As sea levels rise, our defense against flood damage may not work as planned -
protecting US coasts from the effects of climate change is costly. But new research shows that using seawalls to protect land can cause tides elsewhere. p>
Changing the Sea
With sea levels rising around the world, humans are forced to build structures to protect themselves — and in the case of the United States, which has 350,000 buildings, they are close to shore. But it can have devastating effects on places we don't choose to protect. Robert Griffin, assistant professor at the University of Massachusetts' Dartmouth School of Marine Science and Technology, decided to look at what happens to the unprotected. Regions. Griffin and his team used hydrodynamic and economic models to investigate flood damage in San Francisco Bay under different scenarios—for example, in different parts of the coast protected by walls of different lengths. (For the experiment, the sea walls are designed with unlimited length). Instead of storms, the team focused on tidal problems and broke down the results based on the amount of sea. Level increase: 50cm, 100cm, 150cm and 200cm above the 2010 level. “This study 'could be useful in different results over time',” Griffin told Aris, adding that the 200cm scenario is nearing the end of current projections for 2100.Advertising
"Displacement effects are related to the morphology of the Earth. Low-lying areas and valleys are likely to contain more water in a flood scenario. If you close those places off in the event of a flood, that water will go somewhere else. If those other places were, Griffin said. It also doesn't defend likewise, so it can increase the damage to those places.
For example, if you protect the Napa-Sonoma Coast, Santa Clara Valley, and San Leandro in the south, the bay could expect $82 million and $70 million in flood damage, respectively. Sea level rise will be 200 cm. San Rafael will also suffer an additional $53 million in flood damage. On the plus side, protecting southern bay areas can reduce minor but extensive damage. For example, protecting the Alamda could reduce flood damage in areas to its south, including San Lorenzo and Newark. This article can also reduce damage on the other side of the coast, near Palo Alto and Silicon Valley.
Although the modeling in this study focuses on the San Francisco Bay, Griffin noted that other parts of the world's coast could see similar effects. In addition, according to the article, about 468 million people live near bays and estuaries. Given that seawalls are already on many beaches, this now-displaced damage may occur - albeit to a lesser degree than if sea level reached worse.
Not all beaches are created equal h2>
The economic damage of floods—whether or not affected by a distant tidal wall—will vary from place to place. In the Bay Area, for example, Napa is relatively sparsely populated compared to Auckland and other urban areas. "However, this area is still more densely populated compared to other parts of the United States," Griffin said.
Theoretically, flood waters can be diverted into ideal areas by using seawalls. This article suggests that strategic flooding of certain parts of the coast, such as steep areas with sufficient area to accommodate water flow, can be used to reduce damage elsewhere. According to this research, there are other considerations when deciding to protect parts of the coast. These include the protection of populations at risk, places of historical interest, places of agricultural importance, etc. Griffin said he hopes the different jurisdictions — cities and states — will start working together to explore potential impacts. of their efforts to protect their shores.
“Planning on a small scale and doing so without looking at its effects elsewhere can lead to unintended consequences that we are only now receiving a measure or value.” “These unintended consequences,” he said. "These findings are not a surprise to Jeremy Porter, director of research and development at First Street, as other efforts to reduce harm from the changes," he said. Weather is often linked to specific issues, for example, in On the Miami coast, the city has raised roads to keep floodwaters away — but the water only flows into other areas, Porter told Aris.“Always that difference, that kind of tension,” he said. “Adaptation – adding the physical infrastructure to manage this type of flood – and the unintended consequences that occur.” "The water has to go somewhere."
Porter agreed that planning to divert floodwaters to strategic locations is a good idea. In addition, he indicated that there may be no cooperation between the various jurisdictions at this time. Large-scale climate adaptation projects are currently funded by the federal or local government. In any case, there is not much incentive for the local government to think about the effects of other areas.
According to Porter, people have long been away from buildings in flood-prone areas - and that was before the current weather. The Outer Banks Islands of North Carolina, for example, were relatively underdeveloped. The barrier islands are now a popular tourist destination, and they and their infrastructure are threatened by flooding. Going forward, buildings probably shouldn't be built in areas that see this amount of water.
"Many of the unintended consequences that happen are because people haven't looked hard enough to see that the weather will be like the next 30, 40, 50 years." Porter said.
PNAS, 2021. DOI: 10.1073/pnas.2025961118. (About DOIs)
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