Project Summary

Thatchbed Island is a tidal marsh feature in the lower Connecticut River at Essex that has experienced sustained erosion over recent decades, with the most rapid losses concentrated at the marsh’s southeastern spit. This report includes the results of the investigation into erosion around Thatchbed Island in Essex, Connecticut.

Products

Thatchbed Island Erosion and Mitigation Options Study, An investigation into erosion and potential interventions around Thatchbed Island in Essex, CT

Thatchbed Island Project Final Public Meeting January 14, 2026

Project Description

The project combines shoreline-change analysis (1991–2023), two seasons of in-situ current and sediment measurements, and a high-resolution Delft3D sediment transport model to test how different protective layouts could reduce erosion and promote accretion. We compared geotextile tubes adaptation alternative concepts by representing their hydraulic effect (crest height, footprint, flow reduction) in the model. Results show that a continuous, shore-parallel barrier at the island’s southeast tail can meaningfully reduce bed shear stress and encourage sediment retention on the backfill platform. Site visits and practitioner interviews inform durability, construction logistics, and operations & maintenance needs (e.g., signage, seasonal inspection, repairs). The final recommendations emphasize a phased pilot, clear crest control, sand backfill, toe protection/scour pad, and an maintenance plan while keeping material choice flexible  based on cost, access, and long-term performance.

UConn CIRCA Project Team

James O’Donnell – Executive Director and Prof. Marine Sciences
Yaprak Onat – Associate Director of Research
Marc De Vos – Research Associate
Alejandro Cifuentes-Lorenzen – Associate Research Scientist
Kay Howard-Strobel – Research Associate
Carson Hill – Oceanographic Research Assistant
Nathan Robinson – Research Assistant