Prospect Hill Hydrological Stations

• Investigators: Paul Barten, Emery Boose, Elizabeth Colburn, William Sobczak
• Contact: Emery Boose
• Start date: 2005-04-01
• End date: ongoing
• Location: Prospect Hill Tract (Harvard Forest)
• Latitude: +42.53 to +42.55
• Longitude: -72.20 to -72.17
• Elevation: 280 to 420 meters
• Taxa:
• Keywords: ground water, hydrology, stream discharge, water budget, water temperature, wetland
• Release date: 2007
• EML version: knb-lter-hfr.70.2
• Revisions: data updated every 1-2 weeks
• Abstract:

  To better understand the critical role of headwater streams and wetlands in our forest ecosystem, long-term measurements were initiated in 2005 on two small watersheds in the Prospect Hill Tract of the Harvard Forest. On Nelson Brook, weirs were installed on outlet streams of an 11-ha spruce-hemlock wetland (watershed area = 44 ha). On Bigelow Brook, pipes were installed to measure flow above (watershed = 24 ha) and below (watershed = 65 ha) a 3-ha shrub-dominated beaver swamp. Manual measurements of stream discharge, water temperature, and wetland and ground water levels were initiated in April 2005. Automated measurements were initiated in December 2007. The gauged watersheds, though adjacent and comparable in size, differ significantly in topography, soils, wetlands, stream chemistry, stream biota, land-use history, and forest vegetation, and provide an extraordinary opportunity to study the impacts of these factors on small watershed hydrology and ecology. Future plans include development of a wireless network and cyberinfrastructure tools to integrate these data with ET (evapotranspiration) data from the eddy flux towers and meteorological data from the met station to provide near-real-time estimates of water budgets for these watersheds.

• Methods:

  Experimental Design

  See online map for locations of gages and watershed boundaries. Note that the two Nelson gages measure discharge from the same watershed (parallel outlets), while the Bigelow gages measure discharge from nested watersheds.

  Nelson Brook Big Weir (NB). 120-degree V-notch weir with rectangular spillway. V-notch height = 10 in (25.4 cm). Spillway width = 13 ft (3.96 m). Watershed area = 44 ha.

  Nelson Brook Little Weir (NL). 120-degree V-notch weir with rectangular spillway. V-notch height = 4 in (10.2 cm). Spillway width = 5 ft (1.52 m). Watershed area = 44 ha.

  Bigelow Brook Lower Pipe (BL). Corrugated polyethylene pipe with smooth interior. Diameter = 30 in (76.2 cm). Length = 16 ft (4.88 m). Slope = 0.01087. Manning coefficient = 0.012. Watershed area = 65 ha.

  Bigelow Brook Upper Pipe (BU). Corrugated polyethylene pipe with smooth interior. Diameter = 24 in (61.0 cm). Length = 10 ft (3.05 m). Slope = 0.01969. Manning coefficient = 0.012. Watershed area = 24 ha.

  Measurements

  Water level: Druck 1830 2.5 psig pressure transducers. Water temperature: Campbell 107 temperature probes. At weir sites, instruments are mounted on steel brackets attached to the weirs. At pipe sites, instruments are mounted in wells 30cm below the bottom of the stream channel and 1 m upstream from the pipe intake. At each site a permanent manual gage may be used to check instrument readings. Instruments are scanned every 10 seconds and 15-minute average values are retained. Date/Time values indicate the end of the observation period. All times are Eastern Standard Time.

  Data analysis

  Stream discharge is calculated from water level (stage) using standard flow equations. At pipe sites, water depth in the pipe is estimated from measured stage using empirical rating curves. Data are checked and posted with missing, questionable, or estimated values flagged, following methods of the LTER ClimDB project. A log of events affecting station measurements is also posted.

  Operational notes

  Gages are not heated. Ice is removed regularly in winter to ensure proper flow through the gages. At Nelson Little Weir, instruments may be removed in mid-winter to prevent ice damage, in which case discharge is estimated from measured flow at Nelson Big Weir.

• Use:

  This dataset is released to the public and may be freely downloaded. Please keep the designated Contact person informed of any plans to use the dataset. Consultation or collaboration with the original investigators is strongly encouraged. Publications and data products that make use of the dataset must include proper acknowledgement. For more information on LTER Network data access and use policies, please see: http://www.lternet.edu/data/netpolicy.html.

• Related datasets: HF001