The Avon begins as two separate rivers. The western Avon rises to the east of Devizes, draining the Vale of Pewsey, and the eastern Avon rises just east of Pewsey adjacent to the Kennet and Avon Canal. These two merge at Upavon, flowing southwards across Salisbury Plain through Durrington, Amesbury and Salisbury. To the south of Salisbury it enters the Hampshire Basin, flowing along the western edge of the New Forest through Fordingbridge and Ringwood, meeting up with the River Stour at Christchurch, to flow into Christchurch Harbour. The harbour opens into the English Channel past a cluster of small mouths of brooks from the New Forest and a broad sandbank, which is all built up as the Mudeford part of the harbour.