Effects of Impoundment on Vertical Accretion of Coastal Marsh

• Published in: Estuaries Vol. 21; no. 3; pp. 416 - 422
• Main Authors: Bryant, John C., Chabreck, Robert H.
• Format: Journal Article
• Language: English
• Published: Lawrence, KS Estuarine Research Federation 01.09.1998; Springer Nature B.V
• Subjects: Accretion; Aquatic ecosystems; Earth sciences; Earth, ocean, space; Elevation; Estuaries; Exact sciences and technology; Forced drying; Hurricanes; Hydrology; Impoundment; Levees; Marine and continental quaternary; Marshes; Minerals; Organic matter; Sedimentary soils; Sediments; Soil bulk density; Soil density; Soil formation; Soil organic matter; Surficial geology; Tides; Wildlife refuges; Louisiana; North Atlantic; Gulf of Mexico; United States; Northwest Atlantic; North American Atlantic; accretion; bulk density; Atlantic Ocean; Cs-137; vertical variations; marshes; organic materials; soils; sedimentation rates; North America
• ISSN: 0160-8347; 1559-2723; 1559-2758; 1559-2731
• DOI: 10.2307/1352840

Vertical accretion of impounded marsh and adjacent natural marsh at four sites in southwestern Louisiana was estimated in 1994 by determining the depth of a stratum containing 137 Cs deposited in 1963. With relative marsh elevation, soil bulk density, organic matter content, and organic and mineral matter accumulation rates were used to describe soil formation. Three sites were impounded in 1956 and one site in 1951. Impounded marshes had lower marsh surface elevation than natural marshes because of hydrologic isolation from tidal sediment subsidies and substrate oxidation during forced drying. The elevation of natural marshes ranged from 12 cm to 42 cm higher than the elevation of the impounded marshes in 1963 and from 20 cm to 32 cm higher in 1994. Vertical accretion between 1963 and 1994 ranged from 9 cm to 28 cm in impounded marsh and from 15 cm to 21.5 cm in natural marsh. Only in impounded marsh that remained permanently flooded was accretion greater than in natural marsh.