Measurements of wave runup and groundwater at Ostional beach in context of the TURTLE project

Abstract

Sea turtle nesting beaches are under increasing pressure
from climate change, rising sea levels, and human activity, making the
protection of critical habitats like Ostional Beach, Costa Rica, an urgent
priority. This study integrates the analysis of wave runup dynamics,
groundwater behavior, stakeholder collaboration, and coastal squeeze mitigation
to address the unique challenges at this vital olive ridley turtle nesting
site.

Wave runup was examined using timestack imagery analysis.
Two automated extraction models— entropy-only and entropy-saturation—were
compared against manually digitized data. Results show that the entropy-only
model is more reliable in capturing peak wave run-up values, a critical measure
for understanding inundation risks. Challenges in accuracy, particularly for
the entropy-saturation model, were linked to the site’s unique environmental
conditions, such as dark volcanic sand. The findings fill a gap in understanding
how specific extraction methods perform under unique site conditions, with
implications for improving future modeling efforts.

Groundwater dynamics were studied using pressure sensors
installed in custom-built wells, revealing significant interactions with tidal
forces. These measurements highlighted the role of tidal cycles in influencing
groundwater levels, providing crucial insights into the potential for nest
inundation. These findings extend existing knowledge by combining tidal and
hydrodynamic factors specific to turtle nesting sites.

Collaboration within the TURTLE project was analyzed through
semi-structured interviews and structural evaluation of partner interactions. A
tailored framework was developed to enhance communication and coordination
among stakeholders, addressing identified gaps and leveraging existing
strengths. This framework contributes to more effective project management and
the application of scientific insights in conservation strategies.

To mitigate coastal squeeze—a phenomenon where natural
habitats are compressed by rising sea levels and human development—the study
evaluated strategies such as foreland restoration and managed retreat. Findings
suggest that integrating habitat restoration with community involvement is
critical to preserving the ecological and social balance at Ostional Beach.

This study takes an interdisciplinary approach to explore
how wave runup, groundwater behavior, and collaboration strategies can be
effectively combined to support conservation efforts. The results stress the
need for tailored, site-specific solutions that blend engineering, ecological,
and social perspectives to protect endangered species and their habitats. By
bridging knowledge gaps and offering practical recommendations, the research
bolsters both local and global initiatives aimed at preserving vulnerable
coastal ecosystems.