Canvey Island barriers spanning Benfleet Creek to the north and East Haven Creek in the west. The drainage system consists of sewers, culverts, natural and artificial dykes and lakes which feed seven pumping stations and gravity sluices that discharge the water into the Thames and creeks. Four of the discharge sites are "high flow" stations capable of discharging 600 litres of water per second at any tide level. The levels within the system are managed by a further five "low flow" pumping stations. The Environment Agency's Thames Estuary 2100 flood defence plan includes Canvey Island as one site for alleviating the flood
Wouri estuary are divided by the Dibamba River and by Monaka Bay and Island. About of the mangrove forest is within the Mouanko Reserve, which extends from the south shore of the estuary to the Sanaga River mouth. The mangrove "Rhizophora racemosa", which makes up over 90% of mangroves in Cameroon, reaches a height of in the Wouri estuary. "Nypa fruticans", an exotic species imported to Nigeria from South-East Asia, has been spreading quickly, encouraged by the local people. The mangrove forests are an important source of wood for making furniture and fences, for smoking fish and for fuel. The leaves of