The Ordnance Survey released new Open Data datasets in March 2015, including a comprehensive shapefile of watercourses, the Open Rivers dataset. Being interested in groundwater-fed rivers I was curious to see the distribution of ‘bournes’ (typically ephemeral groundwater-fed streams). A map I made of the top six watercourse names is here.
I expected almost all ‘bournes’ would be chalk groundwater-fed streams but the Midlands has a lot of ‘bournes’ too. Mostly in the Midlands these are named ‘Bourne Brook’, a tautology (like all the River Avons). There is a handful of River Bournes as well.
But most of the ‘bournes’ are associated with the outcrop of the Chalk aquifer, as expected. A bourne is a small stream, which is typically ephemeral. Bournes that flow through the Chalk Downs are often associated with groundwater flooding – especially in the upper reaches which flow seasonally.