Designing for delivery: the next step of Water as Leverage Cartagena

In the neighbourhoods along the Juan Angola Canal, a downpour is rarely without consequences. Streets can flood within minutes, and the city has spent years trying to bring urban growth back in step with the landscape. With phase 3 of Water as Leverage, this should take shape for the first time, with detailed designs and implementation roadmaps for paving stones, culverts and mangrove restoration. Furthermore, these plans are genuinely bankable and ready to implement.

What is Water as Leverage?

Water as Leverage (WaL) is a Dutch approach that reverses the usual sequence: rather than having a technical plan first and then looking for support and funding, this approach brings together knowledge, governance, financing, and communities from day one. In multidisciplinary teams of Colombian, Dutch, and international experts, early sketches grow into concrete designs ready for further development.

“It’s the integrated perspective – physical system, ecology, economy, employment, and financing – that makes WaL truly unique,” explains Michel Zuijderwijk from Witteveen+Bos. “You’re not only designing for water, but also for the city and its residents.” Witteveen+Bos is the lead partner of the Roots of Cartagena team, which has been working within the Water as Leverage Cartagena programme.

What is the current status of the WaL Cartagena programme?

During phase 1 which started in February 2023, these two teams explored Cartagena’s bottlenecks and opportunities regarding water and climate adaptation. This produced an initial city outlook and a selection of hotspots where water, public space, and quality of life intersect. At the end of this phase, eleven concepts were on the longlist.

During phase 2, beginning at the end of September that year, this was narrowed down to five serious project candidates and technically underpinned to pre-feasibility. Five local design workshops with local stakeholders proved decisive: specific areas of the Juan Angola Canal were given the green light to continue towards a third phase, with nature-based measures and practical interventions that are easy to scale up.

Colombian delegation’s visit to the Netherlands: three lessons

As the kick-off for the third and final phase of this programme, a Colombian delegation visited the Netherlands to look at waterworks, nature-inclusive projects, and maintenance regimes, such as the Sand Engine near Kijkduin (beach nourishment as coastal protection), Benthemplein Water Square in Rotterdam (urban water storage), and the Marker Wadden islands (nature restoration built with dredged sediment). Wilmer Iriarte Restrepo, Cartagena’s Secretary of Infrastructure, named several key insights to take into the next phase:

• Link flood resilience to public space.
  “Look at flood resilience and public space as one entity. Maintenance thus becomes logical and you create pleasant places that residents actually use.”
• Let nature do the work.
  “From ‘sand motor’ to sluices: harness natural processes and the topography to filter and direct water. Not dogmatically, but flexibly: what works here may work differently elsewhere.”
• Keep solutions simple and scale them up.
  “Sometimes the best intervention is to give streets a little more slope and install a narrow gutter in the drainage system. Simple in itself, but if applied a thousand times, the cumulative impact is substantial.”

This down-to-earth view aligns with the WaL method: nature-based solutions where possible, hard interventions where necessary. “NBS are never one-size-fits-all,” says Zuijderwijk. “They are context-specific; that’s precisely why you always design together with the place in question.”

The next phase: feasibility studies for the Juan Angola Canal

One project has been selected within WaL Cartagena to proceed to feasibility studies in phase 3: the Juan Angola Canal. The WaL Project Proposal concerns flood resilience and quality of life, upstream and downstream, and is well aligned with local needs and plans. It roughly entails the following:

• Along Juan Angola, the bank would be gradually transformed into a continuous city park. The canal would be given room to breathe: it would be deepened and restored so that water can flow better. A footpath would connect places to linger and steps down to the water; in quieter sections, reed beds, riparian plants, and shallow sheltered zones will attract fish, birds, and insects. This gives rise to a place where flood protection coincides with a pleasant, green route through the neighbourhood.
• Higher up, on the slopes and in the streets, rainwater would be retained. Infiltration cells, green verges, and small storage areas give water time to percolate into the soil, while at strategic points, culverts lead the surplus to the canal in a controlled way. Replanting bare embankments binds the soil and slows erosion, so that less sand and silt reach the lower city. The result would be a chain of simple interventions that together calm the system and make the neighbourhood more liveable.

