Monday, July 18, 2016

Sunlight Beach

Most of the sand that erodes from the spectacular bluffs south of Maxwelton (March 2010) works its way north past Mackie Park (previous post), then years or decades later, it arrives at the head of Useless Bay, where it spends time on the large spit at Sunlight Beach, before ending up in bars at the mouth of Deer Lagoon.


Sunlight Beach is a long, complicated story. And perhaps one that regularly repeats itself. Sediment for Sunlight Beach comes from the south, but the supply of this material (mainly sand) appears to be metered by a smaller spit just to the south (often referred to locally as Henny's Spit). This southern spit gradually grows, forming a small lagoon and gradually pressing its outlet into Sunlight Beach, which causes erosion and consternation -- in part because the spit berm is the location of the dike that was built a hundred years ago to keep salt water from flooding into the old marsh behind the spit and in part because since then, a large number of people have built their waterfront homes on that same berm/dike.

When the small spit is building, it may starve Sunlight Beach of sand and the beach narrows - thus a diverse assortment of bulkheads, rock revetments, and timber groins. These were visible in the early 1970s and again in the mid-1990s. And are reappearing again.

But if the small spit breaks up, for example, if a new channel opens up farther south, the remaining portion of the spit welds itself onto Sunlight Beach, creating a decade of wide beaches for the residents. Folks who moved in five years ago may not even know that they have riprap and groins down below that wonderful beach,

But then this plug of sediment moves on through, its leading edge moving towards Deer Lagoon and its trailing edge leaving rapid erosion and re-exposed structures farther east. That's what's been happening the last few years.

This is probably a difficult story to follow - it would benefit from a more systematic narrative and a lot of historic maps and pictures. Meanwhile, check out the historic images if you have Google Earth.

I was involved in a number of shoreline issues on Sunlight Beach in the 1990s. For me, early in my beach career, this place was a great case study in the complex dynamics of beaches and spits. It was also clear that while some problems might fade for a few years, most would eventually come back!

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