Erosion of the River Bank in Kilcullen

Crop of a Lawrence Collection photo of the River Liffey in Kilcullen. Image courtesy the National Library of Ireland.

A close-up crop from a Lawrence Collection photo, circa 1900, showing a section of the river bank that had slipped into the river near what's now the entrance through the bushes onto the mass path. It's probably taken from the vantage point of the bridge or the slope where the Valley Park is now located. The slippage could have occurred decades or hundreds of years before. Interestingly, as far as I remember it, there was a ditch just before the fence in the photo (not sure whether it was the same fence in the 70s), which we used to have to step over to walk further along the path. I noticed recently, from hearing water running, that the ditch, if it's the same one, is now maybe 20 feet further into the bushes and in a culvert/pipes. So the bushes must have spread outwards over the last 50 years or so into the field.
I wonder how long it will take before high flows undercut the steep banks of the Valley Park and cause landslides? The most likely place is on the bend of a river where water flows faster on the outside of the bend. That would be at the bottom of the slope near St. Brigid's Well, the location of the so-called "Sally Hole": an area of river bed likely scoured out by the river. We really need a submersible to investigate, something I'd like to build if I ever get a chance (not manned 🙂, something like a drone). Whether it will happen depends on lots of factors including the nature of the soil, the gradient and hence speed of the river, how well the roots of trees anchor the soil, and so on. 

The area of riverbank is now possibly covered with bushes. © Eugene Brennan