Synoptic soil moisture measured at plot scales across the Mid-Atlantic region

This file contains the raw synoptic soil moisture measurements reported and analyzed in Scaife et al., 2021. In this study, we synthesized measurements of soil moisture collected at the plot scale (defined as an area less than 100 m2) from across 212 sites in eight catchments over three regions of the eastern U.S. These sites included a range of land uses, landcovers, geomorphology, and soil conditions. Soil moisture was measured by several researchers over a period from 2001 to 2015 using comparable methods. The sampling strategies focused on spatial variation in soil moisture at plot and hillslope scales to capture spatial patterns within plots and along hillslopes. As a result, all sites were sampled from riparian or near stream to upland although there were variable arrangements of sampling plots within each watershed. Plots were sampled on weekly to monthly intervals depending on the site and season.

Soil moisture was measured using a standard handheld TH2O Thetaprobe ML2x (Dynamax, Inc, Houston, TX) to a 6 cm depth equal to the prong length. To insert the probe, the organic rich litter layer was removed exposing mineral soil and the probe was vertically inserted. Measurements were replicated 10 to 20 times per plot and made 24 hours or more after rainfall cessation to minimize the impacts of storms. Locations of each individual measurement within a 25 m2 plot was determined using a “random walk”. Replicating soil moisture measurements 10 to 20 times in each plot provides greater confidence in estimates of average soil moisture and helps characterize spatial heterogeneity of soil moisture at a given wetness level. Soil moisture was reported as the volumetric water content which relates the volume of water to the volume of soil with units vol/vol.

For more information, see the published manuscript: Scaife, C.I., Duncan, J.M., Lin, L., Tague, C., Band L.E. (2021). Are spatial patterns of soil moisture at plot scales generalizable across catchments, climates, and other characteristics? A synthesis of synoptic soil moisture across the Mid-Atlantic. Hydrological Processes.