Spatial variability of metal pollution in groyne fields of the Middle Elbe--implications for sediment monitoring.

Flood-event based metal distribution patterns in water as approach for source apportionment of pollution on catchment scale: Examples from the River Elbe

All over the world, river basins are under pressure from human activities that affect their chemical and ecological statuses and exhaust available natural resources. Sediment is an essential, integral and dynamic part of the river basins and sediment issues may affect various environmental, social and legal objectives pursued there. Sediment management becomes necessary if the intensity of anthropogenic interventions in the sediment status overwhelms the resilience of ecologic endpoints of the river system or if sediment dynamics and/or sediment status strongly affect human uses. Despite the progress that has been made in the knowledge of sediment management during the last 20 years, practical examples of comprehensive river-basin-scale sediment management concepts are by no means state-of-the-art, and even concepts that focus on only one of the sediment issues are sparse. In Europe, approaches to the management of waters have been radically altered with the introduction of the European Water Framework Directive (WFD). The International Commission for the Protection of the Elbe (ICPER) had declared good sediment quality as one of its key targets. The first Elbe management plan prepared under the WFD (2010–2015) highlights contamination and insufficient hydromorphological conditions as two of the most important supra-regional issues in water resources management. The plan underlines that contaminated sediments and unbalanced sediment conditions are among the main reasons for the failure to meet the WFD management objectives. As a consequence, the member states in the ICPER decided to develop a sediment management concept in preparation for the management cycle from 2016 to 2021. For the first time, an integrated sediment management concept was developed in support of management planning in a large international river basin. The concept is related to the river basin, i.e. it considers cause-effect relations in the entire river basin district Elbe. It combines the issues of sediment quantity, hydromorphology, and sediment quality as well as ecological and use-oriented sediment aspects in one concept. The conclusions rely on analyses of risks resulting from an insufficient status of the sediment budget, ecological functions, ecosystem services, and sediment-dependent uses of the river.

Sediment Management on River-Basinscale: The River Elbe

River water quality is still a vital environmental issue, even though ongoing emissions of contaminants are being reduced in several European rivers. The mobility of historically contaminated deposits is key issue in sediment management strategy and remediation planning. Resuspension of contaminated sediments impacts the water quality and thus, it is important for river engineering and ecological rehabilitation. The erodibility of the sediments and associated contaminants is difficult to predict due to complex time depended physical, chemical, and biological processes, as well as due to the lack of information. Therefore, in engineering practice the values for erosion parameters are usually assumed to be constant despite their high spatial and temporal variability, which leads to a large uncertainty of the erosion parameters. The goal of presented study is to compare the deterministic approach assuming constant critical erosion shear stress and an innovative approach which takes the critical erosion shear stress as a random variable. Furthermore, quantification of the effective value of the critical erosion shear stress, its applicability in numerical models, and erosion probability will be estimated. The results presented here are based on field measurements and numerical modelling of the River Elbe groyne fields.

http://ksh.fgg.uni-lj.si/bled2008/cd_2008/05_Floods,%20morphological%20processes,%20erosion,%20sediment%20transport%20and%20sedimentation/054_Prohaska.pdf

Sandra Prohaska

Papers

Model based estimation of sediment erosion in groyne fields along the River Elbe