Relative sea level rise and Venice lagoon wetlands |
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Authors: | J W Day A Rismondo F Scarton D Are G Cecconi |
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Institution: | (1) Department of Oceanography and Coastal Sciences, Louisiana State University, 70803 Baton Rouge, LA, USA;(2) SELC srl, Viale Garibaldi 50, 30173 Mestre (VE), Italy;(3) Consorzio Venezia Nuova, Venice, Italy |
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Abstract: | Over the past century, the Venice lagoon has experienced a high rate of wetland loss and a strong net export of sediments;
currently the local Authority is running several projects for beneficial use of dredging materials. From March 1993 until
March 1995 the accretionary response of wetlands in the lagoon to changing water levels was studied. Vertical accretion, short
term sedimentation and surface elevation change were measured at six sites with varying sediment availability and wave energy.
Short term sedimentation averaged 6.85 g m−2 d−1 with a minimum of 0.06 g and a maximum of 72 g during periods of high tides and storms. Over two years accretion ranged from
0.3 to 2.3 cm/yr and surface elevation change ranged from+0.7 to −3.7 cm/yr. The sites with highest accretion were near a
river mouth and a site with strong wave energy and rapid erosion of the marsh edge with a high resuspended sediment availability.
The rate of accretion at three sites was clearly sufficient to offset relative sea level rise, but a saline site with low
sediment availability had the lowest accretion. A sediment fence significantly increased accretion at one site. The results
suggest that reduction of turbulent motion or increasing sediment availability are needed to offset wetland loss in different
areas of the lagoon. |
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Keywords: | Accretion Erosion Mediterranean Salt marsh Sedimentation |
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