Why it's so hard to keep P.E.I. harbours clear of sandbars

Sand is an integral part of P.E.I. It makes the beautiful beaches and magnificent sand dunes, but it can also be dangerous for fishermen.

"P.E.I. has sandbars all around its coast and they're beautiful systems," retired research scientist Don Forbes told CBC's Island Morning.

But because those sandbars often remain underwater they can be a hazard for boats. This spring, they were a particular problem at Hardy's Channel and Covehead.

The deep shelf of sand around the Island's shores can extend for kilometres out into the Gulf of St. Lawrence, and it's easily moved by waves. Waves reach down underwater as far as they rise up above, and when they hit the sandy bottom they create complex currents that move the sand around.

Around inlets, where harbours are typically situated, tidal currents can make the systems even more complicated.

"If there's any wave action you'll see several lines of breakers and those are breaking on the bars. There can be typically two to five bars in the first few hundred metres off the beach," said Forbes.

"Every storm that comes through will change the bars."

Climate change and sandbars

There has been less ice around the Island in recent years, and that makes the problem worse.

Ice will dampen the wave action close to the shore, preventing the formation of sandbars. The longer it takes that shoreline ice to form, the more time there is for fall and winter storms to reshape the underwater landscape.

Because each storm is different, it can be difficult to predict where the sandbars will form.

Apart from dredging, physically removing the sand that has gathered, the only other solution is the creation of structures such as jetties that shift the currents and prevent sandbars from forming.

These are expensive, however, and can lead to unwanted erosion on other parts of the shoreline.

As winters continue to warm, said Forbes, and there is less ice, the problem with sandbars is likely to get worse in coming years.

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