Watersheds

There are nine gaged watersheds at the Hubbard Brook Experimental Forest, four of which have been treated experimentally. A tenth ungaged watershed was also treated. All are shown in the map below.

The table of Hubbard Brook Watersheds provides summary data. Detailed information on each watershed can be found below the table.

sites WS 101 WS9 WS7 WS6 WS5 WS4 WS1 WS2 W3








In the map at left, click on a numbered watershed for an enlarged view.


 Hubbard Brook Watersheds
WS Area Slope* Aspect Elevation Gage type Initial Yr.

1 11.8 18.6 S22°E 488-747 90° V-notch weir 1956

2 15.6 18.5 S31°E 503-716 120° V-notch weir 1957

3 42.4 12.1 S23°W 527-732 120° V-notch weir 1957

4 36.1 15.6 S40°E 442-747 120° V-notch weir 1960

5 21.9 15.4 S24°E 488-762 90° V-notch weir,
3' wide San Dimas flume
1962

6 13.2 15.8 S32°E 549-792 90° V-notch weir,
2' wide San Dimas flume
1963

7 77.4 12.4 N16°W 619-899 120° V-notch weir,
4' wide San Dimas flume
1965

8 59.4 14.0 N12°W 610-905 120° V-notch weir,
4' wide San Dimas flume
1968

9 68.4   NE 685-910 120° V-notch weir 1995

101 12.1   SE 470-595 None 1970

  *Slope Measurements are the slope of a plane fitted to the circumference.

Watershed 1

  Related Links
Calcium addition summary
Calcium addition video
Treatment description
Biomass calculator
Phytosociology calculator
W1 grid map
W1 grid corner elevations
Selected Datasets
Daily streamflow
Streamwater chemistry
Sediment yield in weir basin
Phenology measurements
Canopy leaf chemistry
Microbial biomass and activity
Total soil respiration

Area: 11.8 ha
Slope: 18.6°
Aspect: S22°E
Elevation: 488-747 m
Gage type: V-notch weir
Initial year: 1956

Treatment: In October 1999 the Ca content of soil was increased through the application of wollastonite (CaSiO3).

Objective: To evaluate the role of Ca supply in regulating the structure and function of base-poor forest and aquatic ecosystems.

Watershed 2

  Related Links
  Treatment description
  Selected Datasets
  Daily streamflow
  Streamwater chemistry
  Sediment yield in weir basin
  Vegetation recovery on W2

Area:  15.6 ha
Slope:   18.5°
Aspect:   S31°E
Elevation:   503-716 m
Gage type:   V-notch weir
Initial year:   1957

    Treatment:
  • Devegetated for three years, 1965-1967.
  • In December 1965, all the trees and shrubs on Watershed 2 were felled and left in place.
  • During the growing seasons of 1966, 1967 and 1968 the watershed herbicides were applied to prevent vegetation regrowth.

Objective: To assess the ecosystem response to deforestation.

    Resulting Observations:
  • Discharge of snowmelt was advanced by several days.
  • Annual streamflow increased by 40, 28 and 26 percent during the 3 years of devegetation.
  • Annual average weighted value of nitrate in streamwater increased from <1 mg/L in 1965-1966 to >50 mg/L two years later.

Continued research/treatment: Monitor changes in water yield and stream chemistry.

Watershed 3

  Related Links
  Selected Datasets
  Daily streamflow
  Streamwater chemistry
  Sediment yield in weir basin

Area: 42.4 ha
Slope: 12.1°
Aspect: S23°W
Elevation: 527-732 m
Gage type: V-notch weir
Initial year: 1957

Treatment: None
Comments: Watershed 3 is used as a hydrologic reference watershed.

Watershed 4

  Related Links
  Treatment description
  Selected Datasets
  Daily streamflow
  Streamwater chemistry
  Sediment yield in weir basin
  Phenology measurements

Area: 36.1 ha
Slope: 15.6°
Aspect: S40°E
Elevation: 442-747 m
Gage type: V-notch weir
Initial year: 1960

    Treatment:
  • Strip cut in three phases during the autumns of 1970, 1972 and 1974.
  • Strips were roughly parallel to watershed contours and were progressive 25 meter wide swaths.
  • All merchantable materials were removed.

