Also known as the Moselle Brook, originally a tributary of the River Lea, but now flowing into Pymmes Brook, another tributary of the Lea.
The Wikipedia page is [1], and that on the French river is [2]
The name derives from 'Mosse-Hill' in Hornsey, the high ground containing one of the river's sources, and bears no direct etymological relationship to the major continental Moselle River.[1] The hill area also gave its name to the district of Muswell Hill and for a time the river was known as the Moswell.
Although long stretches have been culverted (Moselle Avenue in Noel Park runs above the culverted river), it does not disappear into the London sewer system and much of its route can be easily traced. It can be seen flowing overground in Tottenham Cemetery and Lordship Recreation Ground, and gave its name to the Broadwater Farm area between the two.
London's Lost Rivers page [3].