Security of stepped masonry spillways: lessons from Ulley dam

The stepped masonry spillway at Ulley dam, near Rotherham, UK, failed during a flood on 25 June, 2007. Ulley reservoir was completed in 1873, and the average age of British dams is now about 110 years, so there are many spillways which predate the introduction of concrete and where masonry was used. This paper reviews the hydrodynamics of such spillways so that such lessons, coupled with data from previous research into stepped spillways, can be used by engineers assessing similar works in future.