222 Delta Evolution from Rivers to the Shelf: Past, Present and Future Perspectives for Society (Posters)

The session focuses on deltas and adjacent depositional environments from fluvial systems to the continental shelf. Research on modern, ancient or extraterrestrial deltas that emphasize their importance to our society is welcome.

Tuesday, 21 October 2025
8:00 AM - 5:30 PM
HBGCC, Hall 1

Multispectral UAV Monitoring of Suspended Sediment Dynamics in Trinity and Matagorda Bays

Paper number: 222-6
Program: Technical Sessions
Time: 8:00 AM – 8:00 AM

Authors

Abstract

Suspended sediments affect water quality, ecosystems, and shoreline stability in coastal systems. Understanding their spatial and temporal variability is essential for effective coastal management. Traditionally, suspended sediments are measured by filtering and weighing solids from water samples, however this provides limited spatiotemporal coverage and is time- and labor-intensive. This project aims to build tools to predict total suspended solids (TSS) using multispectral UAV data from two contrasting Texas bays, Trinity Bay (TB) and Matagorda Bay (MB). Both bays receive direct river input, however MB is more influenced by marine exchange. Between August 2024 and July 2025, twelve monthly multispectral UAV flights were conducted over each bay, paired with in-situ water sampling conducted on the same day to obtain TSS measurements. Red, Green, NIR, and Red-Edge bands were processed into orthomosaics. Open water was isolated using the Normalized Difference Water Index (NDWI), and shoreline vegetation was removed using the Red Edge Simple Ratio (SRre). Three spectral indices, Normalized Difference Turbidity Index (NDTI), Suspended Sediment Index (SSI), and Bounded Turbidity Ratio (BTR), were calculated as reflectance-based proxies for suspended sediment in the upper water column.

In TB, SSI values were highest near the Trinity River mouth in February and March following rainfall events which generated broad sediment plumes. SSI values declined through June, as freshwater input decreased. MB exhibited lower, more uniform SSI values, reflecting limited river input and minimal seasonal variation.

These results show that multispectral indices can aid in detecting surface sediment patterns. UAV-based monitoring provides a high-resolution, cost-effective tool for tracking suspended sediment in coastal systems.

Geological Society of America Abstracts with Programs. Vol. 57, No. 6

doi: 10.1130/abs/2025AM-412892

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