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The Australian Coastal Zone and Global Change: Research Needs

Australian Academy of Science, Becker House, Canberra. Friday 16 December 1994

Tropical river/ocean processes in coastal settings (tropics)

Dr Gregg Brunskill

Project TROPICS is the concept that exists in about 30 research scientists' minds and on some joint publications. At the moment it is a loose consortium of researchers who work in the wet tropics. The main issue to be resolved is how sediments and solvents are delivered to continental shelves in the extreme wet tropics with 10 to 12 metres of rain per year and gigantic inputs of fresh water into coastal zones that are very narrow and very wide.

The wet tropics is a relatively small part of the global surface area but supplies a huge amount of fresh water and sediments to the world ocean. The group of people that I am representing includes Charles Nittrouer and a group of people who had worked for 10 years on the Amazon coastal shelf. This group, largely intact, is publishing the last part of their work and they are joining a group of people from Australia who are interested in studying the continental shelves, essentially the entire coastal shelf of the island of New Guinea: Irian Jaya and Papua New Guinea (see Attachment 1).

The goal is to understand mechanisms and establish models of coastal ocean trapping, bypassing, and cycling of solutes and sediments from a wet tropical area of high relief (PNG & Irian Jaya) on contrasting coastal shelves. We will determine the processes that control the dispersal of wet tropical riverine dissolved and particulate material into the coastal ocean, and how these processes affect estuarine, deltaic, coastal, shelf & slope productivity, marine resources, and sustainable development options.

Due to high precipitation, great relief, and tectonically active geography, the island of New Guinea (Irian Jaya & Papua New Guinea) contributes more water, solutes, and sediment to the coastal ocean than the Amazon River. The north coast of PNG & Irian Jaya delivers riverine material directly to deep waters of the Bismarck Sea, with little or no estuarine or coastal shelf environment. We choose to study the Sepik and/or the Mamberamo River estuaries & coastal ocean plumes in this region. In contrast, the rivers of the west coast of Irian Jaya drain the same mountain ranges, but discharge into broad swampy alluvial plains, long estuaries, and a broad, shallow continental shelf. We choose to study the Digul River estuary and coastal shelf plume in the Arafura Sea. The south coast of PNG, including the rivers from the Fly eastward to the Purari, discharge through large deltaic and estuarine systems in to a narrowing continental shelf with sharp boundaries between riverine muds and clean marine carbonate sediments.

The research objectives of the biological group, the chemical group, the physical oceanographic group and geological groups are detailed separately (see Attachment 2). Researchers at AIMS and the University of Sydney, Peter Harris and a group of us have been working in the Fly delta and in the Gulf of Papua for the past 12 years. The Fly River delta discharges large amounts of sediment water into the northern Torres Strait and the Gulf of Papua. Bramble Cay, which I will be talking about later on, has big pyrites corals that probably record the history of flow. My colleagues, Alastair Robertson and Dan Alongi, have done extensive work on mangrove primary production, growth rates, respiration. My job with the team was to try to estimate the storage of materials in the sediments in the Fly delta. We have produced an organic carbon budget for this region.

My colleague, Eric Wolanski, has done extensive hydrodynamic modelling in the estuary and in the Gulf of Papua as well, indicating a very lengthy trapping of particulate material in the delta front region, as is found in other parts of the world. My job is focused on how sediment stores or retains material that does not reach the deep sea ocean. I am trying to figure out what is retained in these different zones of the estuary and on the continental shelf.

The Castan corer that has been used from 10 metres water depth out to about 2500 metres in the Gulf of Papua. The Castan corer has shown us that there are many locations that have laminations in the cores. Some of the laminations might even be annual. The combined discharge of the Fly and the Purari Rivers, for example, is greater than the run-off for the whole continent of Australia.

The aluminal silicate terrestrial materials are along the coast. Immediately off the mouth of these rivers is a very clean carbonate platform that has little or no terrestrial material at all. Terrestrial materials from these rivers move along the coast and may actually enter in the deeper water column towards Port Moresby. What we would like to do is try to export these methods and techniques to the Digul, Mamberamo and Sepik regions of New Guinea that have very different kinds of coastline.

That kind of a study is important globally it is not a regional study. This is a globally important study because this is the location of by far the largest sediment inputs to the world ocean, far larger than that from the Amazon, for example, where much more water is contributed. This region of the Indonesian archipelago in the wet tropics is the major source of sediment transport.

Riverine effects can be seen better by fore-fringing coastal reefs by looking at fluorescence in the annual bands. Peter Isdale at AIMS has used this technique and hindcast a discharge of rivers with considerable accuracy for the known discharge record. Using these corals, we can hindcast river discharge, at least flood discharge, back approximately four centuries.

This kind of information is of global importance, not regional importance, because we are talking about a region in the world where there is between 10 and 12 metres of precipitation per year, a very large run-off of water from the island of New Guinea. It is also in the path of the Indonesian throughflow. The physical oceanographers, desire to assemble as many tracers of Pacific water going through the Indonesian archipelago chain as possible. One of our objectives is to try to provide that by studying the estuarine and riverine run-off into this region of the world ocean.

