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Harbours - silting and environmental sedimentology

Objective

1.Identification of the sediment sources, transport pathways and deposition in a harbour setting having limited tidal influence.

2. Evaluation of the geographic and vertical associations between sediment components and the geo-chemical transfer mechanisms involving pollutants, with particular reference to bottom turbulence.

Establishment of a generic model for component and process quantification, and to suggest model scenarios involving dredging and environmental change in harbour settings.
Conclusions:

Within the objectives of the Transport Programme (4th point) the need to reduce damage to the environment was stressed, which is of particular concern with dredging operations, as noted within the Maritime Transport research tasks for Ports, Environment and Safety (6.3.5). Our project has attempted to address concerns related to harbour surveying and dredging impact (within Research Task 6.3.5/35) with links to ongoing port activities (Task 6.3.5/33) as these can influence the sediment character, with dredging itself a major environmental feature affecting more than just the sediment itself. The H-SENSE project has addressed both the methods of hydrographic surveying and the applications of these data for dredging management and environmental protection. Detailed facies characterisation and sediment transport dynamics have been conducted in order that the most appropriate sediment treatment and removal techniques can be applied. The problem of polluted sediments was addressed, not just looking at the surface sediments, but down profiles as dredging operations generally remove the top 50cm layer with associated remobilisation problems of pollution stored within older sediments. GIS and geostatistical analyses have also been carried out so that the most cost effective sampling regime can be suggested balancing cost of sampling with the potential costs of incorrect disposal if too few samples are collected to detect trends. Different approaches to modelling surface trends were evaluated as though interpolation can give a visually impressive result there are problems when considering the statistical description of a chosen variable. Also GIS modelling has attempted to predict surface conditions without the variable of interest being used in the calculation providing a method which may further reduce the cost of the monitoring schemes currently employed.

The release of pollutants from storage forms a hazard whose effects have to be quantified within the risk analysis, and subsequently managed in a manner appropriate to the ecosystem, feasible regarding operation of the harbour, and consistent with respect to legislation.

There is no simple solution to the problems created by polluted marine sediments. Such sediments, particularly if fine grained, tend to absorb chemicals including potential contaminants such as polychlorinated biphenyls (PCBs) and polyaromatic hydrocarbons (PAHs). Contamination may be limited to a "hot spot", but is commonly diffuse, and its distribution strongly influenced by the history of sedimentation and anthropogenic, particularly urban, industrial and agricultural activities in the region. Furthermore, changes upon burial and with time are significant for most elements and depositional settings.

A risk-based approach is currently advocated (NRC, 1997), providing a systematic basis for management practice and application of appropriate technologies. The broader remit requires consideration of best management practice, regulations, source control and site assessment. The overall goal is to manage the system on such a way that the outcomes are optimised. Trade-off between resource limitations and remediation efficiency requires a basis for comparison, usually effected by optimisation of cost. This necessitates the risk-based approach.

Uncertainties about the nature and significance of chemicals in given concentrations on the ecosystem and/or human health is a major stumbling block, hindering development of such areas. This increases the necessity for quality assurance, demonstrating through an audit trail how a particular management strategy has been developed, and the basis for the decisions made. The generic modelling developed within Work Package 3 provides a basis for such auditing.


4. Collaboration Sought:

We see the H-SENSE project as a platform for several developments that will involve both project participants and new contacts. The results of our investigations have only been tested upon a limited basis. Therefore, the consideration of the application possibilities in several, new harbour settings would be extremely valuable. These new ventures could involve any part of the project results, ranging from site-survey techniques (e.g. geophysical methods, bottom-sediment classification, transport pathway interpretations) to geochemical evaluation (e.g. multi-parameter normalisation for site comparisons, combined physical and geochemical classifications) to modelling (e.g. ANN, geostatistical, and other modelling approaches).

We will continue to utilise the network that has resulted from our cooperation during the H-SENSE project, but it is obvious that exchange with other groups would be appropriate and necessary for new developments. Our activities have strengthen the Baltic Sediment Network, a larger group in which GU, SGSL and UL have participated. We have also contact with the European Sediment Research Network (SedNet) initiated by the Port of Rotterdam. We also hope to utilise the European SeaSed website and network for scientific data exchange. It would be most ideal to further strengthen network activities and to make the integration of results more feasible for the participants through direct EU support. In particular, we wish to contribute to an increased exchange between end-user and scientific groups, where the goals of monitoring, processes studies, and remedial or preventive action are more fully integrated.


