Tidal Exchanges Between Orplands Managed Retreat Site and the Blackwater Estuary, Essex

Abstract

Abstract ‘Managed retreat’ is a salt‐marsh restoration technique which is under experimental implementation in the UK. The technique involves the engineered tidal inundation of coastal land in front of re‐aligned flood defences. Salt marshes developed by this method are intended to act as hydraulic buffers in front of coastal defences and to provide zones of environmental enhancement. Two managed retreat trials were instigated in 1995 on the Blackwater Estuary, Essex, UK. In June 1995, two months after breaching the seawalls, the initial environmental impact and geochemical development of the Orplands managed retreat site were investigated by surveys of tidal exchanges. Tidal stage curves and quantities of exchange were determined by four hydrological surveys at the extremes of a neap‐spring tidal cycle, and the chemistry of exchanges was investigated by water sampling during these surveys.