Sediment Character in a Micro-Tidal, Harbor-Estuary Environment, Göteborg, Sweden

Abstract

Harbor-estuaries are complex sedimentary environments where both natural and anthropogenic processes influence the distribution and accumulation of sediments, which in turn is of importance for maintenance dredging and pollution control. This paper uses sediment characteristics from the Gota alv estuary, Sweden to evaluate the natural estuarine processes that persist despite the extensive human impact on the estuary and to separate and characterize depositional sub-environments. The most important harbor processes include maintenance dredging and turbulence from ship traffic, and their influence upon shallow stratigraphy and sediment distribution and deposition is significant. Polymodal particle-size distributions are interpreted to reflect the natural estuarine transport processes. Suspension transport is generally predominant, except in the river and inner harbor where bottom transport and selective deposition of sand occur. Particle-size characteristics divide the estuary into four depositional areas: the river and the inner, middle, and outer harbor. The shallow stratigraphy reveals a hiatus between the firm silty clays and the loose recent sediments. The hiatus in the stratigraphy is probably related to dredging in most areas of the harbor. Significant maintenance dredging and turbulence from ship traffic also influence the accumulation (0–61 cm) of recent sediments, during the 20th century.