Influence of the Wax Lake Delta sediment diversion on aboveground plant productivity and carbon storage in deltaic island and mainland coastal marshes

DeLaune, Ronald D.; Sasser, Charles E.; Evers-Hebert, E.; White, John R.; Roberts, Harry H.

doi:10.1016/j.ecss.2016.05.010

Cited by 35 publications

(9 citation statements)

References 31 publications

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“…Nevertheless, our analysis showed a significant interaction between denitrification rates and the type of wetland habitat in each region. This might be due to differences in sediment deposition dynamics, substrate age, and vegetation development stage (Carle & Sasser, 2016;DeLaune et al, 2016;Li et al, 2020).…”

Section: Differences In Denitrification As An Ecosystem Servicementioning

confidence: 99%

Emerging Wetlands From River Diversions Can Sustain High Denitrification Rates in a Coastal Delta

et al. 2021

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This biochemical transformation can be supported by nitrate diffusion and infiltration into sediment and soils from overlying water (i.e., direct denitrification NO 3 − →N 2 ) or by NO 3 − generated from nitrification within these substrates (coupled nitrification-denitrification: NH 4 + → NO 3 − →N 2 ). Because these N transformations can potentially ameliorate eutrophication (i.e., N enrichment) in inland and coastal waters (All dred & Baines, 2016;Mitsch et al., 2005), denitrification is considered a key ecosystem service in coastal zones that are often subjected to high N loads as a result of human impacts (

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Section: Differences In Denitrification As An Ecosystem Servicementioning

confidence: 99%

Emerging Wetlands From River Diversions Can Sustain High Denitrification Rates in a Coastal Delta

et al. 2021

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“…Due to its small size, relatively good historical record over the last several decades, and lack of substantial engineering [47], the WLD is an ideal place to study young delta dynamics at sub-decadal scales. The WLD has proven useful in previous geomorphological studies, such as on sediment diversion and marsh restoration potential [12,[51][52][53][54][55], (sub)aqueous sediment and channel dynamics and fluxes [56][57][58][59][60][61][62][63], river flood, hurricane, and cold front effects on marsh elevations [5,64,65], and delta sedimentation and lobe progradation [18,66]. The WLD has also yielded insights into delta hydrology, including on surface water residence and connectivity [67][68][69][70], surface water-groundwater interactions [31], and effects of river, floods, tides, wind, hurricanes, and cold fronts on water levels [4,5,31,50,64,65,71,72].…”

Section: Study Areamentioning

confidence: 99%

Short-Term Ecogeomorphic Evolution of a Fluvial Delta from Hindcasting Intertidal Marsh-Top Elevations (HIME)

Smith¹,

Moffett

Mohrig

2020

Remote Sensing

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Understanding how delta islands grow and change at contemporary, interannual timescales remains a key scientific goal and societal need, but the high-resolution, high frequency morphodynamic data that would be most useful for this are as yet logistically prohibitive. The recorded water levels needed for relative elevation analysis are also often lacking. This paper presents a new approach for hindcasting intertidal marsh-top elevations (HIME) to resolve ecogeomorphic change, even in a young, rapidly changing fluvial delta setting, at sub-decadal temporal resolution and at the spatial resolution of widely available optical remote sensing imagery (e.g., 30 m Landsat). The HIME method first calculates: (i) the probability of land exposure in a set of historical imagery from a user-defined discrete timespan (e.g., months or years); (ii) the probability of water level non-exceedance from water level records, which need not be complete nor coincident with the imagery; and (iii) the systematic variation in local mean water level with distance along the primary hydraulic gradient. The HIME method then combines these inputs to estimate a marsh-top elevation map for each historical timespan of interest. The method was developed, validated, applied, and results analyzed to investigate time-lapse evolution of the Wax Lake Delta in Louisiana, USA, every three years, over two decades (1993–2013). The hindcast maps of delta island extents and elevations evidenced ecogeomorphic system self-organization around four stable attractors, or elevation platforms, at about −0.3 m (subtidal), 0.2 m, 0.4 m, and 0.9 m (supratidal) NAVD88. The HIME results also yielded a time series of net subaerial sediment accumulation, and specific locations and magnitudes of gains and losses, at scales from 30 m to delta-wide (~100 km3) and 6 to 21 years. Average subaerial net sediment accumulation at the Wax Lake Delta (WLD) was estimated as 0.6 cm/yr during the study period. Finally, multiple linear regression models were successfully trained on the HIME elevation maps to model evolving delta island morphologies based on simple geometric factors, such as distance down-delta and position on a delta island; the models also successfully reproduced an average delta topset slope of 1.4 cm. Overall, this study’s development and application of the HIME method added detailed insights to recent, transient ecogeomorphological change at the WLD, and demonstrated the potential of the new approach for accurately reconstructing past intertidal topographies and dynamic change.

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“…This idea evolved from the river continuum concept [7], which describes the development of the structure and function of biotic communities along a longitudinal gradient in dynamic equilibrium with the physical environment [8]. The pulsing water-flow regime from river diversions supplies coastal wetlands with freshwater, sediments, and nutrients, enhancing productivity, vertical sediment accretion, and marsh stability [6,[9][10][11][12]. The first major freshwater diversion to begin operation in 1991 along the lower Mississippi is located at Caernarvon, LA, about 32 km south of New Orleans.…”

Section: Introductionmentioning

confidence: 99%

Benthic Nutrient Fluxes across Subtidal and Intertidal Habitats in Breton Sound in Response to River-Pulses of a Diversion in Mississippi River Delta

Twilley

Rick

Bond

et al. 2021

Water

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We measured benthic fluxes of dissolved nutrients in subtidal sediments and intertidal soils associated with river-pulse events from Mississippi River via the operation of a river diversion structure at Caernarvon, LA. Experiments measuring benthic fluxes in subtidal habitats were conducted during the early spring flood pulse (February and March) each year from 2002 to 2004, compared to benthic fluxes of intertidal habitats measured in February and March 2004. Nitrate (NO3−) uptake rates for subtidal sediments and intertidal soils depended on overlying water NO3− concentrations at near-, mid-, and far-field locations during river-pulse experiments when water temperatures were >13 °C (NO3− removal was limited below this temperature threshold). NO3− loading to upper Breton Sound was estimated for nine river-pulse events (January, February, and March in 2002, 2003, and 2004) and compared to NO3− removal estimated by the subtidal and intertidal habitats based on connectivity, area, and flux rates as a function of NO3− concentration and water temperature. Most NO3− removal was accomplished by intertidal habitats compared to subtidal habitats with the total NO3− reduction ranging from 8% to 31%, depending on water temperature and diversion discharge rates. River diversion operations have important ecosystem design considerations to reduce the negative effects of eutrophication in downstream coastal waters.

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Influence of the Wax Lake Delta sediment diversion on aboveground plant productivity and carbon storage in deltaic island and mainland coastal marshes

Cited by 35 publications

References 31 publications

Emerging Wetlands From River Diversions Can Sustain High Denitrification Rates in a Coastal Delta

Emerging Wetlands From River Diversions Can Sustain High Denitrification Rates in a Coastal Delta

Short-Term Ecogeomorphic Evolution of a Fluvial Delta from Hindcasting Intertidal Marsh-Top Elevations (HIME)

Benthic Nutrient Fluxes across Subtidal and Intertidal Habitats in Breton Sound in Response to River-Pulses of a Diversion in Mississippi River Delta

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