Leaky Deltas Webinars & Workshop

Scoping Workshop: Leaky deltas: sources or sinks in the global carbon cycle?


March 17-20, 2025
Louisiana State Univ. (Baton Rouge, LA)

Webinar Series

April 18: Bin Zhao and Thomas Bianchi - recording coming soon

March 14: Biogeochemical dynamics in deltaic sediments: The importance of the organic matter origin and event-driven variability -  Christophe Rabouille (Laboratoire des Sciences du Climat et de l'Environnement) --> watch the recording on YouTube

Did you attend the March 14 talk? Please give your feedback here. Includes question about workshop dates!

River deltas and the adjacent coastal ocean are critical interfaces between terrestrial and oceanic environments. Deltas are the entry point of ~50% of the fresh water and 40% of all global particulate matter entering the ocean. They are major centers for particulate and dissolved organic carbon net transfer from land to ocean.

Recent evidence suggests that coastal oceans have become net sink for atmospheric CO2 during post-industrial times and continued human pressures in coastal zones and alterations to deltas will likely have an important impact on the future evolution of the coastal ocean’s carbon budget.

Despite the importance of deltas and blue carbon ecosystems to the global carbon cycle and coastal communities, land-to-ocean parameterizations in Earth System models are highly simplified and do not mechanistically include many of the processes involved in cycling carbon in these areas.

Significant and critical knowledge gaps on processes, their impacts on marine biogeochemistry, and the direction of future change exist—this workshop aims to address those knowledge gaps.

We will bring together a diverse group who are committed to exploring the physical, temporal, and biogeochemical processes that modulate fluxes of carbon to and from global deltas. We will bolster community engagement and participation, with a particular emphasis on inclusion of minoritized populations, international partners, and state and federal U.S agencies through targeted activities, before, during, and after the workshop.

This scoping workshop will utilize momentum from the OCB 2023 Summer Workshop plenary session focused on deltaic systems to build a network of modelers, experimentalists, and field scientists working on deltas in this era of unprecedented climate change and other anthropogenic stresses, and will address and advance several OCB mission-specific topics:

  1. human and climate-driven changes in ocean biogeochemistry and related marine ecosystem impacts
  2. carbon cycling, storage, uptake, and modulation at a critical land-ocean interface along the aquatic continuum
  3. sedimentary fluxes and benthic-pelagic coupling as they relate to C, nutrients, and other elemental cycles e.g., O2, Fe, Mn
  4. marine organism response to environmental changes associated with delta loss, subsidence, salinization, and other anthropogenic disturbances
  5. promotion of minoritized shareholders in inclusive and equitable scientific discussions of unprecedented impacts of human-driven changes to deltaic systems.

Read the full activity proposal

Dive in to the science

OCB2023 PLENARY SESSION TALKS (recorded June 2023)

Role of deltaic sediments in regulating biogeochemical cycles (Chairs: Shaily Rahman, Jessica Luo, Cristina Schultz)

  • Introduction and OCB Benthic Ecosystem & Carbon Synthesis (BECS) working group highlight (Shaily Rahman, CU Boulder; Jessica Luo, NOAA/GFDL, Cristina Schultz, Northeastern Univ.)
  • Deltas as dynamic diagenetic and biogeochemical cycling systems (Robert Aller, Stony Brook Univ.)
  • Global river deltas and their relevance within Earth’s sediment source to sink (Jaap Nienhuis, Utrecht Univ.)
  • Distributary channel dynamics control water and sediment dispersal along deltaic coastlines (Brandee Carlson, Univ. Houston) (virtual)
  • Tools for interrogating deltas (Elizabeth Chamberlain, Wageningen Univ.)
  • Sea level and river deltas across time scales: From the last lowstand to modern anthropogenic alterations (Till Hanebuth, Coastal Carolina Univ.)
  • Oxygen and carbon dynamics in river-influenced shelf sediments (Kanchan Maiti, Louisiana State Univ.)
  • The biogeochemical cycling of Si and P in deltaic systems (Shaily Rahman, CU Boulder)
  • A mouth(ful) of mangroves taking root in tropical deltas (David Lagomasino, East Carolina Univ.)
  • Panel discussion

Ocean biogeochemistry – Influence of delta systems on adjacent coastal ocean in terms of carbon cycle (DIC/ALK/pCO2) both in water column and sediment, carbon burial and lateral transport of carbon.

