La Tour du Valat

Institut de recherche pour la conservation des zones humides méditerranéennes

Titre :	Effects of impoundment on vertical accretion of coastal marsh
Auteurs :	J. C. Bryant, Auteur ; R. H. Chabreck, Auteur
Type de document :	Article
Dans :	Estuaries (21(3) SEP 1998)
Article en page(s) :	416-422
Résumé :	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.

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