Tsunami Raises Questions About Seawalls
Earthquakes and resulting tsunamis are known for their immense power and the destruction they leave behind. The mere mention of a tsunami is enough to cause many people to recall the tragic events which took place in Indonesia, Japan, and the horror acts of nature brought fourth during the earthquake and subsequent tsunami. Although the devastation is incredible and the loss of life terrible, some researchers are wondering if tsunamis leave a positive ecological impact in their wake.
According to a new study published in PloS ONE, they just might. Researchers studying the beaches of south central Chile found that the 2010 8.8 magnitude earthquake and the resulting tsunami actually restored sandy beaches. These sandy beaches were mostly gone due to coastal armoring (construction of seawalls, etc.) and together with them various species which thrive on sandy beach habitat. The 2010 tsunami not only restored lost Chilean sandy beaches, but made a way for species to move back to a once lost habitats.
Researchers from the Universidad Austral de Chile as well as UC Santa Barbara’s Marine Science Institute did not set out to document the effects of tsunami on these beaches. The team was originally studying how sandy beaches are affected by man made coastal armors such as seawalls. In a Science Daily report, lead author Eduardo Jaramillo states that seawalls decrease beach area among other draw backs. Dry and damp zones in sandy beaches are also lost because of seawalls, and with them part of beach diversity is lost. Just how much they affect and change the beach area and intertidal diversity is what the team set out to study.
In February, when the tsunami struck, researchers utilized the opportunity to document the after effects of the tsunami on the sandy beaches. They found that the immense sea wave drowned beaches already made vulnerable by subsidence caused by the earthquake. The seawall is also believed to be the factor which widened and flattened beaches uplifted by the earthquake. These beaches were among those which saw a quick return of diversity previously affected by the seawalls, and researchers expect to see the restored inter-tidal zones in the uplifted areas to thrive and retain ecological function.
This study is an important step in considering not only the effectiveness of coastal armors but also their effect on beach habitats. In 2011 one of Japan’s strongest sea walls was shattered by the tsunami. Dubbed the “Great Wall of China” for being the tallest and longest inJapan, the tsunami broke through the seawall in a matter of a few minutes partly due to the coast of Japan actually sinking during the quake.
The seawall protecting the Fukushima nuclear plant also failed to stop the massive waves, breaking into several huge pieces after the tsunami hit. The tsunami eventually struck the reactors and the plant’s cooling systems, resulting in the reactors’ meltdown.
The sea walls’ failure raises the question of whether we really need to build stronger, taller, thicker sea walls. Perhaps resources should be allocated toward evacuation rather than building massive seawalls. Their effects on beaches and the species dependent on these habitats are often overlooked because of the sense of security the coastal armors give. The tsunamis that struck Chile, Japan, and other parts of the world, not only broke through the seawalls but also in some cases restored what was lost due to the seawalls construction in the first place.
An anti-tsunami infrastructure that is both effective and beach habitat-friendly would be great, but easy answers like this are hard to find. To maintain a balance between providing protection for humans while taking care of the environment, a different mindset is needed in approaching the problem.
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