QUANTIFYING DIFFERENTIAL SUBSIDENCE RATES FROM CONTINUOUS GPS IN NEW ORLEANS EAST, LOUISIANA

With wetland losses exceeding 40 km² per year (Couvillion et al., 2011), Louisiana's coastal zone faces significant hazards associated with global eustasy and local subsidence. Research has demonstrated that late 20th century subsidence is comprised of multiple overlapping mechanisms resulting in spatially and temporally heterogeneous rates of vertical change. Identifying the processes that most influence these trends is essential for mitigating the long-term challenges for sustainability. Analysis of continuous global positioning system (GPS) and water gauge measurements was conducted to infer the impact from shallow and deep subsidence occurring on two continuous GPS reference stations in eastern Orleans Parish, Louisiana. Differential vertical motion was calculated between a station attached to a concrete slab set on the Holocene surface and another station attached to a 2-kilometer deep waste well casing that penetrates the Pliocene (Dokka, 2006). A custom workflow compiled, prepared, and processed the GPS data using precise point positioning software. Measurements were compared to values compiled from nearby water gauges and geodetic monuments. Preliminary findings, techniques employed, and an assessment of the workflow effectiveness will be presented. These results are expected to demonstrate the efficacy of using geodetic techniques for monitoring and modeling vertical change in coastal Louisiana.