Initiating a New Baseline of Vertical Land Motions in the Chesapeake Bay

Abstract:

The Chesapeake Bay (CB) is a sea-level rise hotspot along the North American Atlantic coast, partly due to rapid land subsidence with contributions from post-glacial rebound and anthropogenic groundwater extraction (among other influences). Many previous studies have measured vertical land motions (VLM) in the area using a variety of approaches with contradicting results. This study aims to (1) collect campaign-style Global Positioning System (GPS) data annually over a five-year period to provide a new baseline of VLM for the CB area and (2) elucidate the geologic and anthropogenic VLM drivers. Here, we present methods and outcomes of the first campaign (October 2019) that collected initial epoch GPS observations. Surveyors successfully collected data from 53 geodetic benchmarks. The same antenna type (Trimble Zephyr Geodetic II) was used for 18 of the 53 stations; 22 stations used the same type of receiver (Trimble NetR9), and 46 of the 53 tripods (Seco graduated collapsable 2 m) were both calibrated and measured to the 0.0001 m. All data is being quality-checked using the open-source program Teqc. Of the 45 stations for which we have quality-checked the data, we found an average of 89.61 hours of usable data were collected per station and there was an average of 5,528 cycle slips per daily file. RINEX files will be archived for open-access at the NSF geodesy facility UNAVCO to abide by FAIR data principles. To test the robustness of our estimates of VLM, we will develop two independent velocity solutions using GAMIT-GLOBK and OPUS Projects. Implications will yield a more accurate understanding of anthropogenically-linked sea-level rise in the CB.