5. Exploitation and Dissemination Plans:

We have primarily aimed at producing technical reports with the quality and character required for publication in scientific and engineering journals and conference volumes. Our participation in conferences has also been of central importance for our goals and to maintain an active dialogue with colleagues. During 1998 and 1999, we made presentations and published papers and abstracts at several conferences, including those organised by the Nordic Society for Clay Research (Lund, October 1998), the Royal Geographical Society, Institute of British Geographers (Leicester, January 1999), and the International Harbour Congress (Antwerpen, September 1999). This last meeting was in a session on the "Characterisation and treatment of sediments", which is closely related to our project and offered a good opportunity for publication of H-SENSE results with six papers presented in the conference proceedings. All of our reports and, of course the published papers, are intended for general dissemination.

A Newsletter series was started containing information on recent activities, results and plans of the H-SENSE project. The first Newsletter was printed and distributed in June 1998. A poster presenting our project was on display at the "Third European Marine Science and Technology Conference" in Lisbon, Portual in May, 1998. Newsletter #1 was also distributed at this conference to the visitors at the Göteborg University booth.

We are currently preparing a special volume dealing specifically with the H-SENSE results for "Environmental Geology", the leading international journal within this field. All of the partners have contributed and four of the 10-12 planned articles have already been review and accepted for publication. Publication is planned for 2001. Another opportunity is a "benchmark" volume being compiled by NTU, entitled "Problems of Silt and Siltation". This topic is has been chosen in part because of the on-going activities within H-SENSE, and the H-SENSE results that will complement active research a within other related areas. Stevens has submitted an article on "Problems of siltation in harbours".

Our Homepage (http://hjs.geol.uib.no/Hsense) continues to be our main "window" to the outside world, and this site is increasingly visited by non-H-SENSE visitors. Hans Schrader has created a first-class site for all H-SENSE-related information that we believe will provide information for both specialists and laymen alike. The value of this medium is also evident in that it can reach general audiences and create a wide interest for harbour issues that would be hard to generate in other ways. Our H-Sense web page is registered and acknowledged by all major search robots; besides simple html documents this web page also contains several interactive cgi utilities that allow in-time on-line interaction. We can monitor all traffic. There are also specialized FTP and web-server areas that are presently restricted in their access rules.


Publications (to date) from the H-SENSE Investigations
(not including abstracts)


deliverables:
D1 - 1998: Project Manual, 9 pp, (9 appendixes). H-SENSE Deliverable to EC DG-VII (Transport).
D2 - 1998: Data and Method Priorities regarding sediment investigations of harbour sites. Submitted October 15, 1998. H-SENSE Deliverable to EC DG-VII (Transport).
D3 - 1999: Summary of Harbour Surveys, Sediment analyses and Initial Interpretations in the Bergen, Göteborg and Ventspils Harbours, 52 pp. H-SENSE Deliverable to EC DG-VII (Transport).
D4 - 1999: Modelling Alternatives, 27 pp. H-SENSE Deliverable to EC DG-VII (Transport).
D5 - 2000: The environmental Sedimentology Model: Applications and Limitations, 54 pp. H-SENSE Deliverable to EC DG-VII (Transport).
D6 - 2000: - Characterisation and Evaluation of Harbour Sediments (Recommendations from H-SENSE), 47 pp. H-SENSE Deliverable to EC DG-VII (Transport)