It is also of global importance to have a study in this region primarily because of the association with the most warm part of the whole world ocean, a little patch of water to the north of New Guinea. Under normal conditions this region has a very hot water pool between 29 and 30 degrees. In other El Niņo years this pool moves eastward and causes havoc to parts of Australia and much of the rest of the world.

Without going into detail Project TROPICS will contribute to foci 1, 2 and 3 of LOICZ with emphasis upon the physical and chemical aspects of things. We are highly focused towards the coastal zone not in deep water. We do not intend to become involved in large amounts of biological research.

The members of Project TROPICS who are now trying to work out research agreements and attach them to memorandums of understanding in order to enable our research ships to enter Indonesian and Papua New Guinean waters is provided as an attachment. This list of personnel who are involved in this is very large. The main information is that it includes a large number of research laboratories, some which have lots of money and some of which do not. We are trying to get enough money for the Australian group itself to fund ships and some special oceanographic equipment to put on the ships. Most of the actual science operations will have to be provided by the host laboratories.

We are trying to find enough base money to fund the Franklin for cruises in 1997 and 1999 and probably to have a couple of gadgets that we use to estimate sediment transport and work in the Delta Drilling Rig Program.

fig 1: map of the island of New Guinea

Overhead 1

Attachment 2


  1. The biological group will quantify & model the differences in the production & decomposition of organic matter in the water column seabed at these very different coastal sites. They will quantify how biological processes & communities are affected by sediment-water exchanges, and how terrestrial and marine organic matter is decomposed or preserved in the sediments. This work will be used to construct models of how the coupling between coastal benthic & pelagic regimes influence productivity of mangroves, prawns, finfish, and marine mammal harvestible resources in these contrasting wet tropical sites.
  1. The chemical group will quantify and model the reactions of rapidly transported weathering products from these similar river basins to very different estuary and shelf environments, including the release and uptake of nutrients, trace elements, and organic biomarkers. There is extremely high annual loading of suspended sediments in these estuaries coastal zones, and we will determine the estuarine shelf "trapping efficiency" for dissolved & particulate elements. For the same reasons, we expect to see spectacular scavenging of oceanic elements in some of these particle-rich coastal zones. We will determine the recent (Holocene) history of coastal geochemical processes from sediment and coral cores. Chemical tracers for the Indonesian ThroughQow & Equatorial Undercurrent will be sought.
  1. The physical oceanographic group will quantify & model the variations in physical structure & processes that control the trapping & cycling of riverine & oceanic elements in contrasting narrow and wide continental shelves. We will describe & model the roles of flocculation, tidal pumping, waves, 3dimensional estuarine structure & circulation, multiple riverine sources, and fronts in particle trapping. We plan to determune how bottom stress from currents & waves inQuences grain-size distribution in surficial sediment- and suspended sediment, and what processes lead to patchiness of river plumes and bottom sediments. We want to study the roles of surface and internal waves as a forcing function in water mass mixing and river plume dynamics, and how this regional mixing circulation affects near& far-field flow. These forces control the coastal dispersal of dissolved particulate riverine material.
  1. The geological group will study Holocene contrasts between foreland & leading-edge margin sedimentation, with emphasis on sediment partitioning between the estuaries, shelves, slopes, the deep sea. Of particular interest will be the special aspects of continental-margin sediment dispersal from distributed sources (multiple large riverine inputs) to very different continental-margin bathymetries. Present gradients from riverine clastic sediments to marine carbonate sediment zones will be used to interpret the history of variations of these sediment types in cores, which represent changes in runoff, sediment stability, and dispersal paths. The north coast of New Guinea is an analog for all rivers in understanding sediment dispersal during low sea-level stands previous to 6000 years ago.


We will need land-based teams of investigators, for estimations of riverine discharge of water, dissolved materials, and sediments, and coring operations to discover the recent history of sedimentation in alluvial valleys, deltas, and mangrove swamps. We will need to have historical climatic data for each river basin, and some knowledge of changes in land use and population.

At sea we will use standard oceanographic equipment on large and small vessels suitable for the coastal region. Short-(weeks) and long-term (months) deployments will be made for tide, current, wave, sediment, and chemical measurements. The use of specialized equipment for large volume water sampling, seafloor biological geochemical measurements (lander), and seafloor currents sediment resuspension is anticipated. Field operations are planned for 1997-2000.

All investigators will agree upon standardized methods for each region, and we will utilize a standard sampling grid for each region, to enable direct comparisons of results. The resulting database will be available to all collaborators. Type specimens reference collections will be made available to Indonesian & Papua New Guinean authorities. All research will be done with prior approval from and in collaboration with Indonesian PNG governments & scientific institutions.