“I see a lot of methodological overlap between the WaL design and what the municipality is already doing,” says Iriarte. “From the characterisation of the micro-catchment to the idea of public space with footpaths and viewpoints: we’re on the same page. I also recognize innovative elements from the WaL team – for example, ideas related to biodiversity in the canal; we’d like to replicate those.”

What the Netherlands has learned from the WaL Cartagena programme

Barbara Swart, coordinator of bilateral cooperation on water and climate adaptation at the Dutch Ministry of Infrastructure and Water Management (IenW) and lead within Partners for Water, sees in WaL Cartagena exactly what the Netherlands is aiming for with international cooperation: impact on the ground and learning from each other. “It’s great to provide and to collect knowledge,” says Swart. “But above all, we want to see that this knowledge is used: that Cartagena’s residents benefit directly. WaL is integral and inclusive; it is developed together with the communities. That makes it stronger.”

On an earlier visit to the city, she and her team saw the enormous opportunities here. It’s a coastal city where water and climate challenges, public space, and social development converge. That makes the area eminently suitable for projects that not only reduce flood risks, but also regreen neighbourhoods, improve health and quality of life, and strengthen local ownership. Because the city also prioritises these aspects and financiers have been engaged from day one, this paves the way for tangible results in the short term and a scalable route to larger water infrastructure.

She emphasises that this cooperation is a two-way street. “We’re still ‘Nederland Waterland’, a country reclaimed from the water,” says Swart, “but in other regions, extreme rains, heat and drought have been going on longer and are more severe. We can learn from that. A striking example is the principle that water and soil are considered in spatial decisions. The Netherlands and Colombia embedded this in policy around the same time. Then you want to know how it works in practice. Who achieves results faster, and why?”

Financing: early at the table, but with local ownership

From the start, financiers and development banks have been at the table to test whether a design will be bankable later. Swart: “Here we have an intermediary role: bringing parties to the table and hearing their ideas. But ownership lies in Cartagena. The city must determine whom to partner with and how the link to national budgets will work. We’re not the leading party. (…) The most important thing is to produce concrete, bankable packages which financiers can commit to.” Financing resilient urban projects is usually challenging, due to fiscal restrictions in governments, both local and national, emphasises Zuijderwijk.

Final phase

Meanwhile, work continues apace. “In the short term, the municipality would like to push at least one section of the canal design quickly through the approval process,” says Zuijderwijk. “A challenge, but doable. Immediately after, we would elaborate the longer-term measures: hydrological model, impact calculations, environmental frameworks, and the financing mix.” Phase 3 is being shaped with our partners at the municipality, says Swart. “We want to deliver early results and set out the vision and elaboration for the larger water infrastructure project that can be implemented later.”

Participation as a design decision-maker

Social dialogue will be crucial in the period ahead. Iriarte sees an opportunity here. “In phase 3 we can establish methods and forms of social consultation that allow us to systematically gather residents’ ideas, knowledge, and concerns. Neighbours sometimes disagree – you must keep an eye on that. It could be about something small, like where a bridge should be. But that’s where a good solution begins, by accommodating the different parties.” This ties in with one of the aspects Swart finds so inspiring in Colombia: “Embedding indigenous and local knowledge. We have participation in the Netherlands too, but in Colombia you see how self-evident it is that communities co-decide. It works, and it translates into simpler maintenance and tangible ownership.”

What is ultimately at stake?

For Cartagena: fewer floods, more shade and greenery, better access to water and public space, and less sediment washing into the lower city. For the Netherlands: practical knowledge about scaling up nature-inclusive solutions in a tropical coastal city, about financing climate adaptation projects, and about embedding management in community structures. Regarding global cooperation, there is another ambition. “In 2023 we agreed the Water Action Agenda at the UN Water Conference,” says Swart. “This means we need to take action. We talk a lot, but ultimately, it’s about visible results. Because of the effects of climate change the urgency has grown, and I would love it if we could demonstrate what WaL has delivered in concrete terms at the next conference in 2026. This requires a joint acceleration now. To get there, all partners – Cartagena’s authorities, communities, Dutch and international funders, and the WaL consortium – need to accelerate delivery now.”