Regional Sediment Processes, Sediment Supply, and their Impact on the Louisiana Coast

Morang, Andrew; Rosati, Julie Dean; King, David B.

doi:10.2112/si63-013.1

Cited by 14 publications

(9 citation statements)

References 51 publications

(39 reference statements)

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“…Delta recession resulting from reduced riverine sediment supply has been observed in many places. The sediment delivery to coastal Louisiana has diminished by over 50% during the last 150 years and the delta can no longer grow as it once had due to urbanization and land reclamation (Morang et al ., ). In the Yangtze delta, riverine sediment discharge has declined by 15% from 1958 to 1978 to 1978–1997 and delta net accretion decreased from 38 mm yr −1 in 1958–1978 to 8 mm yr −1 in 1978–1997 (Yang et al ., ).…”

Section: Introductionmentioning

confidence: 97%

Conditional effects of tides and waves on short‐term marsh sedimentation dynamics

Ysebaert

Wal

et al. 2018

Earth Surf Processes Landf

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Salt marshes are in danger of degradation due to human impact and climate change. A thorough understanding of mechanisms controlling sedimentation and erosion in salt marshes is essential for their conservation and restoration. To understand short-term dynamics of sediment availability and deposition around marsh edges, two contrasting marshes, Rattekaai and Sint Annaland, were studied in the Oosterschelde (southwest Netherlands). Suspended sediment concentration (SSC) was measured by siphon samplers along four transects perpendicular to the marsh edge in each marsh, during nine flood tides between March and December 2013. Each transect was comprised of four sampling sites (À10 m and À1 m on the mudflat and +1 m and +10 m on the marsh plateau, relative to the marsh edge). Sediment deposition was measured along the transects on the marsh, at +1 m and +10 m from the marsh edge, over seven c. 14-day intervals during the same 10-month period. Two types of sediment traps were used, one measuring gross sediment deposition (TTDtube trap deposition) and one measuring net sediment deposition (FTDfilter trap deposition). Wave loggers were deployed 10 m away from the marsh edge on the mudflat at each marsh. The results showed that both SSC and sediment deposition varied greatly through space, both between the two marshes and within each marsh along the marsh edge. The SSC and gross sediment deposition were much higher at Rattekaai than at Sint Annaland. SSC was significantly correlated with wind speed during sampling. Sediment deposition rates (TTD and FTD) and retention ratio (FTD/TTD) were significantly correlated with cumulative wave energy during the measurement period. A conceptual model of local sediment dynamics is proposed to explain the sediment dynamics around the marsh edge. This study highlights the importance of incorporating local sediment dynamics when evaluating marsh vulnerability and stability.

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Section: Introductionmentioning

confidence: 97%

Conditional effects of tides and waves on short‐term marsh sedimentation dynamics

Ysebaert

Wal

et al. 2018

Earth Surf Processes Landf

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“…These brackish and salt marshes in Barataria Basin Louisiana are dominated by Spartina patens and Spartina alterniflora , respectively (Conner & Day, 1987). Barataria Basin is a diurnal micro‐tidal system (Georgiou et al., 2005). The soils in the study sites belong to Histosols order.…”

Section: Methodsmentioning

confidence: 99%

Temporal variability in soil organic matter accretion rates in coastal deltaic wetlands under changing depositional environments

White

Maiti

Inglett

et al. 2023

Soil Science Soc of Amer J

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The Mississippi River Deltaic Plain experiences high relative sea level rise, limited sediment supply, and high marsh edge erosion, leading to the substantial coastal wetland and stored soil organic matter (SOM) loss. The objective of this study was to understand the SOM accumulation rates over the past 1000 years related to the changes in the depositional environment in these highly eroding coastal wetlands.Soil cores (2 m) were collected from four sites in Barataria Basin, LA and analyzed for proportion of organic and mineral matter, total C, N, P, particle size, and stable isotopic composition (δ 13 C and δ 15 N), as well as 14 C and 137 Cs dating. The soil carbon stock in the 2 m depth (62.4 ± 2 kg m −2 ) was approximately 88% greater than the carbon stock in just the 1 m depth (33.1 ± 0.6 kg m −2 ) indicating a need for considering deeper soil profiles (up to 2 m) to estimate blue carbon stock in deltaic environments. The average vertical accretion rate for Barataria Basin was 8.1 ± 0.6 mm year −1 over 50 years. The long-term (1000-year time scale) C accumulation rate (39 g C m −2 year −1 ) was ∼14% of the short-term accumulation rate (254 ± 19 g C m −2 year −1 ). Wetlands in Barataria Basin started as fresh marsh and transitioned over time to intermediate to brackish. These marshes were able to maintain relative elevation through the accumulation of organic matter and mud despite high relative rates of sea-level rise. However, the high rates of edge erosion may limit these marshes to continue to sequester atmospheric carbon under accelerating sea level in the absence of restoration efforts. 1 2 METHODS Study site and erosion measurementThis study was conducted in the northern part of Barataria Bay in southeastern Louisiana (Figure 1). Coastal Louisiana marshes are facing relatively high rates of land loss in the Con-

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“…Coastal deltaic wetlands are among the most productive ecosystems worldwide that provide important environmental, economic, and societal value (Morang et al 2013;Moritsch et al 2022). Despite their immense value and resilience, deltaic systems around the world have experienced some of the highest rates of wetland loss (Törnqvist et al 2020) due to long-term modi cations in hydrology (Reyes et al 2000; Elsey-Quirk et al…”

Section: Introductionmentioning

confidence: 99%

Biomass and carbon stocks in deltaic wetlands across active and inactive basins in the Mississippi River Delta, USA

Solohin

Castañeda‐Moya

Twilley

et al. 2023

Preprint

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Deltaic wetlands in coastal Louisiana are experiencing widespread changes in vegetation dynamics and distribution due to rising sea level and long-term modifications in hydrology and sediment supply. Using field and remote sensing data, we investigated how aboveground biomass (AGB) and C stocks change in response to seasonality along salinity and soil nutrient gradients across different wetland habitats in two coastal basins with active (Atchafalaya - AB) and inactive (Terrebonne - TB) hydrological regimes. The highest seasonal changes in AGB and C stocks across both basins occurred in saline (SL) sites (AGB range: 343 ± 101 to 1214 ± 210 g m− 2) in early growing and peak biomass season, respectively. Biomass productivity rates varied across basins, with SL sites being the most productive, albeit less species-diverse. Foliar nutrient uptake was higher in the mineral-rich soils of AB freshwater (FW) site. In contrast, Terrebonne FW plants (as well as brackish and SL) had lower tissue nutrients and higher biomass allocation, indicating greater nutrient use efficiency with increasing salinity stress. Seasonal variation in AGB was positively correlated with porewater salinity and with soil nutrients (total nitrogen (N) and phosphorus). As hypothesized, changes in plant and soil isotopic signatures in both basins paralleled the spatiotemporal patterns in environmental stressors (e.g., elevated salinity and nutrient availability). Our findings show that in both active and inactive coastal delta basins, herbaceous wetlands maintain high biomass and C stocks by developing adaptive strategies in response to the distribution of environmental stressors and availability of resources.

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Regional Sediment Processes, Sediment Supply, and their Impact on the Louisiana Coast

Cited by 14 publications

References 51 publications

Conditional effects of tides and waves on short‐term marsh sedimentation dynamics

Conditional effects of tides and waves on short‐term marsh sedimentation dynamics

Temporal variability in soil organic matter accretion rates in coastal deltaic wetlands under changing depositional environments

Biomass and carbon stocks in deltaic wetlands across active and inactive basins in the Mississippi River Delta, USA

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