Bedforms of the middle reaches of the Tay Estuary, Scotland

The distribution of bedforms in part of the middle reaches of the macrotidal Tay Estuary, Scotland, has, for the first time, been surveyed systematically using side-scan sonar. The main bedform types recorded were dunes of various sizes and morphologies, with small wavelength dunes occupying most of the channel areas. Dunes of three wavelength classes (small, 0.6-5.0 m; medium, 5.0-10.0 m; large, 10.0-100.0 m) were recorded on Middle Bank, a major sand bank that divides the study area into the main Navigation Channel to the south and Queen's Road Channel to the north. Medium height dunes (0.25-0.50 m) are the dominant dune height class in the study area, characterizing Middle Bank as well as most channel areas. Dune dimensions measured from sonographs were examined in terms of intercorrelations of wavelength, height and corresponding water depth. Although some researchers have found significant correlations between these variables in flume experiments and in field studies of intertidal environments, dune height and wavelength were not correlated or weakly correlated with water depth in this study. It is suggested that the relationships between these parameters established previously are not generally applicable in estuarine environments.