Title
Predicting Landscape Effects of Mississippi River Diversions on Soil Organic Carbon Sequestration
Document Type
Article
Publication Date
2017
Keywords
Barataia Basin, Breton Sound Basin, Sea-level rise, Sediment diversion, Soil organic carbon sequestration, Subsidence, Vertical accretion
Abstract
Large Mississippi River (MR) diversions (peak water flow >1416 m3/s and sediment loads >165 kg/s) have been proposed as part of a suite of coastal restoration projects and are expected to rehabilitate and rebuild wetlands to alleviate the significant historic wetland loss in coastal Louisiana. These coastal wetlands are undergoing increasing eustatic sea-level rise, land subsidence, climate change, and anthropogenic disturbances. However, the effect of MR diversions on wetland soil organic carbon (SOC)
sequestration in receiving basins remains unknown. The rate of SOC sequestration or carbon burial in wetlands is one of the variables used to assess the role of wetland soils in carbon cycling and also to construct wetland carbon budgets. In this study, we examined the effects of MR water and sediment diversions on landscape-scale SOC sequestration rates that were estimated from vertical accretion for the next 50 yr (2010–2060) under two environmental (moderate and less optimistic) scenarios. Our analyses were based on model simulations taken from the Wetland Morphology model developed for Louisiana’s 2012 Coastal Master Plan. The master plan modeled a “future-without-action” scenario as well as eight individual MR
diversion projects in two of the hydrologic basins (Barataria and Breton Sound). We examined the effects that discharge rates (peak flow) and locations of these individual diversion projects had on SOC sequestration rates. Modeling results indicate that large river diversions are capable of improving basin-wide SOC sequestration capacity (162–222 g C.m-2.yr-1) by up to 14% (30 g C.m-2.yr-1) in Louisiana deltaic wetlands compared to the future-without-action scenario, especially under the less optimistic scenario. When large river diversions are placed in the upper receiving basin, SOC sequestration rates are 3.7–10.5% higher (6–24 g C.m-2.yr-1) than when these structures are placed in the lower receiving basin. Modeling results also indicate that both diversion discharge and location have large effects on SOC sequestration in low-salinity (freshwater and intermediate marshes) as compared to high-salinity marshes (brackish and saline marshes).
Publication Title
Ecosphere
Volume
8
Issue
11
DOI
https://doi.org/10.1002/ecs2.1984
Required Publisher's Statement
Copyright:© 2017 Wang et al. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited
http://onlinelibrary.wiley.com/doi/10.1002/ecs2.1984/epdf
Recommended Citation
Wang, H., G. D. Steyer, B. R. Couvillion, H. J. Beck, J. M. Rybczyk, V. H. Rivera-Monroy, K. W. Krauss, and J. M. Visser. 2017. Predicting landscape effects of Mississippi River diversions on soil organic carbon sequestration. Ecosphere 8(11):e01984. 10.1002/ecs2.1984
Subjects - Topical (LCSH)
Wetland management--Louisiana; Water diversion--Mississippi River; Carbon sequestration--Louisiana--Mathematical models
Geographic Coverage
Louisiana; Mississippi River
Supplement 1
Wang_et_al-2017-Ecosphere.sup-2.pdf (220 kB)
Supplement 2
Genre/Form
articles
Type
Text
Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 International License.
Language
English
Format
application/pdf
