The elusive intertidal: Wave forms and coastal dynamics through architectural representation

Background This study combines cartographic sources with the situated knowledge of the local surfing community to address the lack of information describing intertidal zones in coastal areas, using the mouth of the Douro River as a case study. It employs architectural representation as a means of integrating knowledge from different disciplines and exploring the relationships among wave action, currents, flooding, and shoreline evolution. The underlying hypothesis is that recurring coastal and seabed configurations reflect recurring maritime dynamics, and that the ways in which these dynamics are represented contribute to the social construction of facts. Methods The methodology involved the systematic archival collection of 75 documents (1634–2021), which were standardised to reveal long-term transformations of the sandspit. These historical records were compared with oral histories and personal archives from surfers who experienced the river mouth before the construction of the jetties. These disparate sources were integrated into original drawings using architectural conventions to represent dynamic processes within a static medium. Results Using the mouth of the Douro River in Porto, Portugal, as a case study, this research maps dynamic coastal systems and identifies the tensions between biophysical morphogenesis and competing human uses, such as port navigation and surfing. It identifies changing patterns within the intertidal zone through historical cartographic evidence, reconstructs vanished wave forms through surfers’ counternarratives, and employs architectural representation to bridge the gap between terrestrial and marine modes of representation. Conclusion By applying critical cartography and the concept of situated knowledges , this study challenges the “view from nowhere” associated with conventional mapping. It demonstrates how the 2004 construction of the jetties privileged engineering interests over the situated expertise of surfers, whose world-class waves were erased from the official record. Ultimately, the paper reframes the intertidal as a site of “matters of concern,” where biophysical and social agencies converge.