Barcelona is often celebrated for its innovative approach to urban planning, but how does this translate into practice? As part of our exploration of nature-based solutions (NbS) and green infrastructure (GI), our master’s had the opportunity to visit several key sites and learn from Gabino Carballo, a seasoned landscape architect and NbS project coordinator at Natural Base Solutions. The visit allowed us to critically analyze the implementation of NbS at the municipal level, assessing both their successes and shortcomings. Through this, we deepened our understanding of urban resilience and the real-world challenges of maintaining sustainable landscapes in a dense metropolitan setting.
Key Takeaways: Green Infrastructure and NbS in Action
One of the primary insights from the visit was the evolving nature of green infrastructure in Barcelona. The city’s urban landscape is shaped by the contrast between Ildefons Cerdà’s original plan and the realities of modern urbanization. Over the years, various policies have sought to integrate green infrastructure, culminating in the Pla del Verd i de la Biodiversitat de Barcelona 2020 and the Pla Natura Barcelona 2021-2030.
A major revelation was the distinction between natural and engineered NbS. While the term “Nature-Based Solutions” suggests working with nature, much of what we observed was highly engineered. Bioengineering techniques that manipulate natural processes to create sustainable outcomes. For example, Sustainable Urban Drainage Systems (SUDS), a form of Low Impact Development (LID), mimic natural water cycles through infiltration and evapotranspiration, reducing runoff and improving water quality.
Challenges and Observations
While the site visits showcased impressive NbS initiatives, they also revealed key challenges in implementation and maintenance. One notable example was an unmaintained NbS implementation using horizontal tree trunks, also known as log erosion barriers, for erosion control on slopes. These barriers were designed to create various plateaus throughout the slope, allowing for better water penetration into the sediment. However, due to the lack of upkeep, some of these structures had deteriorated, reducing their effectiveness and leading to increased erosion. This highlights the need for sustained investment and adaptive management in NbS projects.
We saw real-world implementations of Barcelona’s master plan and how they are or are not maintained over time. One key observation was the use of organic and synthetic nettings for slope stabilization, combining coco coir and polyester fiber with a metal top net. This design facilitated vegetation growth, which further stabilized the sediment. However, this intervention was not in its best condition and suffered from under maintenance, reducing its long-term effectiveness.
Another notable feature was the biodiversity node, a designated area with restricted access to minimize human disturbance and promote ecological balance. This space included an open water storage system, which served as a crucial resource for small animals, allowing them to drink and clean themselves. Such features demonstrate how NbS can support urban biodiversity by integrating habitat-friendly elements, provided they receive adequate maintenance to remain functional over time.
Connection to Theory: Urban Resilience in Practice
While many green infrastructure ideas are promising in theory, our visit highlighted the critical gap between conceptual planning and practical implementation. One of the biggest challenges cities face is the long-term maintenance of NbS. While GI is often relatively inexpensive to create, its benefits such as stormwater retention, biodiversity enhancement, and urban cooling can only be sustained if proper upkeep is ensured. Without ongoing management, infrastructure designed to provide resilience can instead become a source of new vulnerabilities, as seen with unmaintained erosion control measures and clogged water management systems.
This visit underscored the need for a paradigm shift where cities prioritize not just the initial implementation of green solutions but also their continuous management and adaptation. Without a commitment to maintenance, the effectiveness of these systems diminishes over time, undermining their role in climate adaptation and urban resilience.
Reflections on Urban Resilience
This site visit provided a crucial opportunity to move beyond theory and assess how urban resilience measures are being realized on the ground. While Barcelona has made significant strides in integrating green infrastructure and NbS, the challenges of maintenance, accessibility, and social equity remain pressing concerns.
The experience reinforced the idea that urban resilience is not just about creating green spaces but about continuously managing and improving them. Cities must balance between ecological restoration and social inclusivity, ensuring that resilience efforts benefit all residents.