Huff, T.P. and Feagin, R.A., 2017. Restoring tidal equilibrium: Removing a hydrologic barrier and lowering salinity at the Magnolia Inlet, Texas. In: Martínez, M.L.; Taramelli, A., and Silva, R. (eds.), Coastal Resilience: Exploring the Many Challenges from Different Viewpoints. Journal of Coastal Research, Special Issue No. 77, pp. 97–103. Coconut Creek (Florida), ISSN 0749-0208.
A large area of salt marsh located between Magnolia Beach and Indianola, Texas had rapidly degraded over the last few decades due to a hydrologic barrier. Sediment and shell debris in the main tidal channel had greatly reduced flow between interior sections of marsh and the adjacent open bay, blocking all hydrologic exchange except for extreme tides. As a result, the impounded waters were often hypersaline, the vegetation was dying, and access to habitat was restricted for aquatic nekton. Our overall objective was to identify the cross section of debris that would need to be removed from the channel in order to restore hydrologic flow. Using numerical modelling, the first goal was to identify the cross-section of the channel that would allow equilibrium with the potential tidal prism of the impounded water basin. Using a STELLA modelling approach, the second goal was to identify the length of time that it would take to restore normal salinity levels. Based on both these models and observed historical trends, a removal option of 13.5 m2 inlet cross-section was selected, such that maximum water velocities (~0.8 m/sec) were predicted to reduce the probability that the channel would revert back to a blocked state and that salinities would equilibrate in less than 12 days. Approximately 780 m3 of shell and mud debris was removed, and field-measurements of both tidal flow and salinity generally verified the modelled predictions. Afterwards, the community began recovering with vegetation colonizing previously flooded areas and fish accessing the marsh as the barrier no longer blocked fish movement.
