DECADAL SEDIMENT ACCUMULATION IN THE LOWER HUDSON RIVER ESTUARY - A COMBINED GEOCHEMICAL AND GEOSPATIAL APPROACH

Estuaries are dynamic non-steady-state systems that occur at the land-ocean interface, and are affected by a growing human population and associated urbanization. Estuaries also serve as traps for sediment and particle-associated contaminants, nutrients, and organic carbon, and thus, they are important sites for contamination monitoring and control. In this study, a combined geochemical and geospatial research approach was applied to examine sediment accumulation in the lower Hudson River estuary (spanning from the George Washington Bridge to the Narrows Bridge) over a decadal time-scale in association with urbanization of New York City and New York/New Jersey Harbor development. The geochemical research approach used Cesium-137 (¹³⁷Cs) sediment profiles to estimate average sediment accumulation rates over the past 50 years. The geospatial research approach used geographic information system (GIS) to quantify sediment accumulation rates by running raster analyses on historical navigational charts from 1930 to 2001. Our results show that there was a large degree of spatial and temporal heterogeneity in sediment accumulation/erosion within the lower Hudson River estuary. Anthropogenic impacts (such as channel-dredging and spoil-dumping) caused sediment accumulation to occur at extremely high rates (> 20cm/yr) on the eastern bank of the Hudson River near George Washington Bridge, and caused sediment erosion to occur in the main river channel. Future work includes conducting more detailed geochemical surveys and obtaining more updated navigational charts for geospatial analyses.