Entry and Deposits of Suspended Particulate Matter in Groyne Fields of the Middle Elbe and its Ecological Relevance

Abstract

AbstractGroynes are widespread in the Middle Elbe River. They are important for navigation during low water. Due to the significant decrease of the flow velocity in comparison to the main stream, sedimentation of fine organic matter in the groyne fields (the area between two groynes) is high. The amount and location of sedimentation depend on hydraulic processes. The present paper presents the results of the actual (recent) sedimentation, and of the matter deposited in a typical groyne field in the Middle Elbe at Havelberg (German navigation km 420.9/river length 785.4). Furthermore, the development of water quality and suspended matter is described by the interpretation of data from an adjacent official water quality measuring point. From an ecological point of view, the high loads of nutrients and pollutants of the fine‐grained sediment (mud) are of special interest. A close correlation was observed between the nutrient and pollutant load with the fine‐grain size percentage and the content of particulate organic matter (POM). Groyne fields act as temporary sediment deposits, and are a latent danger to the ecosystem river Elbe. During construction work carried out at the river and extreme floods the mud could be remobilized, leading to a decrease in the water quality of the Elbe. Therefore, it is desirable that the organic mud should be removed from the river and deposited in a controlled landfill.