Blue carbon ecosystems (BCEs) are coastal ecosystems, such as tidal marshes, mangroves, and seagrasses, with manageable and atmospherically significant carbon stocks and fluxes. The tidal marshes and scrub-shrub wetlands in the Sacramento-San Joaquin Delta (Delta) of California are examples of BCEs. The Delta is a 2,400 square kilometer tidal freshwater region located at the landward end of the San Francisco Estuary. The area used to be an extensive peatland, but was mostly drained for agriculture in the late 1880s and early 1900s. Wetland restoration, which has been underway for some time, has the potential to expand important habitat for biodiversity and mitigate land-surface subsidence and carbon loss that has occurred subsequent to drainage.

The ability of wetlands in different areas of the Delta to store carbon, build elevation, and halt land-surface subsidence is not well understood. This has hindered scientists and managers from optimizing wetland restoration to maximize ecological and societal benefits. This project seeks to address this knowledge gap by combining data on peat formation processes through time, digital elevation models, and marsh accretion and subsidence modeling to better understand the historical and current Delta carbon sink and the future sustainability of tidal wetlands in the region.
Objective
The main objectives of this project are to quantify carbon storage and greenhouse gas emissions in the Delta region and estimate the future sustainability of tidal wetlands under sea-level rise.
Science Plan
This project is a collaboration between the USGS, the San Francisco Estuary Institute (SFEI), and Hydrofocus, Inc. There are two main tasks. In task 1, the USGS is working with SFEI and Hydrofocus, Inc. to estimate the current carbon sink and future carbon storage under different scenarios. In task 2, the USGS is working with Dr. James Morris of the University of South Carolina and SFEI to use the Coastal Wetland Equilibrium Model (CWEM) to project the future sustainability of tidal marshes in the Delta region.
Relevance and Benefits
This project addresses the Strategic Directions for U.S. Geological Survey Water Science, 2012– 2022, to predict changes in the quantity and quality of water resources in response to changing climate, population, land-use, and management scenarios. Both tasks of the project are strongly related to wetland sustainability under changing watershed conditions due to climate change, sea-level rise, and changing management scenarios.
With regard to regional science needs, this project addresses the following Science Action Areas of the Delta Science Program: (2) coordinating and integrating Delta science in a transparent manner, (3) enabling and promoting science synthesis, and (5) supporting effective adaptive management.
Timeline and Outcomes
Work on this project began in the spring of 2020. Final products are expected in the fall of 2022.
Below are other science projects associated with this project.
NASA-USGS National Blue Carbon Monitoring System
Below are publications associated with this project.
An assessment of future tidal marsh resilience in the San Francisco Estuary through modeling and quantifiable metrics of sustainability
Modeling tidal freshwater marsh sustainability in the Sacramento-San Joaquin Delta under a broad suite of potential future scenarios
Adjustment of the San Francisco estuary and watershed to decreasing sediment supply in the 20th century
Peat formation processes through the millennia in tidal marshes of the Sacramento-San Joaquin Delta, California, USA
Peat accretion histories during the past 6,000 years in the marshes of the Sacramento-San Joaquin Delta, CA, USA
The legacy of wetland drainage on the remaining peat in the Sacramento-San Joaquin Delta, California, USA
Below are partners associated with this project.
- Overview
Blue carbon ecosystems (BCEs) are coastal ecosystems, such as tidal marshes, mangroves, and seagrasses, with manageable and atmospherically significant carbon stocks and fluxes. The tidal marshes and scrub-shrub wetlands in the Sacramento-San Joaquin Delta (Delta) of California are examples of BCEs. The Delta is a 2,400 square kilometer tidal freshwater region located at the landward end of the San Francisco Estuary. The area used to be an extensive peatland, but was mostly drained for agriculture in the late 1880s and early 1900s. Wetland restoration, which has been underway for some time, has the potential to expand important habitat for biodiversity and mitigate land-surface subsidence and carbon loss that has occurred subsequent to drainage.
Sources/Usage: Some content may have restrictions. Visit Media to see details.The Sacramento-San Joaquin Delta The ability of wetlands in different areas of the Delta to store carbon, build elevation, and halt land-surface subsidence is not well understood. This has hindered scientists and managers from optimizing wetland restoration to maximize ecological and societal benefits. This project seeks to address this knowledge gap by combining data on peat formation processes through time, digital elevation models, and marsh accretion and subsidence modeling to better understand the historical and current Delta carbon sink and the future sustainability of tidal wetlands in the region.
