Geology topics

W. Panageotou

Publications and source records attributed to W. Panageotou.

3 recordsLinked to original sources

USGS2002

Managing dredged sediment placement in open-water disposal sites, Upper Chesapeake Bay

The maintenance dredging of fine-grained sediment which accumulated in shipping channels in the Upper Chesapeake was discussed. The capacity of open-water sites was maximized in an environmentally acceptable manner to provide adequate time for the development of beneficial use or confined placement sites. The additional water column turbidity generated by dragging operations and bottom sediment movement during placement raised environmental concerns which weighted against the need to maximize capacity. The inter-agency team overseeing site management provided a mechanism to implement operational changes which maximized site capacity and insured operational use through the projected life span of the site.

Conference Paper↗

USGS1991

Consolidation and erosion of deposited cohesive sediments in Northern Chesapeake Bay, USA

Deposits of dredged cohesive sediments were monitored for changes in volume, bulk characteristics, and susceptibility to resuspension and erosion at disposal sites in Chesapeake Bay. There is a 23-48% volume reduction during the first six months, with correspondingly greater changes over longer time periods. A bulk density increase from 1.15 to 1.3 g/cm3 due to dewatering and compaction accounts for the majority of the volume change. Tidal current induced resuspension is a minor process. The observed suspended sediment load can be accounted for by erosion of only a fraction of a millimeter of sediment on each tidal cycle. ?? 1991 Springer-Verlag New York Inc.

Geo-Marine Letters↗

USGS1991

Tidal resuspension of sediments in northern Chesapeake Bay

Tidal resuspension experiments were carried out on two occasions during the winter of 1988–1989 at a disposal site for hydraulically dredged sediments in northern Chesapeake Bay to determine the influence of tidal resuspension on erosion of recent deposits. The results indicate that normal tidal erosion depths were only a fraction of a millimeter per half tidal cycle and probably did not account for the majority of the apparent sediment loss. Erosion rate was found to be a linear function of the excess of estimated shear stress over a critical value, but both the constant of proportionality ( M = 0.5 mg/cm 2 /h) and the critical shear stress ( τ c = 0.16 dynes/cm 2 were much less than many previously reported results. The most likely explanation for these low values is that the thin layer of surface sediments involved in regular tidal resuspension had only a few hours at most to consolidate between resuspension events. Observed resuspended sediment concentrations (up to 35 mg/l above background levels) were much less than those reported for previous observations of tidal resuspension in the nearby channel, presumably due to greater stratification and lower tidal velocities at the disposal site. Salinity-induced stratification of the water column is estimated to have reduced shear stresses by up to 50% relative to the neutrally stratified case. Regular tidal resuspension of a thin layer of surface sediments is implicated as a potentially important aspect of the typical benthic environment of northern Chesapeake Bay, even if it is not the most important factor in massive sediment erosion and transport.

Marine Geology↗