Geomorphic evolution of the Great Yarmouth coastal system : spit sediment dynamics and forcing mechanisms

Abstract

Little is known of the volume of sediment held within the Great Yarmouth spit or its short-term fluctuations in sediment storage capacity. Such gaps in coastal sediment budgets mean that the effects of predicted future increases in relative sea level and storminess are difficult to forecast. The current study addressed this by examining the late-Holocene geomorphic evolution of the Great Yarmouth spit, providing a value for the volume of sediment stored within the feature and placing current morphological changes within an historical context. The specific aims of this research were to investigate: (1) spit volume, (2) spit morphological change (3) potential forcings for this change and (4) likely future morphological trends. Short-term fluctuations in the Great Yarmouth spit’s sediment storage capacity were identified by investigating morphological changes within the feature’s coastal zone from map and aerial photograph evidence. These fluctuations appear to be site-specific across the Great Yarmouth spit and adjacent areas. Indeed, between 1800 and 2007 Winterton-on-Sea experienced accretion whilst coastline retreat followed by a period of relative stability typified trends at Caister-on-Sea. North Denes shows sea-ward advance of the coastline but this occurs after a phase of erosion prior to 1890. Great Yarmouth Pleasure Beach and Gorleston-on-Sea have remained relatively stable after a similar phase of pre-1890 erosion. All sites investigated are currently (2008 data) displaying either maintenance of or an increase in sediment storage capacity within the stable spit area (that above normal tidal conditions) with the exception of Caister Point which is undergoing erosion