Discussion on ‘The littoral sediment budget between Selsey Bill and Gilkicker Point, and its relevance to coast protection works on Hayling Island’ by D. A. Harlow

Abstract

The author is to be congratulated on this interesting paper, the implications of which extend beyond purely local considerations in terms of coastal protection schemes and coastal zone management. It is also encouraging to note that sediment sampling was achieved by diving and ‘visiting the actual environment, so that it can be described in qualitative detail’. This technique has much to commend it. The conclusions on erosion and littoral drift indicate the extreme importance of considering coastal units in which closed cells of sediment movement may occur. However, the author has omitted to place the model he develops into a wider or longer term context. The coastal area between Selsey Bill and Gilkicker Point is extremely interesting on a number of counts. For example, each harbour entrance possesses double northward recurving sand or shingle spits. The process of recurving is not explained, yet is of obvious relevance to the origin and development of the landforms observed in this coastal unit. A ‘Cuspate type’ foreland exists also at the south-western end of Portsea Island (now largely built over) in addition to Gunner Point on Hayling, indicating a very long history of longshore current driven sediment accumulation in these areas. The strong ebb tidal currents in the harbour entrances, e.g. 5.3 knots (at springs) through Chichester and 4.5 knots at Langstone, probably operate to feed offshore bars such as the West and East Winner banks off Langstone Harbour entrance and the East and West Pole sands off Chichester entrance. This is not