Urban shorelines are markers of the contested site between the city and the sea. For centuries, coastal cities have expanded their influence further into the sea in the form of land reclamation (also termed “ocean sprawl”), which is responsible for habitat loss, decrease in biodiversity and water pollution. The sea has increasingly become a backdrop to support the growth of business-as-usual (B-A-U) urban developments that are not conducive to the changing climate nor capable of moving beyond the exploitative and superficial engagement with the sea that most cities practice today. However, the consequences of climate change are challenging the sprawl, as the sea is pushing back onto coastal cities in the form of sea level rise and frequent storms. The dominant way coastal cities have responded to this encroachment has been defence-driven mechanical handling of water via sea walls and pumps, a symptom of a reactive rather than proactive response in addressing the climate crisis.

     In response, this PhD research develops an initial hypothesis and a critical proposition called “Urban Seascaping” as an alternative way to re-envision urban coastal developments by exploring the potential of marine nature as an active part of the sociocultural cityscape and its future resilience. Nature-based solutions are emerging as a key component in coastal adaptation and mitigation strategies to address climate change. Furthermore, the green transition of coastal cities is becoming paramount in addressing the rapidly approaching IPCC deadlines/Paris Agreement. The benefits of nature-based solutions are myriad, as they lessen not only the impact of storm surges or coastal erosion but also their capacity to capture carbon, produce oxygen, filter water pollutants, and increase biodiversity as habitats, to name a few. Thus, the research asks: How can coastal cities of Denmark integrate the sea and its lifeforms to contribute towards re‐envisioning urban development in light of a sea level rise and frequent storm surges?

     Too often, issues regarding the changing interface between the city and the sea have been the domain of applied science (i.e. coastal engineers) and natural science (i.e. marine biologists/ecologists) with an emphasis on defence and marine restoration. There has been a lack of engagement from the spatial design disciplines, which might offer a transdisciplinary holistic approach to re-envisioning the entanglements between cities and the sea. However, in the past decade, emerging practices such as Blue urbanism, Coastal urbanism and Urban Ecology have gained traction as a framework for coastal urban development. Therefore, to explore further the role of spatial design disciplines in aiding the increasing complexities and the need for the synthesis of transdisciplinary approaches, the second and third sub-research question of this project asks: How can design research methods and practice from the spatial design disciplines of LUDP (landscape architecture, urban design and planning) contribute to responding to the changing spatial boundary between city and sea, human and nonhuman, due to climate change? What ways of thinking and doing (i.e. world views, representational and analytical tools) can help the spatial design disciplines of LUDP address the aforementioned research questions?

     Much of the existing research on how to integrate marine nature-based solutions in coastal cities by the spatial design disciplines has largely focused on eelgrass restoration, salt marsh and meadows. In contrast, very little attention has been paid to seaweed, the potential of which remains understudied in the field. This is a problem because the different species of seaweed have several unique and positive characteristics that may contribute to marine nature-based solutions. Seaweed can provide not only beneficial ecosystem services but also influence human culture, for instance, as local cuisine in the form of a sustainable and healthy form of food or in its many applications in medicine, cosmetics, and bio-material, to name a few. Therefore, this project focuses on seaweed as a representative of marine nature in the context of urban coastal development. With seaweed as the lens to investigate the research questions, the project develops the concept of Urban Seascaping, which invites the idea of “seascaping” with seaweed in coastal urban environments, much like the way we landscape with trees and flowers. Ultimately, the intention of this conceptual proposition is to find alternative ways of reconceptualising the current dualistic relationship between the city and the sea that characterise B-A-U developments.

     Furthermore, the concept of Urban Seascaping has been developed to present a set of guidelines and perspectives that together provide a framework that can aid in assessing and making informed design decisions for waterfront developments. In the project, four main propositions are put forward. The first proposition departs from an emerging approach called “Multispecies Urbanism” by Debra Solomon, which suggests that cities should not be designed only for human occupation but for other (nonhuman) species. In the context of this research, this means extending the design thinking to include marine life (i.e. seaweed) as a design client and as a rightful resident of coastal cities that people need to learn to coexist with. The second proposition involves a more radical approach to coastal development, which suggests inviting the agency of the sea into the cities. This means departing from the current approach to constantly expand further out into the sea in the form of land reclamation and to embrace the rising sea level with the intention of transforming the waterfront areas into a more hybrid and dynamic place. The third proposition emphasises the need to go beyond the current preoccupation with “the edge” in favour of “a zone” when implementing nature-based solutions. This means addressing the interconnected networks of water that expand further into the landscape and out into the seascape, effectively challenging the conventional conception of a site. The last proposition highlights the importance of making visible marine lifeforms that are otherwise imperceptible to the human residents of coastal cities. This proposition addresses the longstanding exclusion of marine lifeforms in urban development and planning and thus seeks to engage in a spatial design approach that can bring them to the foreground and make their presence more known.

     Putting the Urban Seascpaing propositions to the test, the project investigates the case study context of Vejle, a coastal city in Denmark listed under the flood risk zone assigned by the EU Coastal Directives. Due to its location at the bottom of a river valley where it meets the fjord, the city faces increasing issues with rising sea levels and storm surges. Therefore, in 2020, Vejle Municipality placed an open call for a design competition called “Kanten/The Edge”. It invited practitioners from the field of art, architecture, landscape architecture and urban design to redesign two main “edge” conditions between the city and the fjord using innovative nature-based solutions to protect Vejle from future scenarios of sea-level rise and storm surge. Kanten/The Edge competition marked the start of a green transition in the waterfront towards a public space that is accessible, recreational, artistic and adaptative. In short, the competition sought to provoke alternative perspectives and engagements with the water.

