Lecture by Dr. Simon Ferley
Wednesday 12th October 2016
Dr Ferley began from first principles. He considered the properties of soil and the way it’s strength varied with water content, which he demonstrated with samples from his own garden. He then went on to describe the different ways in which slopes fail with some mathematical equations enhanced by some very clear diagrams. It became abundantly clear that water content is crucial to the stability of any slope and that appropriate drainage is essential to prevent failure.
He then discussed measures which could be taken to mitigate naturally occurring failures. These included good maintenance of channels downstream, delaying flow in areas nearer the catchment by tree planting and creating artificial meanders in a stream. He was cautious about flood defences as although they are necessary in some areas, they may exacerbate problems downstream.
Dr. Ferley had some dramatic photographs of rock and soil failures both from this country and abroad, almost all due to inappropriate engineering works rather than natural events.
He finished with a quick resume of the cause of the devastation to the A591 which had been due to excessive rainfall that had, by natural processes, been channeled into a steep, narrow gully.
Susan Beale
