Estimation of Groundwater Discharge Variability to the Gulf of Mexico Using Remote Sensing and Field Observations

Abstract:

Submarine Groundwater discharge (SGD) is an important source of solutes to marine environments and can have a profound impact on the biogeochemistry of coastal and marine ecosystems. Quantification of subsurface groundwater fluxes to the ocean is difficult, likely because of the hardship in obtaining large spatial and temporal coverages of direct SGD measurements due to extensive time and costs. Most SGD estimates using a water balance approach ignore at least one of the terrestrial hydrological components, specifically, the change in groundwater storage that may lead to large uncertainties on shorter time scales of months to year. Despite the indispensable role of SGD to human welfare and aquatic ecosystems, the potential effects of climate variability on SGD is poorly understood. This study will use an improved water budget by including the change in groundwater storage (GWS) component derived from the Gravity Recovery and Climate Experiment (GRACE) and Land Surface Models to estimate SGD rates to the Gulf of Mexico along the Texas coastline. In this area, preliminary research shows that GRACE derived GWS varies significantly at monthly to yearly time scales, thus, SGD is expected to fluctuate accordingly. This study has aimed to minimize the uncertainty in SGD estimation by using the change in the GWS component. SGD measurements, over several years, using a radon mass balance will be used to constrain spatial and temporal variability of rates estimated using the GRACE-derived GWS. This study will also evaluate the potential impact of climate variability (e.g., ENSO) on SGD using different statistical tools.