Scientific papers
Brack, K. & Stevens, R.L. 1999: Environmental significance of sediment units and their variability in the Göta älv estuary. Accepted for publication in CATS 4 (Proc. Intern. Congress on Characterisation and Treatment of Sediments, Antwerpen, Sept. 15-17, 1999), 299-308.
Brack, K. Stevens, R.L. & Paetzel, M. 2000: Holocene environmental change and the accumulation-erosion balance of sheltered river-mouth sediments. Göteborg, SW Sweden. Marine Geology, 170, 347-362.
Brack, K., Johannesson, L.T. & Stevens R.L. in press: Accumulation rates and mass calculations of Zn and Hg in recent sediments, Göta älv estuary, Sweden. Environmental Geology.
Brack, K. & Stevens, R.L. in press: Historical pollution trends in a disturbed, estuarine sedimentary environment, SW Sweden. Environmental Geology.
Burton, C.L., Rosenbaum, M. Stevens, R.L. & Book, S.H. 1999: Creating a harbour sediment database. Accepted for publication in CATS 4 (Proceedings International Congress on Characterisation and Treatment of Sediments, Antwerpen, Sept. 15-17, 1999), 575-584.
Engström, L. E. & Stevens, R.L. 1999: Multi-parameter normalisation of geochemical data from the Göteborg Harbour. Accepted for publication in CATS 4 (Proceedings International Congress on Characterisation and Treatment of Sediments, Antwerpen, Sept. 15-17, 1999), 159-168.
Johannesson, L., Stevens, R. & Alexanderson, J.H. in press: Sediment characteristics in a micro-tidal, harbour-estuary environment, Göteborg, Sweden. Estuaries (planned publ. June 2000)
Larsson, L.B. & Stevens, R.L. 1999: Time-dependent changes of PCB and mercury in harbour channel sediment, Göteborg, Sweden. Accepted for publication in CATS 4 (Proc. Intern. Congress on Characterisation and Treatment of Sediments, Antwerpen, Sept. 15-17, 1999), 71-80.
Rosenbaum, M.S. & Stevens, R.L., 1998. Problems arising from silt within harbours. GeoScientist, 8(12), 22, ISBN x 24 042 706 7, ISSN 0961 5628.
Rosenbaum, M.S. & Stevens, R.L., 1999. Problems of silt and siltation in harbours. In: Turnock, D. (Ed.) Geographies of the Future. Annual Conference of the Royal Geographical Society - Institute of British Geographers, Leicester, 167.
Stevens, R.L. 1999: H-SENSE: sediment perspectives upon harbour sustainability. Accepted for publication in CATS 4 (Proc. Intern. Congress on Characterisation and Treatment of Sediments, Antwerpen, Sept. 15-17, 1999), 617-624.
Stevens, R.L., Engström, L.T., Brack, K. 1999: Harbour sediment documentation for future, undefined purposes. Accepted for publication in CATS 4 (Proc. Intern. Congress on Characterisation and Treatment of Sediments, Antwerpen, Sept. 15-17, 1999), 551-560.
Yang, Y. & Rosenbaum, M.S., 1999. Spatial data analysis with ANN: geoenvironmental modelling of harbour siltation. In: Shi, W., Goodchild, M.F. & Fisher, P.F. (Eds.) Proceedings of the International Symposium on Spatial Data Quality (ISSDQ'99), Hong Kong, 18-20 July, 534-541, ISBN 962 367 253 5.

Scientific papers submitted/under review (international journals)
Brack, K.: Organotin compounds in sediments from the Göta älv estuary. Submitted to Water, Air, and Soil Pollution.
Brack, K. & Johannesson, L.T.: Mercury and methylmercury in estuarine sediment and porewater, Göteborg Harbour, SW Sweden. Submitted to Applied Geochemistry.
Burton, C.L. and Rosenbaum, M.S.: Decision support to assist environmental sedimentology modelling. Submitted to Environmental Geology, H-SENSE Special Volume.
Burton, C.L. Rosenbaum, M.S. & Stevens, R.L.: Sedimentological considerations for predictive modelling. Submitted to Bulletin of the International Association of Engineering Geology and the Environment.
Johannesson, L.T. Stevens, R.L. & Eriksson, K.L.: The influence of an urban stream on sediment geochemistry in Göteborg Harbour, Sweden Submitted to Environmental Geology, H-SENSE Special Volume.
Johansen, L.M. Schrader, H. & Alve, E. Characterising state of pollution in the Bergen Harbour Area (Western Norway) with benthic foraminifera and sediment facies distributions. Submitted to Environmental Geology, February 2000.
Paetzel, M., Nes, G., Øystein Leifsen, L. & Schrader, H: Sediment pollution in the Vågen, Bergen harbour, Norway. Submitted to Environmental Geology, H-SENSE Special Volume.
Stevens, R.L.: Silt problems in harbours. Submitted to Jefferson, I. (ed.): Problems with silt and siltation. Thomas Tellford.
Stevens, R.L.& Ekermo, S.: Sedimentation and erosion in connection with ship traffic, Göteborg Harbour, Sweden. Submitted to Water and Maritime Engineering.
Yang, Y., Rosenbaum, M.S. & Burton, C.L.: An intelligent database for managing geoenvironmental change within harbours. Submitted to Environmental Geology (H-SENSE Special Volume).
Yurkovskis, A.: Remixing in the lower reach of the Venta River - Ventspils Harbour (Baltic Sea), effects on nutrient cycling and transport. Submitted to Environmental Geology (H-SENSE Special Volume).