Ecosystems – Role of salt marshes, mangroves, and sea grass on carbon retention and burial in delta plain and net export to adjacent ocean; reconstructions and forecasts of the distribution of these coastal ecosystems.

Novel methods and integration – Employing new technologies, e.g., chronology, remote sensing, to reconstruct and monitor delta change; integrating field and model data to study processes and change across timescales (past, present, and future).

Connectivity – Variability in hydrological connectivity across delta plain and delta shelf and its impact on carbon consumption, transport and retention.

Perturbations – Impact of climate and human driven changes including extreme events on delta carbon cycling.

Biogeochemical modeling: including mechanistic understanding of carbon cycling in the land-to-ocean continuum in global models, parameterizations of blue carbon ecosystems in high-resolution ocean models, quantifying organic and inorganic carbon transfers from deltas to theocean.

Community consensus Topic #1 and Topic # 2 – TBD



  • Recruit and build a community from an interdisciplinary group including geomorphologists, modelers, biogeochemists, paleoclimatologists, scientists with expertise in remote sensing technologies, scientists who integrate data across spatial-temporal scales, and of varying career stage, to study delta dynamics and associated impacts to marine C fluxes.
  • Compile and prioritize unresolved scientific questions or problems in the coupling between delta dynamics and marine C fluxes.
  • Engage with and query community to begin achieving community consensus.


  1. Remote townhalls
  2. Sessions at Goldschmidt 2024 and AGU 2024
  3. Gatherings with NASA DeltaX, CMS (Carbon Monitoring System), and CSDMS (Community Surface Dynamics Modeling System) communities at their annual meetings
  4. Electronic surveys sent to townhall participants and session attendees (with their permission) to determine several community-consensus-driven topics to be highlighted in the 3-day scoping workshop

In the pre-workshop activities we will invite speakers from different continents and include in our discussions the different location-based needs from different communities (global representation). We will offer support on presentation delivery, design, and practice sessions to non-native English and early-career speakers before the actual online events, as a form of professional development.


The workshop aims to develop knowledge and define future research needs on the role of deltas in the global carbon cycle—while building an interdisciplinary community (with a focus on ECR and underrepresented minoritized scientists)—around this understudied yet critical aspect of ocean biochemistry. To distribute these outcomes to the broader community there will be a consensus paper, a global delta carbon budget infographic, and an AGU Eos piece.


DAY 0: Arrival, check-in, poster set-up

Evening mixer: Welcome attendees, brief workshop introduction, goals, expectations, code of conduct
Morningbreakfast providedAfternoon - lunch providedEvening
DAY 1Welcome & open the workshop
Lightning Talks
Breakout groups (identifying unresolved scientific

Report out + discussion

Excursion to the LSU Center for River Studies (build comradery & gain inspiration)
Dinner and networking reception

Lightning Talks

Poster session
2 Breakout/working groups (assigned)
to consider knowledge gaps identified on Day 1

Report out + discussion
Dinner in groups –self organize
DAY 31 Plenary

Breakout groups: work
on identified deliverables
Breakout groups work on deliverables

Breakout groups: brainstorm ways to increase community participation

Evaluate: was community consensus achieved during the workshop?

Adjourn ~4PM


Shaily Rahman (UC Boulder)
Kanchan Maiti (LSU)
Jaap Nienhuis (Utrecht University)
Cristina Schultz (Northeastern University)
Elizabeth Chamberlain (Wageningen University)
Julia Moriarty (CU Boulder)
Marisa Repasch (University of New Mexico)