HR: 0800h
AN: H41B-0502    [Abstracts]
TI: Medium-term sediment accumulation in the urbanized lower Hudson River estuary
AU: * Zhu, J
EM: jun.zhu@umb.edu
AF: University of Massachusetts Boston, Department of Environmental, Earth and Ocean Sciences, 100 Morrissey Blvd., Boston, MA 02125-3393, United States
AU: Wilson, B A
EM: bawilson13@gmail.com
AF: University of Massachusetts Boston, Department of Environmental, Earth and Ocean Sciences, 100 Morrissey Blvd., Boston, MA 02125-3393, United States
AU: Gontz, A M
EM: allen.gontz@umb.edu
AF: University of Massachusetts Boston, Department of Environmental, Earth and Ocean Sciences, 100 Morrissey Blvd., Boston, MA 02125-3393, United States
AU: Tian, Y Q
EM: yong.tian@umb.edu
AF: University of Massachusetts Boston, Department of Environmental, Earth and Ocean Sciences, 100 Morrissey Blvd., Boston, MA 02125-3393, United States
AU: Olsen, C R
EM: curtis.olsen@umb.edu
AF: University of Massachusetts Boston, Department of Environmental, Earth and Ocean Sciences, 100 Morrissey Blvd., Boston, MA 02125-3393, United States
AB: Estuaries are dynamic systems that naturally act as sediment traps at the land-ocean interface. Sediment accumulation in urbanized systems like the lower Hudson River estuary is also affected by human activities such as channelization, dredging, harbor construction, and ship traffic. Sediment accumulation in this urban estuary was examined using a unique research approach that links Geographic Information Systems (GIS) with radioisotopic (Cesium-137) dating over the medium-term (decadal to centennial) time scales. Raster analyses were performed to determine sediment accumulation/erosion patterns based on bathymetric data over the last 100 years. These results indicate that sediment accumulation was negligible in the natural river channel, where sediment surface is in equilibrium with its physical regime. Protected marginal areas (such as abandoned harbor slips) and previously dredged areas (such as around the southern tip of Manhattan Island and in the Bay Ridge Flat area) are currently sites of rapid sediment accumulation. Vertical profiles of Cesium-137 measured in sediment cores collected in the lower Hudson River estuary provided time-marker horizons that could be used to estimate sediment accumulation rates over a 40-year time span (1960-70 to 2007). Results from Cs-137 profiles confirmed the raster analyses and indicated that sediment accumulation rates ranged from 0 to 1 cm/yr in the natural river channel and subtidal bank areas, to as high as 15-20cm/yr in areas affected by human activities (Pier 32, Battery and Bay Ridge Flat). Overall, GIS and radioisotopic dating are complementary to each other and combined they provide a more accurate estimate for medium-term sediment accumulation in the lower Hudson River estuary.
DE: 1641 Sea level change (1222, 1225, 4556)
DE: 1824 Geomorphology: general (1625)
DE: 1862 Sediment transport (4558)
DE: 3022 Marine sediments: processes and transport
DE: 4217 Coastal processes
SC: Hydrology [H]
MN: 2007 Fall Meeting