Scientific papers in preparation for journal submission
Brack, K., Johannesson, L.T. & Stevens, R.L.: contaminant distribution and long-term fluxes in the recent sediments of Göteborg Harbour, Sweden (For Environmental Geology).
Burton, C.L. Rosenbaum, M.S and Stevens, R.L. Sedimentological considerations for predictive modelling (For Bulletin of the International Association of Engineering Geology and the Environment).
Johannesson, L.T. Stevens, R.L. & Eriksson, K.L.: The influence of an urban stream on sediment geochemistry in Göteborg Harbour, Sweden (For Environmental Geology).
Larsson, L & Stevens, R.L. Changes in the distribution of PCB and Hg influenced by Ship-induced turbulence in Göteborg Harbour (For Environmental Geology, H-SENSE Special Volume).
Maurenbrecher, P.M. & Alvarez Grima, M.: Estimating error in geophysical sub-bottom profiling.
Mueller-Karulis, B., Seglins, V. & Poikane, R.: Heavy metals in the Ventspils harbour. (For Environmental Geology Special Volume).
Paetzel, M. & Schrader, H.: Natural vs. Human induced facies-change in recent, shallow water sediments of the Store Lungegårdsvannet (Western Norway). (For Environmental Geology, H-SENSE Special Volume).
Schrader, H.: Foraminifera distribution in the Byfjorden, Bergen Harbour. (For Environmental Geology Special Volume).
Stevens, R.L. & Jonsson, R.: Sediment transport paths and siltation problems in Ventspils Harbour, Latvia. (For Environmental Geology, H-SENSE Special Volume).

Student Theses
Brack, K. 1999: Characterisation of facies and their relation to Holocene and recent sediment accumulation in the Göta älv estuary and Archipelago. Department of Geology, Göteborg 1999, Earth Sciences Centre, Göteborg University, A46. ISSN 1400-3813.
Brack, K. 2000: Göta älv estuary - evaluation of anthropogenic and natural influences. Ph.D. dissertation, Kiel Univeristy, 146 pp.
Ekermo, S. 2000: Accumulation and provenance of sediment in Göteborg Harbour. Department of Geology, Göteborg 2000, Earth Sciences Centre, Göteborg University, ISSN 1400-3821.
Engström, L. 1999: Sedimentology of Recent sediments from the Göta älv estuary - Göteborg harbour, SW Sweden. Department of Geology, Göteborg 1999, Earth Sciences Centre, Göteborg University, A40. ISSN 1400-3813.
Eriksson, K. 1999: Sedimentological and geochemical changes along the Stream Kvillebäcken and at its mouth within Göteborg Harbour. Department of Marine Geology, Göteborg 1999, Earth Sciences Centre, Göteborg University.
Jonsson, R. 2000: Sediments and Sedimentation processes in a disturbed esturine environment, Ventspils Harbour, Latvia. Department of Geology, Göteborg 2000, Earth Sciences Centre, Göteborg University, B216. ISSN 1400-3821.
Johansen, L.M. 1998: Bentiske foraminiferer og forurensing i Bergen havnebasseng, vest Norge. Master-Thesis Department of Geology, University of Bergen, March1998, 136 pp., with English abstract.
Leifsen, L. Ø. and Nes, G. 1999: The influence of external forcing on sedimentation and trace metal pollution in the Vågen, Bergen harbour (Norway). HSF-College, Semester thesis, May 1999.
Mathisen, A. & Torfinn Prestmo, H. 1999: Environmental sedimentology in the Vågen, Bergen harbour (Norway). HSF-Collelge, Sogndal, Semester thesis, May 1999. (in Norwegian).
Wever, T.P.A. 1999: Seismic interpretation of H-Sense data and sub-bottom characterisation using CHIRP sonar technology. Delft University of Technology, Master's thesis. Faculty of Civil Engineering and Geosciences, Applied Earth Sci., Eng. Geology, Delft, Febr. 1999.
Technical Description:

The H-SENSE project has used standard evaluation techniques for site survey incorporating geophysics, sedimentology and geochemistry. The project investigators come from a wide range of specialities to allow maximum diversity of experience. The approach to harbour sampling has been far more extensive than that required for routine site surveys to allow an evaluation of new techniques and to give suggestions for alternatives aimed at specific harbour problems.


