S2S (Source-to-Sink)

Over-Arching Themes:

The Source-to-Sink initiative within MARGINS seeks to advance our predictive capability of sediment and solute fluxes and their fates on the Earth's continental margins. Improved predictions are necessary because this transfer plays a key role in the cycling of elements such as carbon in ecosystems impacted by climate change and sea-level rise, and in the resource management of soils, wetlands, groundwater, and hydrocarbons. At present we cannot anticipate how perturbations in one part of the source-to-sink system will affect another. A quantitative answer, clearly involving modeling, has practical as well as scientific justification. Would, for example, a 50% increase in sediment yield over the next century reverse coastal zone erosion, or would sediment be sequestered on floodplains, thereby increasing up-river flood risk? Would the increased sediment yields from a large earthquake in an upper watershed increase down-stream sedimentation (silting in, for example, shipping channels), and if so, over what duration? And what is the signature of such events in the stratal record?

The key scientific issues impeding better predictive capabilities for the source-to-sink system were identified at two MARGINS Source-to-Sink Workshops and a MARGINS Workshop convened to explore the concept of a Community Sediment Modeling Environment. The scientific issues are contained within three questions:

Question 1: How do tectonics, climate, sea level fluctuations, and other forcing parameters regulate the production, transfer, and storage of sediments and solutes from their sources to their sinks?

Question 2: What processes initiate erosion and sediment transfer, and how are these processes linked through feedbacks?

Question 3: How do variations in sediment processes and fluxes and longer term variations such as tectonics and sea level build the stratigraphic record to create a history of global change?

Methods of Studying S2S Processes:

Based on the workshops and considerable follow-up correspondence, community consensus agreed that S2S studies at selected sites should include:

  1. Assessment of available data and their suitability for building first-order computational and physical models;
  2. Field investigation of sediment production, transport and accumulation, and associated mechanics and rates;
  3. Second-order model building/testing to illuminate mechanisms of sediment transport and stratigraphy generation under various controls;
  4. Stratigraphic documentation at appropriate spatial resolution to provide desired temporal resolution;
  5. Monitoring and modeling of active processes are examples of work that should occur throughout the course of the proposed studies. For more detailed information about methods and new technologies, see the Science Plan pages 138 through 143.

Focus Sites:

(See Science Plans, page 143)

Critical Site Criteria:

Also desirable would be:

Source-to-Sink considered more than 20 sites, and selected two active convergent continental margins that produce large amounts of sediment deposited in adjacent, closed basins. Following community-wide discussions, the Fly River and adjacent Gulf of Papua (Papua New Guinea) and the Waipaoa River System on the east coast of New Zealand's North Island were chosen for focused research for the following reasons:

1. Fly River and adjacent Gulf of Papua (Papua New Guinea)

2. Waipaoa River System on the east coast of New Zealand's North Island

Workshops and Theoretical Earth Institutes (TEIs):

Funding for S2S Science has supported four organizational workshops, with a TEI anticipated for September, 2005). The past workshops were:

  1. S2S Organizational Meeting I. A four-day meeting organized by Neal Driscoll and Charles Nittrouer and funded by NSF and JOI was held at Lake Quinault, WA, on Sept 28-October 1, 1999 to create the S2S science plan.
  2. S2S Organizational Meeting II. A follow-up meeting was organized by Driscoll and Nittrouer at Lake Tahoe, on September 11-15, 2000, to gather more community input for the S2S science plan.
  3. S2S Community Sedimentary Model Science Plan. A two day workshop was organized by James Syvitski, et al., on February 20-22, 2002, to outline a strategy and protocol for constructing a community sediment model (CSM) as part of S2S.
  4. MARGINS Workshop On The Waipaoa Source-to-Sink Focus Area. A workshop for approximately 40 scientists was organized by Steve Kuehl, on May 4-9, 2003, to provide a synopsis of what is known about the system, what needs to be monitored, and to develop an implementation plan for research.

Major Research Activities - Funded Projects:

The following S2S research projects have been NSF funded to date (proposal start dates in parentheses) from MARGINS and MARGINS-related panels. They are all in the Papua New Guinea focus area because it was first organized:

Intellectual Progress During MARGINS:

Map (PDF) prepared by the MARGINS Office, showing the available information on where work has been funded to date in the Gulf of Papua focus area. (Click map for a larger version with explanatory caption.)

Map (PDF) prepared by the MARGINS Office, showing the available information on where work has been funded to date in the Waipaoa focus area. (Click map for a larger version with explanatory caption.)

Major Research Gaps:

Although much of the fieldwork for the Gulf of Papua project has only just begun, and MARGINS funding for the New Zealand project does not begin until FY 2005, we already can identify a number of future research needs:

Collaboration and Outreach:

Interdisciplinary scientific research in remote areas requires a broad range of collaborations. These have been forthcoming in both focus areas.

Papua New Guinea

The Gulf of Papua study, for example, involves collaboration with Drs. Robert Aller (SUNY, Stony Brook) and Miguel Goni (University of South Carolina), who are working, respectively, on the early diagenesis and carbon fluxes to the clinoform. We also have benefited greatly from previous and present collaboration with a number of Australian scientists, most notably Drs. Peter Harris (GeoScience, Hobart) and Gregg Brunskill (AIMS, Townsville).

At the same time, we have had an ever-increasing interaction with Papuan scientists and students. To date more than 20 have been on one or more legs of our various cruises, and several have spent periods of time in the United States. In at least one case a PNG scientist (Sioni Sioni, UPNG) will be a lead author on a talk presented at Fall AGU. Below is a list of Papua New Guineans who have participated in the program:

University of Papua New Guinea, Department of Geology:

Hugh Davies, Sioni Sioni, Russell Perembo, Marie Bera, Tina Apami, Jack Atomo, Don Bibaesi, Louisa Dira, Honoria Homu, Rellie Inia, Allan Ila, Alu Ila, Susan John, Magdaline Kepo, Fritz Koroba, Gabriel Laim, Paul Lale, Sarowaget Menggenang, Oala Rarua, Ora Renagi, Deveni Temu, and Ramsey Yehimen

Geological Survey of Papua New Guinea:

Jason Elemunop and James Mokepwesi

As part of the recent Gulf of Papua cruises, there were outreach broadcasts from the ship to a network of middle-school and junior-high school classrooms, in which students had the opportunity to ask scientists (including graduate students) a multitude of questions, ranging from scientific methods to career opportunities. In addition, there were several live broadcasts in which shipboard scientists talked directly with citizen groups around southern California.

New Zealand

Although MARGINS funding for the Waipaoa focus-site study has just begun, already there has been a fruitful collaboration between U.S. and New Zealand land-based and marine scientists. In contrast to Papua New Guinea, considerably more background data have been gathered by NZ researchers. More than 20 years of monitoring of the Waipaoa River by New Zealand scientists, for example, has given us a reasonably good understanding of annual and interannual cycles as well as some idea as to floodplain sedimentation. The Waipaoa 2003 planning workshop noted above included 40 scientists, roughly half each from the U.S. and NZ, including: geomorphologists, geologists, oceanographers, geochemists and hydrologists.

S2S Presentations and Publications:

(See “Research” section)

Nuggets:

(Proposal start dates in parentheses)

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