This repository contains hydrologic data collected at the Hammond Hill Research Catchment. The purpose of this dataset was to understand water flowpaths through soils, and root water uptake by Eastern hemlock and American beech along a hillslope. Spatial locations of sampling are contained in the .KMZ files. Sampling was focused on several distinct research questions, and therefore utilized two sets of sampling locations (2017-2018 & 2019-2020), provided in separate KMZ files. All files present quality controlled data (periods of sensor malfunction removed). Raw sensor outputs are provided for certain measurements (e.g. precipitation, stream depth). Specific field notes for each measurement are provided where appropriate. This repository contains the following data types:

- field notes concerning instrument installation, maintenance, and sample collection
- soil texture analysis (%sand, silt, clay) and loss on ignition
- tree density survey for 2019 - 2020 investigations
- gross precipitation (15-min interval; January 2017 - present)
- gross precipitation water isotopic composition (2H, 18O) (weekly interval; January 2017 - February 2018)
- canopy throughfall water isotopic composition (2H, 18O) (weekly interval; June 2017 - November 2017)
- stream depth, discharge, and stream temperature (10-min interval; January 2017 - present)
- stream rating curve measurements (velocity, area, wetted perimeter; January 2017 - present)
- stream water isotopic composition (2H, 18O) (weekly interval; January 2017 - January 2018)
- snow water equivalent (weekly interval; January 2017 - present)
- snow water isotopic composition (2H, 18O) (weekly interval; January 2017 - January 2018)
- volumetric soil water content measured at six locations along a hillslope (weekly interval; January 2017 - December 2017)
- bulk soil water isotopic composition (2H, 18O) measured at six locations along a hillslope (weekly interval; January 2017 - December 2017)
- american beech and eastern hemlock stem water isotopic composition (2H, 18O) measured at six locations along a hillslope (August 2017, November 2017, June 2018)
- tree sapflux measurements (July, 2020)

Precipitation was measured with a tipping bucket rain gage (TR-525-S-U; precision 0.2mm; accuracy, +/- 3%) at a 15-minute time interval. Tipping bucket precipitation estimates were corroborated by weekly accumulated precipitation depths in a nearby accumulation gage. Stream depth was measured with a pressure transducer (U20-001-04) at a 10-minute time interval. Stream depth was corroborated with weekly manual stream depth measurements. Stream discharge was computed via a rating curve. Volumetric soil water content measurements were taken of the top 12 cm weekly with a probe (CS658, resolution 0.05%, accuracy 3%). Each value presented is the average of five independent measurements. Snowpack water equivalent was measured with a snow core tube. Bulk soil water samples (depth 5 -10 cm) were collected weekly. Plant stem samples were collected seasonally. All bulk soil and xylem water were extracted via cryogenic vacuum extraction for a duration of 120 minutes. Weekly samples of precipitation, streamwater, and snowpack (when present) were collected. All waters were analyzed for 2H and 18O. Soil and xylem water were analyzed on a Los Gatos Research analyzer (OA‐ICOS; IWA‐35EP, precision of 18O and 2H were 0.5 and 0.1 per mill respectively). All other water samples were analyzed on a Thermo Delta V isotope ratio mass spectrometer (precision of 0.5 and 0.24 per mill respectively).

Related Publications:
Knighton J., Coneelly, J., Walter, M. (2019). Possible Increases in Flood Frequency Due to the Loss of Eastern Hemlock in the Northeastern US: Observational Insights and Predicted Impacts. Water Resources Research. DOI: 10.1029/2018WR024395

Knighton J., Souter-Kline, V., Volkmann, T., Troch, P., Kim, M., Harman, C., Morris, C., Buchanan, B., Walter, M.T. (2019). Spatial and Topographic Variations in Ecohydrologic Separation in a Small, Temperate, Snow-Influenced Catchment. Water Resources Research. DOI:10.1029/2019WR025174

Knighton J., Kuppel, S., Smith, A., Sprenger, M., Soulsby, C., Tetzlaff, D. (2020). Using Isotopes to Incorporate Tree Water Storage and Mixing Dynamics into a Distributed Ecohydrologic Modelling Framework. Ecohydrology. DOI: 10.1002/eco.2201