Irish Sky Garden, Chelsea Flower Show 2011
The Rill Garden, Coleton Fishacre by Derek Harper, via Geograph
BBC - Tyne - In Pictures - The Alnwick Garden rill
Simple rill and could be in keeping with grass/prairie plantings.
Garden Water Features in Sussex, Surrey, Kent and London by Barry Holdsworth
So glad I know the name now. I had this on my dream home plans for years. Reflective. Water runnel formal garden feature - Lezarde project 2013
Try using a rill like this as a focal point in your garden! More dream water gardens: http://www.bhg.com/gardening/landscaping-projects/water-gardens/dream-water-gardens/?socsrc=bhgpin063013rill=13
Peace Awareness Garden LA - Mosaic rill