The Tweed catchment in Northeast Britain straddles the national and administrative border between English Northumberland and the Scottish Borders. The Tweed catchment is bounded to the North and West by the Lammermoor and Moorfoot Hills and to the South by the Cheviots which form part of Northumberland National Park. These upland areas are characterised by rounded hills with steep valleys or cleuchs eroded into their sides. The uplands eventually give way to the more open, rolling lowlands to the East, with flatter, more fertile land. The Borders is noted for its diverse and traditional landscapes which have helped sustain a rich variety of habitats and species, this is reflected in the designation of the River Tweed and its major tributaries as both a Site of Special Scientific Interest (SSSI) and a Special Area of Conservation (SAC).
