The Houston–Galveston region is one of the most economically important coastal areas in the United States but is highly vulnerable to hurricane-induced storm surges. To reduce flood risk, the U.S. Army Corps of Engineers (USACE) has proposed a storm surge barrier across Bolivar Roads, the primary tidal inlet connecting Galveston Bay to the Gulf. The current reference design includes three permanent barrier islands that reduce the available flow area by approximately 30%, potentially affecting tidal exchange and navigation under normal operating conditions.

This study investigates how the hydraulic and navigational impacts of these barrier islands can be minimised through conceptual design optimisation. An analytical modelling framework was developed to evaluate alternative barrier configurations by representing the hydraulic resistance of the barrier as a function of island geometry, surface roughness, obstruction, and barrier location. The model was used to assess the sensitivity of key design parameters and identify the dominant factors governing tidal exchange.

The analyses show that inlet obstruction is the primary parameter controlling the hydraulic impact of the barrier, whereas detailed island nose and tail geometries have only a minor influence. The USACE reference configuration reduces the tidal amplitude from 31 cm to 24 cm, corresponding to a 22% reduction relative to the existing inlet and exceeding the adopted design objective of limiting tidal amplitude changes to approximately 10%.

Guided by these findings, successive design modifications were applied to reduce hydraulic resistance while maintaining navigational functionality and flood protection performance. The resulting optimised concept combines a single shortened permanent barrier island with convex geometry, vertical concrete walls, and an alternative barrier location. This configuration increases the tidal amplitude from 31 cm to 32 cm relative to the calibrated existing inlet, corresponding to a negligible increase of approximately 1%, while simultaneously improving navigational conditions through a wider navigation opening, larger vessel clearances, and improved channel alignment.

The results demonstrate that a storm surge barrier requiring permanent support islands can be hydraulically feasible at Bolivar Roads, provided that island obstruction is explicitly minimised during conceptual design. The developed analytical framework offers an efficient tool for evaluating alternative barrier concepts before more computationally intensive numerical modelling or physical scale experiments are undertaken.
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Since 2011, large amounts of seaweed, sargassum, have increasingly impacted the Caribbean, with 2025 having another record influx. The resulting sargassum inundation events cause severe ecological degradation, public health concerns and economic losses for coastal communities that rely heavily on tourism, like the area of Quintana Roo in Mexico.
The existing nearshore barriers often fail to intercept most of the sargassum due to poor coordination, unsuitable anchoring, poor design or excessive sargassum accumulation in “sacrificial zones.” If sargassum is allowed to stay still for more than 36 hours, it decomposes, releasing toxic gases, heavy metals and arsenic. The sacrificial zones are a problem area that all current onshore solutions share. To address this issue, this study features the design of a floating nearshore system that transforms these sacrificial zones into “opportunity zones”. It enables efficient interception and guidance, concentration, and extraction of sargassum before it reaches the shore. To attain the goal of the design, a multidisciplinary approach was applied; combining environmental and stakeholder analyses,the system design of a barrier with a collection point, and hydrodynamic simulations in Delft3D to optimize barrier orientation and performance. Different design concepts were developed and evaluated based on technical, operational, and environmental criteria. The resulting concept of the system features a modular floating barrier that guides sargassum towards a designated collection point, the opportunity zone, for extraction. This barrier is supported
by a buoyancy-stable floater, flexible mesh skirt, innovative connections and mooring system. The hydrodynamic analysis confirmed that the orientation of the barrier compared to the barrier significantly affects the flow efficiency of sargassum along the barrier. Through the hydrodynamic analysis, an optimal barrier angle was found to maximize redirection and minimize the length of the barrier. The collection point proposes a solution to collect clean sargassum, whilst minimizing the impact on the environment. This study shows that integrating civil engineering, design thinking, and local knowledge can yield a sustainable near-shore solution. It has to be noted that there are aspects of the design that need further consideration and detailing. This study forms a foundation for scalable sargassum
management. ... Read more