Integrating visitor reviews and nature-based solutions to explore geoconservation on urban beaches with erosive trends. Case Study of Martianez Beach (Tenerife, Canary Islands)

Abstract

Coastal urban development significantly impacts natural processes, causing ecosystem loss, erosion and flooding. For this reason there is an increasing need for studies that integrate solutions based on the nature of agreement and social perception, especially that of the users of the environment. The aims of the present work are to understand the historical evolution of the beach, analyze its current conditions, and offer applicable management proposals to balance tourism demands with geoconservation principles for sustainable coastal management. In this sense the Martianez beach in Tenerife (Canary Islands, Spain) exemplifies these challenges, as the beach has faced continuous transformations over several decades due to urbanization and management interventions. The methodology of this research included granulometric analyses of sediment collected between 2023 and 2024, a review of historical sources, aerial photographs and orthophotos, a wave dynamics study, and use of a digital shoreline analysis system. Additionally, visitors' reviews on Google Maps were analyzed. The historical evolution of Martianez beach revealed significant transformations over time. Sedimentological patterns are not homogeneous on the beach, with significant differences detected that could be related to beach transformations or beach regeneration. The digital shoreline analysis system (DSAS) showed significant variability in shoreline changes. High shoreline change envelope (SCE) values (10.34 m to 32.41 m) indicate regions of substantial erosion or accretion. Negative net shoreline movement (NSM) values (-23.73 m to-5.75 m) reflect a general trend of shoreline retreat. The range of end point rate (EPR) values (-18.45 m to-0.64 m per year) shows that the southern sector is experiencing more rapid erosion than the northern sector. Based on visitors' reviews, it was found that while the beach offers a scenic and natural landscape and convenient amenities, positive aspects such as its black sand and excellent surfing conditions are counterbalanced by significant drawbacks highlighted in negative reviews. Concerns regarding safety due to rocky outcrops, strong currents, and inadequate rental amenities detract from the overall appeal of the beach. This research could contribute to the development of effective governance tools for sustainable climate change adaptation decisions.