Baseline environmental conditions in pristine areas Training, education, technology transfer in marine & terrestrial environmental science Coastal erosion, turbidity, sediment transport to regions of coral reefs Information on harbour siltation, seabed stability, sediment transport along shores Past history predictions of future climate sea-level changes Dispersal of nutrients to coastal & oceanic food chains Estimations of biological productivity in estuaries & coastal zone Documentation of importance of mangroves in trapping sediments & nutrients Pathways for contaminant transport in the coastal zone (hydrocarbons, metals) Assistance with river gauging stations, runoff sediment discharge Recent history of riverine transport of materials to the coastal zone Estimates of effecs of land-use change, development Contributions to global ocean chemical sedimentary budgets Information on how the coastal zone traps material from the ocean Identification of Indonesian Throughflow Equatorial Undercurrent tracers


Participating scientists and their institutions have a wide range of laboratory and field equipment for specialized coastal oceanography. These laboratories are listed in the next section. Research vessels from Australia, Indonesia, and USA are invited to participate. The core group of TROPICS has experience in coastal oceanography of the Great Barrier Reef, Gulf of Papua, the Torres Strait, the NW Shelf of Australia, the coastal zone of the Amazon River, as well as other non-tropical portions of the world.

We are seeking funding eC logistic assistance from international agencies, Australia, Indonesia, PNG, USA, and industry (mining, petroleum, timber). We welcome suggestions for cooperative research & funding.


As of July 1994, the core group consists of a steering committee, the TROPICS planning group, and a larger number of colleagues 8c laboratories around the world. For further information about TROPICS, please consult with any of the representatives listed below.


Dr. Gregg J. Brunskill
Australian Institute of Marine Science
PMB No. 3, Townsville, Queensland 4816, Australia
Fax 077 725 852, Internet G BRUNSKILL@AIMS.GOV.AU

Dr. Charles A. Nittrouer
Marine Sciences Research Center
State University of New York
Stony Brook, New York 11794-5000, USA
Fax 516 632 8820, Internet CNITTROUER@CCMAIL.SUNYSB.EDU

Mr. Gaikovina Kula
Department of Environment Conservation
PO Box 6601
Boroko, NCD, Papua New Guinea, Fax 675 271764

Dr. Anugerah Nontji
Centre for Research ec Development in Oceanology, LIPI
Jalan Pasir Putih 1, Ancol Timur
Jakarta Utara, Indonesia, Fax 62 21681948

Mr. Ian Wood
Ok Tedi Mining LTD
PO Box 1, Tabubil, Western Province
Papua New Guinea, Fax 67S 589 390

Drs. George Cresswell, Denis Mackey
Division of Oceanography
CSIRO, GPO Box 1538
Hobart, Tasmania 7001, Australia
Fax 002 325123


Dr. David DeMaster
Department of Mrine, Earth Atrnospheric Sciences
North Carolina State University
Raleigh, North Carolina 27697-8208, USA

Mr. Ron Szymczak, Dr. Henk Heijnis
Australian Nuclear Science Technology Organization
Lucas Heights Environmental Laboratories
PMB 1, Menai, NSW 2234, Australia
Fax 02 717 9260, Internet RSX@NUCLEUS ANSTO.GOV.AU
Fax 02 717 9270, Internet HHX@NUCLEUS.ANSTO.GOV.AU

Drs. Robert Josephine Aller
Marine Sciences Research Center
State University of New York
Stony Brook, New York 11794-5000, USA
Fax 516 632 8820, Internet: RALLER@CCMAL.SUNYSB.EDU

Drs. Dan Alongi, Eric Wolanski, Kathy Burns
Australian Institute of Marine Science
PMB No. 3, Townsville, Queensland 4810, Australia
Fax: 077 725 852

Drs. Rocky Geyer, Ed Sholkovilz
Woods Hole Oceanographic Institution
Woods Hole, Massachusetts 02543, USA
Fax: 508 548 6013, Internet ROCKY@GUSTY.WHOIEDU

Dr. Michael Bird
Research School of Earth Science
Australian National University
Canberra, ACT 0200, Australia
Fax 06 249 0738, Internet MICHAEL.BIRD@ANUEDU.AU

Drs. John Milliman, Don Wright, Steve Kuehl
Virginia Institute of Marine Science, College of William Mary
Gloucester Point, Virginia 23062-1346, USA
Fax 804 642 7250, Internet: ZEALON@VIMSEDU

Dr. Ken Woolfe
Department of Geology, Jarnes Cook University
Townsville, Queensland 4811, Australia
Fax 077 251501, Internet: KEN.WOOLFE@JCUEDU.AU

Dr. Keith Crook
Hawaii Undersea Research Laboratory, University of Hawaii
1000 Pope Road MSB 303-B
Honolulu, Hawaii 96822, USA
Fax 808 956 9772, Internet CROOK@KELA.SOEST.HAWAIIEDU

Drs. Graeme Batley, Simon Apte
Centre for Advanced Analytical Chemistry
CSIRO, PMB 7, Menai, NSW 2234
Fax 02 710 6837, Internet

Dr. J. David SmiLh
School of Chemistry
University of Melbourne
Parkville, Victoria 3052

Drs. Richard Sternberg, Glen Shen
School of OceanogIaphy, WB-10
University of Washington
Seaule, Washington 98195, USA
Fax 206 685 3354, Internet: RWS@WASINGTONEDU

Dr. Ron Gibbs
College of Marine Studies
University of Delaware
Newark, Delaware 19716, USA
Fax 302 8316838, Internet: GIBBS@BACH.UDELEDU