UN World Water Day and nature based solutions: How about…?

Responsible Use of Natural Resources 21 March 2017 Henrik Søgård Olsen

Ramboll celebrates the UN World Water Day with ideas for nature-based solutions that might be imaginative, but not impossible to implement.

14 min

22 March is the UN World Water Day. Under the slogan ‘The Answer is Nature’ this year’s focus is on how we can reduce floods, droughts and water pollution by using solutions we already find in nature. 

Water experts and landscape architectures from Ramboll are celebrating the day by asking “how about?” and suggesting ideas for nature-based solutions that might be a little far-fetched but not totally impossible to implement.


China has armored its coastline over the past several decades, building sea walls and turning more than half of its marine wetlands into solid ground for urban development. Nonetheless, cities like Shanghai are still under huge risk of flooding from storm surge and sea level rise. Additionally, the impact of these developments has had severe impact on almost 500 species of migratory birds.

How about, combining the Chinese megatrends of Forest City, Sponge City and Eco City to create a comprehensive ecological wildlife corridor and reef around Shanghai while also increase the protection against storm surge.


  • New ecological habitat for wildlife only

  • Reef barrier will reduce impact of storm surge

  • Opportunity to close barrier in future with further infill to increase protection

  • Be a catalyst for big changes in urban biodiversity and ecology through Forest City matrix on a large scale

  • Utilize Sponge City principles to manage stormwater in green infrastructure of Forest City areas


Eindhoven is located in the Netherlands on a former swamp by the intersect of the rivers Dommel and Gender. Over the years many natural streams have been removed from this area. This, along with the major reduction in the groundwater abstraction has caused the water table to rise. The threat from below combined with the threats of heavier rainfall and flooding of local rivers mean Eindhoven is threatened by water from all sides.

Furthermore, the general physical state of Eindhoven is at a point, where urban regeneration is much needed.

How about, reintroducing the water to the urban environment, creating a rehydrated Eindhoven? The future resiliency builds on 2 major principles;

  1. Keep a constant flow of water through the city - lowering of the groundwater table and creating a blooming city center, consisting of streams and channels connecting blue hot spots throughout the city.

  2. Creating space outside the city for the river to expand - by creating multifunctional natural areas outside the city and controlling the amount of water flowing into it, the city can be kept safe along with providing attractive natural areas for citizens and wildlife.
    How about, using water as the driver for urban revitalization and to create a new identity for Eindhoven?


  • Reducing risk of flooding.

  • Creating a healthy blue-green urban environment.

  • Creating attractive natural areas just outside the city.

  • Enhancing potential for biodiversity.

  • Utilize the reintroduction of water as a driver for urban redevelopment.


In the devastating storm of July 2011, 150mm of rain fell in just 2 hours over the whole city of Copenhagen. In an ideal future, Copenhagen will have adapted to be able to manage this kind of volume through creating innovative surface detention across the city. A quick calculation would tell you that equates to almost 15,000,000m3 of volume to be created…but also 15,000,000m3 of soil to be excavated.

Additionally, flooding is also coming from the sea from storm surges and with the increasing risk of sea level rise. A common solution to this is to build raised protection using soil.
How about, using this 15000000m3 of soil to create a vast hill near the coastline of Copenhagen. On day one, it will bring a long list of short-term benefits to the city while in the long run acting as a soil reserve for future coastal flood protection.


  • Highest point in Denmark now located in the capital of Copenhagen

  • Nature-based storm-surge protection

  • Panoramic views
    o To Sweden
    o To Køge Bay
    o To Copenhagen
    o Across the Kalvebod Fælled (bird watching)

  • New Activities to Denmark
    o Hiking
    o Skiing
    o Mountain Biking

  • New habitats and ecology

  • New destination
    o Tourism
    o Pit-stop for fælled loop


During monsoon season, Bangladesh becomes extremely vulnerable to flooding. In the biggest rain events the damage and destruction cause leaves millions homeless and facilities destroyed. With Dhaka being one of the most populous areas and surrounded by large rivers, it is high risk city in need of a drastic solution to this drastic problem.

How about, digging 1000's of detention ponds within Dhaka’s urban core to mitigate chronic flood events. This land may be moved outside its perimeter embankment to create islands of “high ground” safe for housing the climate refugees from Bangladesh’s coast-land.  This massive shift in ground could help adapt Dhaka to the climate change effects of increasing storm waters and increasing migrant populations from the rural areas.


  • Fortifying the perimeter around the city to protect against river flooding

  • Raised ground level outside of the perimeter to ensure city growth and development can continue

  • Decentralising flooding by using lots of small scale solutions instead of one central solution

  • Potential synergies for rainwater harvesting in local areas due to decentralized solution

All the ideas above are 100 % imaginative and not concretized or thoroughly thought out. However, we are always ready to go into more detailed discussion on value-creating nature-based solutions of any kind.


 “One, if by land, and two, if by sea” ~Henry W Longfellow, Paul Revere’s Ride.

Globally, extreme weather events are occurring with increasing frequency. In Boston, it seems every weekend this winter has been declared a “state of emergency” in anticipation of an incoming nor’easter, aka a winter hurricane or blizzard.  In fact, tonight we are in the midst of the fourth nor’easter this month. But what is typically a fun, snow day for most people in the US, the implications of winter storms, and all storms in Boston for that matter, are quite serious.

On a normal, sunny day in Boston, a king tide can flood downtown. Combine a full moon, high tide, and the winds/water of a storm event and you can expect serious coastal flooding and damage to occur. And if you combine these commonplace conditions with expected sea level rise forecasts for New England, you better know how to swim. In January, the 15.16ft high tide broke the 1978 record during the first nor’easter.  Then, in the beginning of March, the high tide measured at 14.67ft - its third highest mark in the history of the city. Since 1670, 5000 acres (roughly 200 hectares) of man-made landfill have tripled the size of Boston, but most of it lies just above the current sea level.

In addition to the perilous freezing water conditions and flooding, Boston coastal and island communities lost power in the middle of the storm. Around 442,000 residents in Massachusetts were without power through the three-tide cycle storm. With no means of regaining electricity or connecting to backups, most people had to evacuate from the coast.

How about, connecting the archipelagos of Boston Harbor with a multi-infrastructural, recreational , and ecological sea wall with the landfill from constructing an outer ring of wind turbines and attenuator wave energy devices. On day one, it will mitigate flooding damage to coastal communities and historic downtown Boston. It will provide new open spaces and access to the water while reaching the ocean depth needed for a deep water harbor for the newest classes of shipping vessels.

Day one benefits

  • No more flooding (from the ocean)!

  • Immediately accessible open space and access to the water, swimming, kayaking, boating

  • Newly created connections to national parks and monuments

  • Potential of making Boston the premier port in all of the US East Coast

  • Local and renewable energy production with direct links to coastal communities

  • New habitats and ecology, links to Emerald Necklace and Charles Eliot’s metropolitan park system

  • New destination and tourism driver


Neil Goring
John Frey
Camilla Julie Hvid
Jeremy Anterola
Dimitra Theochari
Andreas Jønck Faartoft
Ryan Michael Shubin

Ramboll & Ramboll Studio Dreiseitl