Dams and Sediment in the Hudson (DaSH) - NERRS/NSC(NERRS Science Collaborative)

Dams and Sediment in the Hudson answered key questions about how dam removal will impact conditions in the estuary and offered surprising new findings about tidal marshes in the Hudson River valley. The project used a multidisciplinary approach that combined field observations with an analysis of sediment transport using a proven hydrodynamic model.

Researchers surveyed 17 representative dams in the Lower Hudson River watershed by measuring water depth and sediment thickness and collecting sediment cores. Results were extrapolated to the 1700 registered dams located on tributaries of the Lower Hudson River to estimate the total amount of sediment trapped in the watershed. These observations were complemented by an analysis of sediment discharge data from existing monitoring stations on tributaries to characterize typical sediment input to the estuary and conditions following major storm events. A numerical model of circulation and sediment transport in the estuary was used to evaluate the impact of dam removal scenarios. To understand sediment contributions to tidal wetlands along the Hudson, researchers collected transects of sediment core from 6 representative tidal wetlands and coves. Geochronological data of sediment cores combined with an analysis of historical and aerial photos was used to assess when wetlands began to form and their rates of accumulation.

Results show that dam removals would have a minimal impact on sediment supply to the estuary and tidal wetland growth. Only 10% of dams in the Lower Hudson River watershed are effective sediment traps, and the potential amount of sediment that would be released if all dams were removed represents less than 2 years average sediment input from the watershed. Tidal wetlands along the Hudson were found to be remarkably young and rapidly accumulating sediment despite the presence of dams, growing vertically at rates several times faster than sea level rise.

Hundreds of dams built on tributaries of the Hudson River estuary have outlived their usefulness. Removing these relic dams is a priority for the state of New York in order to improve aquatic habitat connectivity, restore fish spawning grounds, and reduce the risk of dam failure. For those who regulate and permit dam removal, questions about the fate of sediment trapped behind these dams and its potential impact on downstream habitat has encumbered the permitting process. To better understand how sediment released by dam removal in the lower Hudson River watershed will affect the estuary, including the potential for dam-derived sediments to help offset sea level rise in tidal wetlands, the Dams and Sediment in the Hudson project brought together a collaborative team of scientists and stakeholders to research key questions and provide practical tools to regulators and practitioners.

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David Ralston

Woods Hole Oceanographic Institution

dralston@whoi.edu

(508) 289-2587

Partners:

Consensus Building Institute

Hudson River NERR, NY

University of Massachusetts–Amherst

Woods Hole Oceanographic Institution

==About the data

In addition to the sediment data links listed in the URL section, is also:

Hudson River Estuary Model Simulations of Dam Sediment Releases

Model outputs from simulations of dam removal scenarios, generated using a hydrodynamic and sediment transport model for the Lower Hudson River. Data access: Data files are large (32 GB/file, 60 files per case) and cannot be served remotely at this time. Data are available by contacting David Ralston.

The distributor does not assume liability.

None

Cite this dataset when used as a source: NOAA retains the right to analyze, synthesize and publish summaries of the NERRS/NSC data. The NERRS/NSC retains the right to be fully credited for having collected and process the data. Following academic courtesy standards, the NERR site where the data were collected should be contacted and fully acknowledged in any subsequent publications in which any part of the data are used. The data enclosed within this package/transmission are only as accurate as the quality assurance and quality control procedures that are described in the associated metadata reporting statement allow. The user bears all responsibility for its subsequent use/misuse in any further analyses or comparisons. The Federal government does not assume liability to the Recipient or third persons, nor will the Federal government reimburse or indemnify the Recipient for its liability due to any losses resulting in any way from the use of this data. Requested citation format: NOAA National Estuarine Research Reserve System (NERRS) Science Collaborative(NSC).

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This information is detailed within the project links.

This information is detailed within the project links.