     Guided by these four propositions, the dissertation presents an in-depth analysis of the case competition itself – along with its design entries and winners. In this way, the competition is used in the project as a source for design “data” analysis and thereby as a way to provide answers to the research questions mentioned above. The analysis demonstrates that engaging with fluid entities such as water necessitates going beyond the neat boundaries of conventional design sites (i.e. the edge condition). Ultimately, this meant exploring beyond the confines of the site allocated by Kanten/The Edge competition to one considering multiple scales, long-term timeframes and different perspectives. In short, a deep reading of the complex entangled characteristics of the context was needed. To accomplish this, the dissertation develops a multiscalar network mapping tool that can effectively visualise the relationship between the history of urban development and its interconnection to the landscape-seascape continuum. Specifically, three maps were developed, each of which presents a different set of relations across time and space that seek to situate Vejle in various contexts and timeframes, from the microscopic to the global. This act of mapping exemplifies the dissertation’s use of the research-through-design methodology, which offers itself as a helpful tool in formulating possible projections of design solutions in Vejle. Finally, the method of mapping proved to be an apt medium to translate the four propositions of Urban Seascaping into general applicable design principles and parameters through a legible common visual language.

     As a result of the map-driven deep site analysis guided by the Urban Seascaping propositions of the Kanten/The Edge entries, the project reports several findings and suggestions for both the Vejle context and urban coastal development in general. The broadest and most important of these findings is the need for the LUPD disciplines to foreground relationality and transdisciplinary collaboration in their engagement with the urban shoreline. In engaging with the fourth Urban Seascaping proposition of “making the invisible visible”, it became apparent on a micro-scale that seaweed on the waterfront remains imperceptible and difficult to thrive due to the poor water clarity of the fjord, which inhibits the success of marine nature-based solutions. Following the multiscalar network, the map demonstrates a causal relationship between the murky water and the significant amount of floating nutrients discharged from agricultural runoffs, thus illustrating a move from the micro-scale to the watershed scale. In turn, looking at the watershed scale necessitates limiting the sources of water pollution from a landscape perspective by engaging with wetlands next to the watercourse to capture the pollutants as much as possible before they are dispelled into the fjord. While Vejle Municipality is already implementing these wetland restorations, Kanten/The Edge could exemplify this green-to-blue, upstream-to-downstream transition in the waterfront area, tying the water’s network through walking trails and spatial design. The research findings also found that engaging with marine nature-based (with seaweed) requires a much larger scale of engagement to be effective in mitigating the impacts of climate change beyond the confines of an edge condition (i.e. a “blue line”).

     Kanten/The Edge’s winning proposal engaged with the second proposition to invite the agency of the sea by allowing the water to transform the waterfront area into an aquatic terrain. Another winning proposal engaged with the third proposition to go beyond the edge conditions by expanding the nature-based solutions out into the water in reference to the coastal areas lost previously from the land reclamation process. Both proposals demonstrated expanding the conception of an edge to a larger zone by conceiving the larger waterfront area as a buffer zone. Therefore, the landscape approach in the winning entries of Kanten/The Edge demonstrated a long-term plan to gradually transform the waterfront into a new form of blue commons. Here stone reefs, rock pools, and floating platforms would be placed out into the water, and the design of a landscape-to-seascape transition could provide a tactile and visual-spatial experience. This formation of a blue urban commons would open up the current inaccessible harbourfront to the public, providing an opportunity for a much more democratic meeting place between humans and nonhumans, fostering multispecies coexistence (i.e. the first proposition). The winning proposals from Kanten/The Edge integrated art into rethinking the entire waterfront, for instance, by introducing a sculptural house fit for a fish by flipping the perspective upside down. Although Kanten/The Edge is a small precedent in an emerging alternative blue-green transition for coastal cities, the dissertation suggests that the competition has generated several pioneering examples and insights that can lead to imagining better practices.

     Lastly, engaging with long-term scenarios beyond this century showed that with extreme sea level rise and storm surge events, suburbs on top of the river valley in Vejle would be safe, while the current city centre at the waterfront would be completely submerged. This scenario sediments the fact that it no longer makes sense to keep developing B-A-U in the risk zone. Thus, the research suggests opting for a sensible long-term retreat plan that diverts the developments on higher grounds, providing room for more visionary solutions on the waterfront that mutually benefit people and coastal ecosystems. If a meaningful transition to net zero is expected by 2050 (as outlined in the IPCC report), a more radical rethinking of the current boundary between city and sea is needed. This involves conceptualising the site in question as a multiscalar, temporal, hybrid and interconnected zone that can address the challenges of climate change more effectively. Hence, Urban Seascaping serves as a critical proposition to induce transdisciplinary discussions on the value of integrating the forgotten and invisible agency of the marine realm into the visible urban realm for an equitable meeting place between humans and nonhumans. It contributes to the emerging field of blue urbanism and coastal urbanism from the lens of seaweed. That being said, it is not only a story about seaweed, but an ongoing and unfinished story of relations, entanglement, response-ability and extending our understanding beyond our immediate borders. Urban Seascaping with seaweed presents a small yet significant piece of the puzzle in addressing the climate crisis and the role the spatial design disciplines can play in coastal urban development.