Thesis Defense Seminar - Isabel Nykamp

COASTAL AND MARINE SYSTEM SCIENCE PROGRAM

DEPARTMENT OF PHYSICAL AND ENVIRONMENTAL SCIENCES

TEXAS A&M UNIVERSITY-CORPUS CHRISTI

SUBJECT:  ADVANCING METHODS FOR DAMAGE DETECTION & RESTORATION ON WIND-TIDAL FLATS IN SOUTH TEXAS

COMMITTEE:   Dr. Jennifer Beseres Pollack (Chair), Dr. Michael Starek, Dr. Kim Withers, Dr. James Gibeaut

ABSTRACT

Wind-tidal flats are dominant wetlands across the south Texas coast, characterized by extreme physical conditions that support laminated cyanobacteria mats, benthic infauna, and migratory shorebirds. These systems provide essential ecosystem services such as sediment stabilization, nutrient cycling, and storm attenuation, yet are widely degraded by vehicle rutting and other disturbances. Despite their ecological importance, wind-tidal flats remain poorly understood, with no standardized methods for assessing damage or guiding restoration.

This thesis addresses these gaps through two complementary studies. First, high-resolution digital surface models (DSMs) generated from uncrewed aircraft systems (UAS) were used to detect and quantify rutting damage at two sites. Surface depressions were identified from a difference raster generated by subtracting a smoothed DSM from the original; subsequent classification accuracy was assessed using confusion matrices. Accuracy ranged from 60-70%, with sensitivity and specificity varying by site and method. Historical aerial imagery (2004, 2014) was used to assess damage persistence, revealing that ruts can persist for decades, especially in areas with limited new disturbance, indicating minimal passive recovery.

Second, field experiments tested three in situ elevation restoration treatments (burlap, psyllium, and sand) at two degraded wind-tidal flat sites. Plots were monitored for one year. During quarterly sampling events elevation recovery, cyanobacterial mat development, inundation, and sediment characteristics were monitored. Burlap treatments consistently maintained surface elevation and supported more rapid mat colonization compared to other methods. Restoration outcomes varied by inundation regime, site conditions, and sediment composition.

These studies demonstrate that UAS-based elevation models provide a scalable approach to monitor surface damage, and that targeted interventions can accelerate recovery in low-relief, biologically sensitive systems. This work provides a foundation for future restoration planning, monitoring, and management of wind-tidal flats in arid coastal environments.