The Course of History

The River Sid we see today is the result of thousands of years of geological shifts and centuries of human engineering. Understanding its history helps us grasp why the river behaves the way it does today.

1. Natural Origins: From Ice Age to Misfit Stream

The valley’s shape was largely determined by ancient climate events.

• Pleistocene Meltwaters: The broad, deep valleys of the Sid were likely carved by massive meltwaters during the Pleistocene epoch.

• Misfit Streams: Because the current River Sid is much smaller than the river that originally carved the valley, geographers call it a "misfit stream".

• Bronze Age Changes: Following widespread deforestation in the Bronze Age, there was a significant increase in "colluvium" (hillwash) entering the river system.

2. The Shifting River Mouth

The point where the Sid meets the sea has moved significantly over the centuries due to natural forces.

• The Shingle Ridge: Longshore drift created a shingle ridge that grew eastwards across the estuary, gradually pushing the river's outlet along with it.

• The Great Storm of 1322: A massive storm in 1322 shifted the lower reaches of the river eastwards, roughly along the line of what is now Mill Street and York Street.

• Historical Siltation: The lower reaches originally formed an inlet that eventually silted up behind the shingle ridge, creating the land where the eastern part of Sidmouth town centre stands today.

3. Human-Induced Changes

For centuries, humans have modified the Sid for flood protection, land reclamation, and industry.

• Re-routing the River: In the early 1700s, the river was re-routed into a newly cut straight section, establishing the current course we see today.

• The Ham: This area was historically a marshy floodplain to the east of the channel, but its west bank was straightened and armored to reclaim the land.

• Channel Armoring: Within Sidmouth town, the riverbanks are "highly modified". This includes a 100-year-old training wall at the river outlet and a robust wall near the ford to confine the water.

4. Modern Engineering and Biodiversity

While modern structures protect the town from flooding, they often come at an ecological cost.

• The School Weir: Built in 1974 as part of a flood alleviation scheme, this 2.5m high structure acts as a "waterfall".

• Impact on Fish: This weir is a major barrier that prevents migratory fish, such as salmon and eels, from moving upstream, which reduces the river’s biodiversity.

• Recent Developments: In 1921, the western wall was extended, reducing the bridge at the mouth from three spans to two and creating the triangular hardstanding area seen today.