Bathymetry and sediment accumulation of Triadelphia and Rocky Gorge Reservoirs
2007, Ortt, R.A., Jr., Van Ryswick, S., and Wells, D.V.
File Reports, Coastal and Estuarine Geology, File Report 2007-03
In response to a request by the Watershed Services division of the Department of Natural Resources, State of Maryland, Maryland Geological Survey (MGS) was contracted to study the bathymetry and sedimentation of Triadelphia and Rocky Gorge Reservoirs located in Howard, Montgomery and Prince George’s counties in the State of Maryland. Bathymetric data were collected for the reservoirs, current storage capacities and drawdown curves were determined, and volumes of sediment accumulation for the reservoirs were calculated. The collection, analysis, and presentation of this report were made to be consistent with the most recent bathymetric and sedimentation reports from Loch Raven and Prettyboy Reservoirs (Ortt et. al, 2000) and Liberty Reservoirs (Ortt et al, 2004) located within the State of Maryland.
Bathymetric data for the reservoirs was collected in May and June of 2004 for Triadelphia and in April and August of 2005 for Rocky Gorge. This data was collected using differential global positioning service (DGPS) techniques and digital echosounding equipment. Over four hundred thousand discrete soundings were collected and used to generate a current bathymetric model of Triadelphia and Rocky Gorge Reservoirs. Several methods of analysis were used to generate the models. The bathymetric models indicate a current storage capacity of 6.66 billion gallons [25.2 million cubic meters] for Triadelphia reservoir with a surface area of 824 acres [3.33 million square meters] and 5.54 billion gallons [21.0 million cubic meters] for Rocky Gorge reservoir with a surface area of 618 acres [2.50 million square meters].