Groundwater flux estimates from Quashnet River, MA using vertical temperature profilers and seepage meters (2022-2023)

This data release contains groundwater flux estimates from twelve locations in wetlands surrounding the Quashnet River in Cape Cod, located near Mashpee and Falmouth, Massachusetts. A VTP (i.e., rod with vertical temperature sensors with known spacings and depths) was also installed at a key groundwater discharge location to estimate 1D groundwater flux through time (Sohn et al., 2024). Vertical discharge flux patterns were estimated over time using the extended Kalman Filter (EKF) recursive estimation approach of McAliley et al. (2022). The EKF method was used to recursively estimate specific discharge in discrete time when temperature measurements were acquired (i.e., hourly) at each discharge location. The methodology used here has been previously tested on both synthetic and field data in McAliley et al. (2022) where EKF methods were shown to converge to step changes in synthetic discharge data on sub-daily timescales, and residuals between observed (i.e., field observations) and estimated (i.e., EKF predictions) temperatures were generally within 0.1°C, consistent with expected measurement precision. Further information on the numerical implementation, comparisons to synthetic and field observations, as well as links to open-source code can be found in McAliley et al. (2022). To complement these estimates, discrete measurements of groundwater discharge were taken using seepage meters directly coupled to the streambed interface. Vertical head gradients were also measured in some seeps and mean hydraulic conductivity values obtained from seepage meter measurements were used to produce estimates of 1D groundwater flux (m/d) from measured head differentials. This release covers data associated with the estimation of groundwater flux from these identified discharge zones using the methods above described above.