Yes, very hard on the boat owners. Those boats that upended will be a real mess inside.
When you look at the photos you can see that an embankment was built into the side of the hill and the top of has the shallow canal let into it. Some reports say that there was a drainage culvert under the canal, probably constructed from brick, and this may have collapsed, destabilising the embankment and spilling water across the nearby fields. The water flow would have made the initial breach much larger.
It seems a logical explanation.
Colin
