Quantifying the Impacts of Unpaved Road Sedimentation on Coral Reef Health in Culebra, Puerto Rico

Authors: Preston McLaughlin*, University of Texas - Austin
Topics: Geomorphology, Physical Geography, Coastal and Marine
Keywords: road erosion, Caribbean, Puerto Rico, rainfall simulation, coral reefs, dry tropics
Session Type: Poster
Day: 4/13/2018
Start / End Time: 5:20 PM / 7:00 PM
Room: Napoleon Foyer/Common St. Corridor, Sheraton, 3rd Floor
Presentation File: Download

Terrigenous sedimentation into tropical coastal waters from land development is a key stressor influencing the global decline of coral reef ecosystems, and Caribbean reefs are amongst the most affected. This study focuses on estimating sediment yields for Isla de Culebra in Puerto Rico by quantifying runoff and sediment production from undisturbed hillslopes and unpaved roads using plot-scale rainfall simulations. Culebra houses several endangered species and is one of only four priority coral reef management sites for the Territory. Measured unpaved road segments vary in slope and represent both freshly graded/compacted roadbeds and those on which roadbed maintenance had not occurred for more than a year. The average rainfall application rate was 5.8 cm hr-1. Preliminary results indicate significant discrepancies between runoff rates for unpaved roads and undisturbed areas. Time to runoff for unpaved roads and undisturbed surfaces averaged at 5 min 11 seconds and 2 hrs 25 min, respectively. Runoff coefficients averaged 76.4% and 2.6% for unpaved roads and undisturbed plots, respectively. By comparing the differences in runoff and sediment production between undisturbed and disturbed surfaces, this analysis will allow us to quantify sediment delivery to Culebra’s coastal waters from watersheds with varying degrees of land development. The information derived from this research can help influence decisions that focus on coral reef preservation and effective unpaved road management throughout the US Caribbean.

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