Most of the Fenland lies within a few metres of sea level. As with similar areas in the Netherlands, much of the Fenland originally consisted of fresh- or salt-water wetlands, which have been artificially drained and continue to be protected from floods by drainage banks and pumps. With the support of this drainage system, the Fenland has become a major arable agricultural region in Britain for grains and vegetables. The Fens are particularly fertile, containing around half of the grade 1 agricultural land in England.