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Shoreline Management Coastal Features - Ridge and Runnel One of most interesting features found on the Sefton Coast is the Ridge and Runnel System that occurs on large areas of the foreshore. Definition Ridges are areas of the foreshore that are raised above the adjacent shore which dips into a Runnel. The cross-section is similar to that of hills and valleys. Theses features can be picked up on various surveys but most noticeably on beach profile surveys, as shown below. Formation Ridge and Runnel Systems are formed due to the interaction of tides, currents, sediments and the beach topography. They will only form on shallow gradient beaches. When low tides coincide with strong onshore winds, blown sand can accumulate in the runnels to the point that the beach surface is almost flat. Survey and Monitoring As mentioned earlier beach profiles are very good at detecting these features. The beach profile only picks up a small cross section of the profile but in a lot of detail. Analysis of the beach profiles show that these features are not static on the shore and do move up and down across the profile. Aerial photography also picks up the extent of these features on a large scale but does not allow any height measurements to be taken. Home Page - Top www.seftoncoast.org.uk

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