Reports
Land subsidence monitoring to assess potential effects Of groundwater withdrawals from coastal plain aquifers In Maryland: Fall, 2022 Survey
2023, Ulizio, T.P.
Administrative Report 23-02-01
Key Results
A GPS campaign was conducted October 17-24, 2022 to determine heights of nine 3d marks to assess the potential effect of groundwater withdrawals from aquifers in the Coastal Plain of Maryland. Three marks are located at major well fields in Anne Arundel County, Maryland, at the Arnold Water Treatment Plant (ARNO), the Broad Creek Water Treatment Plant (BROA), and the Crofton Meadows Water Treatment Plant (CROF). Three marks are located at or near major well fields in southern Maryland, at Cove Point State Park (COV1), Lexington Park (LEX1), and Waldorf (WAL1). An additional southern Maryland mark is located at Rosaryville State Park (ROS1), where groundwater use is relatively low. Two marks are located on the Eastern Shore of Maryland in the Blackwater National Wildlife Refuge in Dorchester County, at Money Stump (MSTP) and Peter’s Neck (PTNK). The marks at the Blackwater National Wildlife Refuge are located in low-lying areas near the shoreline of the Chesapeake Bay where inundation, caused by relative sea-level rise, makes assessing the role of land subsidence all the more critical. The GPS data were processed using the National Geodetic Survey’s Online Positioning User Service (OPUS) Projects tool utility in the International Terrestrial Reference System of 2014. The 2022 ellipsoid heights determined through OPUS Projects processing of GPS data were 3.608 meters at ARNO, -6.225 meters at BROA, 7.052 meters at CROF, -1.537 meters at COV1, -2.098 meters at LEX1, 33.822 meters at ROS1, 28.738 meters at WAL1, -35.665 meters at MSTP, and -36.056 meters at PTNK. Computed height uncertainties for all marks is +/- 0.1 cm. Uncertainty computed in the latitudinal and longitudinal positions of MGS marks is smaller than could be detected by OPUS Projects. Including these ellipsoid height data from 2022, vertical velocities have been updated for the nine 3d marks. In Anne Arundel County, ARNO is subsiding at 3.0 mm/yr., BROA is subsiding at 2.4 mm/yr., and CROF is subsiding at 2.5 mm/yr. In Southern Maryland, COV1 is subsiding at 2.7 mm/yr., LEX1 is subsiding at 1.8 mm/yr., and WAL1 is subsiding at 7.1 mm/yr. Data from ROS1, where groundwater use is relatively low, indicate an increase in ellipsoid height through time of 0.1 mm/yr. In the Blackwater National Wildlife Refuge, MSTP is subsiding at 12.5 mm/yr. and PTNK is subsiding at 6.5 mm/yr.