Workpackage 1: Influences on Silting

In order to construct a comprehensive database and gain an understanding of sedimentary processes this workpackage has used a wide number of determinations. The large number of techniques employed in the project has resulted in positive recommendations for specialised purposes as well as for cost efficient routine measures. Methodological developments which may prove valuable to harbour surveys include digital documentation techniques, smear slide analyses, bottom surface classifications and mineralogical techniques for identification and budgeting of sediment sources.

Göteborg Harbour:
Göteborg Harbour is an example of a non-tidal salt wedge estuary. The harbour requires regular dredging as sediment in-filling is an evident problem, with clay sediments brought in through the Göta älv River. Within Göteborg Harbour a detailed sediment archive has been collected and utilised to identify sediment facies, evaluate sediment variability and propose a bottom surface classification integrating the sedimentological, geochemical and biological features. This integration is considered essential towards developing future classification concepts/schemes for contaminated sediment - a task which we feel out results can contribute to. CHIRP profiling has indicated that the record of siltation is very dynamic and the estuary is not only a zone of accumulation. Short-term (1996-1997) sediment accumulation and erosion rates have been also been calculated with high spatial resolution. The sedimentological conditions of Göteborg Harbour have been compiled as text, numeric determinations, photographic and digital images. The value of documentation has been addressed and has resulted in a detailed archive including primary data in the form of samples, which will be accessible to future harbour investigations. The Göteborg dataset has had particular value for the stochastic modelling, e.g. Artificial Neural Network (ANN) models.

Bergen Harbour
Bergen Harbour is an example of a highly polluted, low tidal, fjord system with no river input and highly variable bottom sediment conditions. Within Bergen Harbour a detailed sediment archive has been collected including a sediment facies classification and an evaluation of sediment variability. An evaluation of smear-slide analyses was conducted and Bergen has produced a smear-slide archive that is accessible to the public at the H-SENSE website (http://hjs.geol.uib.no/hsense/) and will be available for future harbour studies. An assessment of sediment sources has been conducted along with a sediment quality assessment using benthic microfossils. The result of long-term dumping of raw sewage and excavation material directly into the harbour was the main focus of the study with recommendations produced regarding remediation options and problems related to indiscriminate dumping of dredged material. The Bergen case studies have been of particular value for illustrating the sediment response to environmental change, both over time and geographically in these highly variable settings.

Ventspils Harbour:
Ventspils Harbour is an example of a micro-tidal, highly stratified salt-wedge estuary that is also strongly influenced by long-shore currents flowing northward. An expansion in international trade with increasingly larger vessels has resulted in an urgent need for deepening the port channel and thus an understanding of sedimentation processes is required. Within Ventspils Harbour a detailed sediment archive has been collected, including sediment facies and water-column nutrient and trace-metal chemistry. A detailed history of the siltation pattern and sediment volume within Ventspils Harbour has been reconstructed for the last century using historical data. Sources identification, sediment-budget calculations and the interpretation of transport pathways illustrate the potential of mineralogical and textural data combined with the trends documented in sediment geochemistry. The Ventspils case study is an application of the "sediment perspective" toward central problems for harbour management.


Workpackage 2: Environmental Geochemistry.

The objective of workpackage 2 was to establish a geochemical database within the three harbours ensuring quality control and suitable parameters for modelling. Furthermore, it was the aim of the H-SENSE study to gain an understanding of vertical as well as spatial trends since dredging and ship turbulence affects more than just the uppermost surface sediments and which could result in the remobilisation of old contaminants into the water column. Several tasks have been conducted which have dealt with process interpretations. There is a need to understand the processes causing changes that occur after deposition. Changes in depth have been shown to reflect sedimentation and environmental changes as well as the pollution history. There is a need to compare sites and this was addressed by considering different means of normalising the data, resulting in the recommendation of the multi-parameter method related to sedimentary characteristics for each setting. Current contaminant classifications used by most harbour authorities are not sensitive to mobility and toxicity of elements in different phases. The identification and evaluation of phase- specific metals is an important result from this study.

