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As Coastal Populations Grow, So Do Hurricane Risks

Populations along the coasts are growing exponentially, which could mean problems when it comes to hurricane season.

According to 2012 United States Census Bureau data, the nine states with the highest population density are all located along the East Coast. NOAA's State of the Coast research indicates that coastal populations will continue to grow at a faster rate than the rest of the country, with an expected increase of 37 people per square mile for shoreline counties and only an 11 person per square mile increase for the United States as a whole. From 1970 until 2010, coastal populations have risen by 39 percent.

Part of what draws people to coastal cities is rooted in history. When the country was forming, cities were built closer to shores for easy access to shipping routes. Over time, a cycle was created: with more people on the coasts, more development was needed and more jobs were created, which led to more people moving to coasts to get those jobs, which led to further development. As a result, some of the country's biggest centers for trade and industry are located in densely populated East Coast cities. New York City has a population of 8,336,697, with 27,543.1 people per square mile.

Some residents are also drawn to coasts for leisure aspects, such as vacationers purchasing summer homes on beaches or water enthusiasts building their permanent residencies in shoreline communities.

The numbers of people are expanding, but the size of the land is not, and the imbalance wears on resources. Aquatic wildlife populations are affected as building and expansion disrupt their natural habitats. Air pollution increases as more traffic is brought to a more concentrated area. The shores themselves face higher rates of erosion.

While some erosion occurs naturally, waves often slowly replace the sands, they initially pulled away. However, when erosion occurs at an accelerated rate as it does in highly populated areas, the rate of natural replacement is not enough to keep up.

Beach erosion increases the risks when hurricanes hit. Beach elevations are lowered, making them more prone to flooding. Dune erosion diminishes the protective barrier that dunes offer coastal homes, which makes them more susceptible to higher damages. Then, when a strong storm does come through, it erodes beaches even further, making the towns and cities even more vulnerable to future weather effects.

To combat the issue, many coastal governments are implementing building regulations. Permits may be required that demand a reinforcing structure is created before building near beaches. The most common of these are seawalls, walls built out of stone or concrete to hold back bluffs or sand dunes from waves, and groins, which are similar to jetties, but serve a different purpose. Groins are set up to try to "trap" sand that is being pulled by the ocean.

There are problems with these solutions, however. Seawalls protect the land behind them, but increase erosion to the parts of the beach that lay before them. Waters hit the wall and are sent back at a more rapid rate than if they were to creep up the beach then roll away. Groins, when properly constructed, may help to an extent, but they cannot hold all sediment in place.

Another way to prevent accelerated erosion is to decrease beach and water pollution. Coral reefs are natural protectors against rapid erosion, but they are delicate and extremely sensitive to changes in water acidity and temperature. By maintaining the natural state of the ocean, coral reefs remain healthy and alive to control the levels of sand that are washed away.