My next effort will be to add a video to the still pictures that are on the blog. This video will feature a novel 19th century feature - the Safety Dam.
The video starts by showing you a stretch of the Rideau River in the village of Manotick near the city of Ottawa , Canada 's capital. This is the East arm of the river as it flows around Long Island . Part of the village of Manotick is situated on this island.
At the north end of the island is an historic dam, one of the largest dams on this UNESCO World Heritage Waterway.
To protect this dam, the associated triple boat locks and the spillway, engineers of the 19th century designed a safety dam. This safety dam is shown in the video. During operation this “dam” is open to the river’s flow and to normal boat and barge navigation. In times of expected severe flood flows, as for example the spring freshet, stop logs were inserted into slots built into the abutments. The flood waters were then re-routed to the back channel on the West side of the island; in effect turning the back channel into a long, natural spillway and thus by-passing the flood flows from the dam, the locks and the spillway structure.
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