Assessing Runnel Effectiveness of Runnels in New England - Time Series Surface and Groundwater Elevations

In New England, runnels have been implemented in Rhode Island and Massachusetts with the intent to restore tidal hydrology to the marsh platform, stop the expansion of shallow water pools, and create sufficient growing conditions for high marsh graminoids (e.g., Spartina patens, Distichlis spicata, and Juncus gerardii). Long-term restoration goals of these projects include enhancing salt marsh resiliency to sea level rise and preserving high marsh habitat for specialized fauna such as the saltmarsh sparrow. Monitoring efforts of previous runnel and ditch plug removal projects have generally been tailored to one or several sites and the broader applicability and success rate of the technique has not been evaluated on a regional basis (although see Sullivan et al. 2024). To evaluate the effectiveness of runneling as a restoration tool, comprehensive monitoring of hydrology, vegetation, surface elevation, and the avian community was completed for two growing season over three years at 20 restoration sites in a modified after - control – impact (ACI) experimental design. Runnels were created between 2011 – 2022 across Maine, Massachusetts, and Rhode Island, which allowed for a space for time substitution to draw conclusions of their impact in the short (The dataset contains the time series of water elevations from water level recorders (Onset Hobo Water Pressure Transducers, 10 minute intervals) installed in creeks for surface hydrology and groundwater wells for groundwater elevations. Water pressures were transformed into water elevations in Hoboware Software and atmospheric pressure was compensated with an additional pressure transducer. Water elevations were referenced to NAVD88 m vertical datum using a Real-Time Kinematic GPS (Leica GNSS14 or GNSS16). Water elevations on dates of deployment and collection were removed, so that the time series starts on 12:00 AM on the second day of deployment and ends on 11:50 PM on the day before collection. Groundwater elevations were then uniformly adjusted ('Spring Tide Adjustment') based on the difference in maximum water elevation between the groundwater well and the local creek recorder if the difference was greater than +/- 4 cm. All spring tide adjustments and other metadata (location coordinates, duration of deployment, treatment, etc.) are provided in the dataset. Time series of water elevations were used to calculate tidal datums and flooding metrics to assess runnel restoration in R. Calculated flooding metrics and tidal datums can be found in "Effectiveness of Runnels Vegetation - Hydrology - Surface Elevation - Avian Master Dataset" (doi: 10.6084/m9.figshare.29923121.v1). Questions about the dataset can be directed to Grant McKown, University of New Hampshire, at [e-mail]