The River Effra rises in the hills of south London and picks its way to the Thames through Herne Hill, Brixton and Lambeth. It's mostly buried, and used as a sewer, so you can't normally see it. You can, however, hear it... at least at the Floodtide on the Effra event on 18 May.
The fun starts in Belair Park, Dulwich, where you pick up a route map. You then make your way to various nearby locations on the Effra route. At each stop, you'll experience something a little unusual:
Floodtide is a music work by composer and yachtsman John Eacott. A sensor reads the movement of water in the river Effra and translates it, with the help of computer software, into musical notation. Local performers will read the notation live from screens, providing a changing and unpredictable symphonic portrait of the waterway.
This being a live interpretation of a sewer, the recitals might — dare we say it — include a few bum notes. But it's sure to be an unusual event, with beatboxers, choirs and other musicians all playing the Effra.
More info and location timings can be found on the event's Facebook page or website. The promenade performance is free, and you can just turn up on the 18 May. The event is supported by Southwark Council. #FloodtideOnTheEffra