Objective
The main objectives of this project are to quantify carbon storage and greenhouse gas emissions in the Delta region and estimate the future sustainability of tidal wetlands under sea-level rise.
Science Plan
This project is a collaboration between the USGS, the San Francisco Estuary Institute (SFEI), and Hydrofocus, Inc. There are two main tasks. In task 1, the USGS is working with SFEI and Hydrofocus, Inc. to estimate the current carbon sink and future carbon storage under different scenarios. In task 2, the USGS is working with Dr. James Morris of the University of South Carolina and SFEI to use the Coastal Wetland Equilibrium Model (CWEM) to project the future sustainability of tidal marshes in the Delta region.
Delta wetland near Rio Vista, California. Relevance and Benefits
This project addresses the Strategic Directions for U.S. Geological Survey Water Science, 2012– 2022, to predict changes in the quantity and quality of water resources in response to changing climate, population, land-use, and management scenarios. Both tasks of the project are strongly related to wetland sustainability under changing watershed conditions due to climate change, sea-level rise, and changing management scenarios.
With regard to regional science needs, this project addresses the following Science Action Areas of the Delta Science Program: (2) coordinating and integrating Delta science in a transparent manner, (3) enabling and promoting science synthesis, and (5) supporting effective adaptive management.
Timeline and Outcomes
Work on this project began in the spring of 2020. Final products are expected in the fall of 2022.
- Science
Below are other science projects associated with this project.
NASA-USGS National Blue Carbon Monitoring System
The NASA-USGS National Blue Carbon Monitoring System project will evaluate the relative uncertainty of iterative modeling approaches to estimate coastal wetland (marsh and mangrove) C stocks and fluxes based on changes in wetland distributions, using nationally available datasets (Landsat) and as well as finer scale satellite and field derived data in six sentinel sites. - Publications
Below are publications associated with this project.
An assessment of future tidal marsh resilience in the San Francisco Estuary through modeling and quantifiable metrics of sustainability
Quantitative, broadly applicable metrics of resilience are needed to effectively manage tidal marshes into the future. Here we quantified three metrics of temporal marsh resilience: time to marsh drowning, time to marsh tipping point, and the probability of a regime shift, defined as the conditional probability of a transition to an alternative super-optimal, suboptimal, or drowned state. We usedModeling tidal freshwater marsh sustainability in the Sacramento-San Joaquin Delta under a broad suite of potential future scenarios
In this paper, we report on the adaptation and application of a one-dimensional marsh surface elevation model, the Wetland Accretion Rate Model of Ecosystem Resilience (WARMER), to explore the conditions that lead to sustainable tidal freshwater marshes in the Sacramento–San Joaquin Delta. We defined marsh accretion parameters to encapsulate the range of observed values over historic and modern tiAdjustment of the San Francisco estuary and watershed to decreasing sediment supply in the 20th century
The general progression of human land use is an initial disturbance (e.g., deforestation, mining, agricultural expansion, overgrazing, and urbanization) that creates a sediment pulse to an estuary followed by dams that reduce sediment supply. We present a conceptual model of the effects of increasing followed by decreasing sediment supply that includes four sequential regimes, which propagate downPeat formation processes through the millennia in tidal marshes of the Sacramento-San Joaquin Delta, California, USA
The purpose of this study was to determine peat formation processes throughout the millennia in four tidal marshes in the Sacramento-San Joaquin Delta. Peat cores collected at each site were analyzed for bulk density, loss on ignition, and percent organic carbon. Core data and spline fit age-depth models were used to estimate inorganic sedimentation, organic accumulation, and carbon sequestrationPeat accretion histories during the past 6,000 years in the marshes of the Sacramento-San Joaquin Delta, CA, USA
The purpose of this study was to determine how vertical accretion rates in marshes vary through the millennia. Peat cores were collected in remnant and drained marshes in the Sacramento–San Joaquin Delta of California. Cubic smooth spline regression models were used to construct age–depth models and accretion histories for three remnant marshes. Estimated vertical accretion rates at these sites raThe legacy of wetland drainage on the remaining peat in the Sacramento-San Joaquin Delta, California, USA
Throughout the world, many extensive wetlands, such as the Sacramento-San Joaquin Delta of California (hereafter, the Delta), have been drained for agriculture, resulting in land-surface subsidence of peat soils. The purpose of this project was to study the in situ effects of wetland drainage on the remaining peat in the Delta. Peat cores were retrieved from four drained, farmed islands and four r - Partners
Below are partners associated with this project.