The role of contaminated sediment monitoring for dredging management in the Elbe estuary
Carmen Kleisinger, Mandy Hoyer, Birgit Schubert
Federal Institute of Hydrology (BfG), Koblenz, Germany
1 folio 1 The Federal Waterway Elbe
Elbe: Total length: 1094 km Poland Length estuary: 183 km UK
Germany Czech Republic France Austria Switzerland
Geesthacht Weir
Port of Hamburg
2 folio 2 The Federal Waterway Elbe
The tidal Elbe is an important waterway including the Port of Hamburg, the third largest port in Europe
More than 60,000 ships per year
Important to maintain the waterway
Container handling
3 https://www.hafen-hamburg.de/de/statistiken/containerumschlagfolio 3 Dredging in the Elbe estuary
Amount of dredged sediments in million m³- Federal Waterways and Shipping Authorities
Mean: 12.2 million m³/a (1987-2017 average) No significant change in the volume of dredged sediments
12.2 million m³
Amount of dredged sediments in Mio. m³ - Hamburg Port Authority 14
12 Increase of the volume of dredged sediments 10 Graph modified after: Federal Waterways and Shipping Authorities 8
Shift of dredging sections 6 into the estuary over time 4
Increasing volume of 2 dredged sediments in the Port of Hamburg 0 4 Data: HPAfolio 4 Dredging in the Elbe estuary
Dredger in the Elbe estuary Dredging management strategies are essential
Actual Dredging Recommendation for dredging management management in the Elbe estuary - discharge-independent - Low discharge conditions
High discharge conditions How can contaminants help to develop High management strategies? discharge conditions
Low discharge conditions
5 folio 5 The Role of contaminants in dredging management
In Germany the impact of relocations has to be estimated
Questions:
The fate of dredged sediments after relocation The impact of the sediments on the environment (chemical and ecological)
Requirement:
Understanding the system
Approach to answer the questions:
Monitoring the system and the dredging activities
Result:
Optimization of dredging management
Contaminants act as tracer and help to understand transport pathways 6 folio 6 The Role of contaminants in dredging management Monitoring activities in the Elbe estuary – understanding the system
Monitoring stations 1 Cuxhaven, Kugelbake (BfG) 2 Cuxhaven (FGG Elbe) 3 Brunsbüttel (BfG) 4 Grauerort (FGG Elbe) 5 Bützfleth (BfG) 6 Wedel (BfG) 7 Seemannshöft (FGG Elbe) 8 Bunthaus (FGG Elbe) 9 Geesthacht (BfG)
Port of Hamburg
Monitoring stations (BfG or River Basin Community Elbe (FGG Elbe)): • Monthly sampled suspended particulate matter (SPM) or fresh sediments (not older than 4 weeks)
• Partly operated since the 80s long time series 7 folio 7 The Role of contaminants in dredging management Monitoring activities in the Elbe estuary – understanding the system
Time series
Mercury
Monitoring station Wedel
Decreasing contaminant concentrations over time
8 folio 8 The Role of contaminants in dredging management Monitoring activities in the Elbe estuary – understanding the system
Time series Copper Monitoring station Wedel
Discharge in Neu Darchau Elbe km 536
Contaminant concentrations are discharge-dependent 9 folio 9 The Role of contaminants in dredging management Monitoring activities in the Elbe estuary – understanding the system
Mercury Monitoring stations 3 1 9 6
Decreasing contaminant concentrations within the estuary Contaminant input from the upper Elbe
10 folio 10 The Role of contaminants in dredging management Monitoring activities in the Elbe estuary – understanding the system
RelocationVS 689 R area
Q [m³/s] in Down- Up- stromab [%] stromauf [%] Neu Darchau stream [%] stream [%] 180 10 90 720 43 57 1260 80 20
Contaminant load transported upstream and downstream
14 2.000.000
HCB 12
in kg in 1.500.000
10
load sediments
8 1.000.000 Source: Federal Waterways Engineering 6 and Research Institute (BAW) t in
4 dredged
500.000 t in µm 63 < • Since 2013 very low discharge conditions in the 2 of
upper Elbe River Contaminant Schadstoffmenge in kg in Schadstoffmenge • Increasing load of sediments to be dredged 0 0 Load
• Decreasing contaminant load 2012 2013 2014 2016 2017 µm<63 Baggergutmenge • Repeated dredging of same sediments Down- Up- Load of dredged sediments in • Long residence time of contaminants in the estuary stromabstream stromaufstream Baggergutmenge< 63 µm in t in < 63 µm11 (t) folio 11 The Role of contaminants in dredging management Monitoring activities in the Elbe estuary – understanding the system
Monitoring of dredging activities – dredged material and relocation sites
Hamburg Grab sampler used at dredging sections (annual)
Dredging sections with fine-grained sediments 12 folio 12 The Role of contaminants in dredging management Monitoring activities in the Elbe estuary – understanding the system
Contaminant concentrations downstream dredging sections BA 1 to BA 12 (2010 and 2014)
18 BA 5 BA 3 BA 7 16
BA 1 14
12
10
8 BA 12 6
4 Concentration µg/kg in Concentration (in 63 < µm)
2
Elbe km 0 710 700 690 680 670 660 650 640 630 p,p-DDD p,p-DDD 2014 <= North Sea Port of Hamburg => 13 folio 13 The Role of contaminants in dredging management Monitoring activities in the Elbe estuary – understanding the system
Monitoring of dredging activities – dredged sediments and relocation sites
20 sediment cores (every two years) 50 cm – 120 cm depth
15 folio 15 The Role of contaminants in dredging management Monitoring activities in the Elbe estuary – understanding the system Contaminant concentrations in sediment cores over time
Mercury (Hg)
Concentrations increase with depth More or less constant concentrations in the upper layers – comparable to current Hg concentrations in the SPM 16 Erosion and deposition in balance at most sites folio 16 Lessons learned
• Decreasing contaminant concentrations over time • Decreasing contaminant concentrations of sediments downstream the estuary • Discharge-dependent contaminant concentrations High discharge high contaminant concentrations – the upper Elbe River is the source of contaminants (except for TBT) Low discharge low contaminant concentrations • Long-lasting low discharge conditions Huge amount of dredged sediments – dredging in a circle First: accumulation of contaminants in the estuary High contaminant loads Second: dilution of contaminant concentrations in the estuary by the high amount of little contaminated marine sediments • Long-lasting high discharge conditions First flush – very high concentrations Concentration level remains high • Higher contaminant concentrations in deeper layers • At most sites erosion and sedimentation in balance
Recommendations for dredging
management in the Elbe estuary 17 folio 17 Recommendation for dredging management in the Elbe estuary
Adaptive dredging management in the Elbe estuary – discharge dependent
Actual dredging management - Discharge-independent -
Low discharge conditions
High discharge conditions
High discharge conditions
Low discharge conditions
The results of contaminant monitoring are one component for dredging management recommendations! 18 folio 18 Thank you for your attention
19 folio 19