THE EFFECT OF GROUNDWATER ON SCOUR NEAR STRUCTURES

Abstract

A previously unreported mechanism which is believed to be a key process in the formation of shingle beaches is identified. It is proposed that this mechanism be called "winnowing". Several new considerations relating to the selection of appropriate model sediments for shingle beach models are discussed. It is shown that lightweight sediments are subject to a significant scale effect and a compromise solution is suggested. The results of some experiments, never previously performed, of beach scour in front of sea walls resulting from various combinations of wave attack and groundwater flow in the beach are presented. These show that the presence of groundwater flow in the beach has a significant impact on the amount of toe scour to be expected.