Sediment temperature data, sediment redox data, and vertical specific discharge calculations from a salt marsh along the Herring River in Wellfleet, MA, September to December 2023 and June to July 2025

Groundwater – surface water (GW-SW) exchange plays a fundamental role in the transport of energy and solutes in coastal salt marshes, which may be influenced by flow of terrestrial groundwater and tidal fluctuations. Sediment heat tracing and redox tracking experiments were conducted at a hillslope-adjacent fringing salt marsh on the Herring River in Wellfleet, MA to test new monitoring methods for characterizing GW-SW exchange at coastal interfaces. In addition to measured sediment temperature time series from saturated peat sediments, this data release contains vertical pore water flux estimates from six locations across a small salt marsh that borders a tidal channel, adjacent to sandy upland terrain. Vertical temperature profilers (i.e., 'VTPs', a rod with vertical temperature sensors with known spacings and depths) were installed at varied spatial positions relative to the tidal channel to estimate 1D GW-SW exchange flux through time using the extended Kalman Filter (EKF) recursive estimation approach as detailed in the metadata. The EKF method was used to recursively estimate vertical pore water flux in discrete time when temperature measurements were acquired (i.e., 10-min) at each location.