Göteborg Harbour:
External to the harbour the main source of contamination is the Göta älv River. Although the Göta älv River is considered less polluted by toxicants than many other European rivers, its sediments are a continuing source of elevated concentrations of priority organic pollutants and heavy metals. The geochemical archive produced for the harbour and the archipelago illustrates our approach to the interpretation of vertical and spatial trends, the need for normalisation and the advantage of integrating interpretations from several parameters. Geochemical relationships were investigated using multi-parameter normalisation. Significant time-dependent changes in the geochemical properties of the harbour sediments were also documented over a two-year period, highlighting the need for routine geochemical surveys to be conducted immediately prior to dredging operations.

Bergen Harbour:
Bergen Harbour is highly polluted and until 1999 received untreated sewage from more than 100,000 households and from industry. Within Bergen a detailed geochemical archive has been produced for the harbour with vertical and spatial trends investigated. There is a strong correlation between organic matter content and metal concentrations, but of even greater importance is the history of pollution discharge and how it has governed to accumulation. The study in this harbour has provided recommendation policies for the treatment of contaminated sediments. These deposits in parts of the harbour represent potential contaminant sources, which may become increasingly significant with further change in the harbour geometry and use.

Ventspils Harbour
Metal concentrations within Ventspils Harbour are generally low but require documentation since this harbour is undergoing a major phase of expansion, raising concerns for future pollution problems. A detailed geochemical archive has been produced for sediments in both the vertical and spatial context. Both total metal contents and mobility were examined using sequential extraction techniques. Geochemical relationships were also investigated using multi-parameter normalisation. The Venta River sediments are believed to be the main source of contaminants. It is therefore of considerable importance to determine the transport pathways and mixing of this material with the coarser, sandy sediments supplied from the coast.


Workpackage 3: Modelling and Applications.

The aim of workpackage 3 is to develop a predictive sedimentological model for the management of harbour activities with regard to silting and the evaluation of environmental pollution. Three modelling approaches have been applied to the spatial prediction of clay distribution, harbour bed conditions, Zn pollution and thickness of the recent sediment layer within a single harbour (Göteborg). The relative strengths and weaknesses of the three modelling alternatives are assessed. The Weighted Factors in Linear Combination and the Dempster-Shafer approaches use heuristic judgement (i.e. expert systems) in the prediction whereas the Artificial Neural Network (ANN) approach makes its prediction without using human bias. These models are a first generation development therefore, further steps are required before these tools can be used as a cost effective and justified methodology. One of the best avenues for further development would require a network of sedimentologists, modellers and practitioners.

Funding Scheme

CSC - Cost-sharing contracts

Coordinator

UNIVERSITY OF GOETEBORG
Address
Guldhedsgatan, 5A
4530 Goeteborg
Sweden

Participants (9)

IMPERIAL COLLEGE OF SCIENCE, TECHNOLOGY AND MEDECINE
United Kingdom
Address
Imperial College Road,
SW7 2BU London
Nottingham Trent University
United Kingdom
Address
Burton Street
NG1 4BU Nottingham
PORT OF GOETEBORG AB
Sweden
Address
Gate 5
40338 Goeteborg
SOGN OF FJORDANE COLLEGE
Norway
Address
Pobox 133
5801 Sogndal
STATE GEOGICAL SURVEY OF LATVIA
Latvia
Address
Eksporta Street, 5
1010 Riga
SWEDISH GEOTECHNICAL INSTITUTE
Sweden
Address
Chalmers Vasa, House 5
412 96 Göteborg
TECHNISCHE UNIVERSITEIT DELFT
Netherlands
Address
Thijsseweg 11
2629 JA Delft
UNIVERSITY OF BERGEN
Norway
Address
Allégt., 41
5007 Bergen
UNIVERSITY OF LATVIA
Latvia
Address
Daugavgrivas Str., 6
1007 Riga