JUL 26, 2017 6:53 PM PDT

What are the environmental impacts of sea walls?

Sea levels are rising and as a consequence so are the number of sea walls. However, until now the environmental impacts of sea walls and other engineering “armoring” have been inadequately studied. A team of scientists from UC Santa Barbara and the National Science Foundation's Long-Term Ecological Research (LTER) network recently collaborated to publish a study in the journal Estuaries and Coasts that analyzes a broad range of environmental effects from shoreline armoring in soft marine sediments, shedding light how such infrastructure is changing more than just landscapes.

West End Seawall in Vancouver. Photo: Tourism Vancouver.

"This is one of the first attempts to assess how engineering structures on beaches and other sedimentary environments affect the biota that inhabits these locations," said David Garrison, an LTER program director at the National Science Foundation. "What was novel about this cross-site collaboration was putting these site-specific studies into perspective by making comparisons across a broad range of habitats," said co-author Merryl Alber.

The study looked at results from 88 previous studies that analyzed different types of armoring in diverse soft sediment ecosystems in order to develop a unique conceptual model. "Our model uses two simple axes: the environmental setting of the armoring structure in terms of hydrodynamic energy, like wave and tide regimes, and the degree to which a structure was built to slow water movement or actually stop it from getting through," lead author Jenny Dugan said.

Most of the cases from the existing literature had been in low-energy environments such as salt marshes, tidal creeks, and mangroves. About one-quarter of the cases were from medium-energy systems like harbors, river mouths, and estuaries; only 15% were from high-energy environments such as open coast sandy beaches. Dugan points out that sea level rise means that shoreline armoring structures will experience greater hydrodynamic energy, regardless the type of setting the structure is in.

This sea wall is being constructed to protect a fishing village from flooding in Sundarbans, Bangladesh. Photo: Alamy

While past studies had focused on examining how sea walls and armoring affect changes in habitat and species distribution, this model also takes into account nutrient cycling, connectivity, productivity and trophic structure. The team found that shoreline armoring negatively effects every single one of these categories.

The study explains more in depth, writing that they found “a higher frequency of negative responses for structures designed to stop water flow within a given hydrodynamic energy level. Comparisons across the hydrodynamic energy axis were less clear-cut, but negative responses prevailed (>78%) in high-energy environments. Across the 207 armoring effects studied, 71% were significantly negative, 22% were significantly positive, and 7% reported no significant difference.”

From this study stems the hope that the team’s results will advise engineers how to better take the environment into consideration when constructing soft-sediment shoreline armoring. Dugan says that their results aim to encourage developers to incorporate the ecological costs into the monetary value of projects based on differences in environmental settings and hydrodynamic energy. To see a video of one example of how to build a sea wall, watch the footage below. 

Sources: Estuaries and Coasts, Science Daily

About the Author
  • Kathryn is a curious world-traveller interested in the intersection between nature, culture, history, and people. She has worked for environmental education non-profits and is a Spanish/English interpreter.
You May Also Like
AUG 11, 2021
Space & Astronomy
Researchers Solve Jupiters 'Energy Crisis'
AUG 11, 2021
Researchers Solve Jupiters 'Energy Crisis'
Astronomers have solved Jupiter's 'Energy Crisis', a long-standing issue that has puzzled scientists for dec ...
AUG 12, 2021
Plants & Animals
Why Sunflower Heads Face East
AUG 12, 2021
Why Sunflower Heads Face East
You may have noticed that sunflowers can move their 'heads' or capitula to track the sun as its position changes during ...
AUG 21, 2021
Earth & The Environment
Celebrate Honeybees and Beekeepers on National Honeybee Day!
AUG 21, 2021
Celebrate Honeybees and Beekeepers on National Honeybee Day!
The third Saturday in August, this year the 21st, is National Honeybee Day! The date celebrates honeybee keepers and all ...
SEP 08, 2021
Plants & Animals
Are the skeletons of macaque hybrids distinct?
SEP 08, 2021
Are the skeletons of macaque hybrids distinct?
New research sheds insight into the evolution of the human pelvis by using macaque hybrid models.
SEP 16, 2021
Plants & Animals
Climate Change Is Already Bad for Corn Production. Weeds Make It Worse.
SEP 16, 2021
Climate Change Is Already Bad for Corn Production. Weeds Make It Worse.
Climate change is accelerating, causing more severe droughts, heat, and flooding. The United Nations Intergovernmental P ...
OCT 13, 2021
Earth & The Environment
Fighting Back Against Harmful Algal Blooms
OCT 13, 2021
Fighting Back Against Harmful Algal Blooms
Harmful algal blooms, or HABs, are a common summertime nuisance for people that live near fresh or saltwater all over th ...
Loading Comments...