Submarine Groundwater Discharge In the Mississippi River Delta A Missing Hydrological Flux

Alexander S. Kolker Louisiana Universities Marine Consortium, Department of Earth and Environmental Sciences, Tulane University; Alex Breaux Louisiana Universities Marine Consortium; Jaye E. Cable Department of Marine Science, University of North Carolina, Chapel Hill; Dan Coleman Department of Earth and Environmental Sciences, Tulane University; Jihyuk Kim Department of Marine Science, University of North Carolina, Chapel Hill; Karen Johannesson Department of Earth and Environmental Sciences, Tulane University; Katheryn Telfeyan Department of Earth and Environmental Sciences, Tulane University, Mead A. Allison The Water Institute of the Gulf, Department of Earth and Environmental Sciences, Tulane University 

It is well recognized that the Mississippi River (MR) is the dominant driver of hydrological processes in coastal Louisiana. For decades, researchers have examined how surface waters from the Mississippi River (MR) impact the coastal bays that comprise the Mississippi River Delta (MRD). However, other questions remain: how well do surface hydrological and geochemical fluxes in the MRD account for the total fluxes in this system? Are there more diffuse subterranean pathways by which water flows from the MR to the coastal zone? Here we show that there are subterranean pathways that direct water from MR to the MRD. This deltaic submarine groundwater discharge averages about 1,000 m³ s^-1, and can reach 5,000 m³ s^-1 at high discharge, indicating that groundwater is an important, but overlooked part of the hydrology of coastal Louisiana (Kolker et al., 2013).