehensive flood-protection strategy.
Although accessibility to the sea and navigable inland waterways are largely responsible for Rotterdam’s prosperity, the city’s location makes it especially vulnerable to rising seas and extreme weather.
Situated on the Rhine–Meuse–Schelde river delta, Rotterdam is Europe’s lowest lying city. Parts of its delta lie nearly 7 meters (23 feet) below sea level. The city is thus exposed to water from the ocean, the Meuse River, groundwater, and rain.
The city’s current drainage system will not be able to cope with the prolonged downpours and higher peak river flows that climate change will bring. Heavy rains already often cause minor flooding. So, unless something is done to prevent it, more serious flooding will eventually ensue.
Large parts of the city are located beyond its dikes and its North Sea storm surge barrier. Tens of thousands of people also live in proximity to the Meuse River. “Doing nothing is not an option,” says Arnoud Molenaar, the head and chief resilience officer of the Rotterdam Climate Proof (RCP) program.
The Rotterdam Climate Proof Program
Adopted in 2008, the fundamental purpose of the RCP program, part of the more comprehensive Rotterdam Climate Initiative (RCI), is to make sure the city stays safe, accessible, habitable, and attractive to residents and investors, despite the impacts of climate change. Focused on climate adaptation, RCP was established to ensure the resilience of the city’s infrastructure and services while maximizing the economic co-benefits of any adaptation measures. The program’s goal is to make Rotterdam fully “climate proof” by 2025.
The Challenges Ahead
As climate change occurs, Rotterdam will need its infrastructure and critical systems to function so essential public utility services remain available. However, protecting the city will not be easy: its water purification plant, power plants, and railways are all outside the city’s diked core. Rotterdam’s port will also need to remain operational and accessible, as will the city itself.
The outer dikes to the north and south of the Meuse are designed to protect against once in 10,000-year and once in 4,000-year floods, respectively. Thus, Rotterdam and its port are commonly regarded as “one of the safest delta cities in the world.” However, expert consultants note that by 2100, these dikes will no longer be adequate.
Although above sea level, the areas of Rotterdam beyond its outer dikes are susceptible to flooding. Utility corridors for the city’s diked areas permeate this region, so flooding beyond the embankments can disrupt the inner city. If nothing is done, then damage to buildings outside the diked area would double and triple by 2050 and 2100, respectively.
A Systems Approach to Flood Protection
To reinforce and augment the infrastructure, RCP performed a risk-and-damage assessment of the city’s vulnerabilities to climate change. Results showed that to keep vital systems robust under new climate conditions, the city had to adopt a systems approach. Thus, it analyzed its water management systems as a whole and is striving to identify new ways to relieve stress on the system during periods of increased water flows.
To this end, the city is undertaking numerous small-scale water management projects, including below-grade water plazas, water infiltration zones, and tree and vegetation planting. These public works slow the release of water during extreme rainfall events to protect Rotterdam’s sewer system from overloading and public areas from flooding.
A Coordinated Approach to Flood Protection
RCP uses a coordinated approach in the city’s outer-dike area that includes spatial planning to raise ground elevations, dike reinforcements, and other design and retrofit measures. The city is also studying the feasibility of building floating homes; verifying that evacuation routes are adequate; and informing the public of the challenges of climate change, the actions they can take, and their responsibilities in times of crisis. As a last resort, citizens are being encouraged to be self-reliant during future climate-related emergencies.
Governance and Leadership
Although public pronouncements of RCP are decidedly upbeat, Rotterdam officials were short on details about how much the city was spending on its program and unable to provide specifics on flood reduction efforts to date and what risks would remain in 2025 when the city is supposedly “climate proof.” Hopefully, the measures that the city puts in place will be equal to the challenges ahead.