Objective: To determine how progressive strip cutting affects nutrient and hydrological cycling and stand regeneration relative to clearcutting.

    Resulting Observations:
  • Streamwater nutrient concentrations and water yield increased during and immediately after strip cutting, but not as much as following clearcutting of Watersheds 2 and 5.
  • At year 10, the strip cut had a more desirable mix of commercial species than the block cut on Watershed 101, with higher densities of yellow birch and sugar maple and lower densities of pin cherry.
  • In 1992, the vegetation on all strips was inventoried resulting in average biomass of 88 t/ha.

Continued research/treatment: Monitor changes in water yield, stream chemistry and vegetation.

Watershed 5

  Related Links
  Whole-tree harvest summary
  Treatment description
  Biomass calculator (pre-cut)
  Phytosociology calculator (pre-cut)
  Phytosociology calculator (post-cut)
  W5 vegetation map
  W5 grid corner elevations
  Selected Datasets
  Daily streamflow
  Streamwater chemistry
  Sediment yield in weir basin
  Phenology measurements
  W5 continuous revegetation survey
  Fine litterfall
  Coarse litterfall
  Throughfall
  W5 quantitative pit soil C and N

Area: 21.9 ha
Slope: 15.4°
Aspect: S24°E
Elevation: 488-762 m
Gage type: V-notch weir, San Dimas flume
Initial year: 1962

    Treatment:
  • A whole-tree harvest was conducted during the dormant season of 1983-1984 resulting in the removal of 180 t/ha of biomass.
  • Prior to treatment, the watershed was surveyed into 360 25 x 25 meter plots to be used for research.

Objective: To assess the ecosystem response to whole-tree harvest.

    Resulting Observations:
  • An increase in temperature (as much as 6°C) at the soil surface and in streams, unless streamside buffers of trees are left.
  • An increase in moisture content of the soil.
  • A maximum increase in streamflow of approximately 40 percent, and an increase in summer peak flows averaging 20 percent.
  • An increase in nitrification.
  • An increase of nutrients, especially nitrate, in soil solution subject to leaching loss or uptake by plants and microorganisms.
  • No appreciable increase in erosion and sedimentation.
  • Rapid decomposition and fragmentation of slash (75 to 80 percent breakdown in the first 14 years).
  • Rapid growth of pin cherry and raspberry from seed which had remained viable in the soil for decades; these pioneer plants conserve nutrients that otherwise might be leached from the site.

Continued research/treatment: Monitor changes in water yield and stream chemistry.

Watershed 6

  Related Links
  W6 virtual walking tour
  Biomass calculator
  Phytosociology calculator
  W6 grid map
  W6 zonation maps
  W6 grid corner elevations
  Selected Datasets
  Daily streamflow
  Streamwater chemistry
  Sediment yield in weir basin
  Phenology measurements
  Canopy leaf chemistry

Area: 13.2 ha
Slope: 15.8°
Aspect: S32°E
Elevation: 549-792 m
Gage type: V-notch weir, San Dimas flume
Initial year: 1963

Treatment: None
Comments: Watershed 6 is used as a biogeochemical reference watershed.

Watershed 7

  Related Links
  Selected Datasets
  Daily streamflow
  Streamwater chemistry
  Sediment yield in weir basin
  Phenology measurements

Area: 77.38 ha
Slope: 12.4°
Aspect: N16°W
Elevation: 619-899 m
Gage type: V-notch weir, San Dimas flume
Initial year: 1965

Treatment: None
Comments: None

Watershed 8

  Related Links
  Selected Datasets
  Daily streamflow
  Streamwater chemistry
  Sediment yield in weir basin

Area: 59.4 ha
Slope: 14.0°
Aspect: N12°W
Elevation: 610-905 m
Gage type: V-notch weir, San Dimas flume
Initial year: 1968

Treatment: None
Comments: None

Watershed 9

  Related Links
  Selected Datasets
  Daily streamflow
  Streamwater chemistry
  Sediment yield in weir basin

Area: 68.4 ha
Slope:
Aspect: NE
Elevation: 685-910 m
Gage type: V-notch weir
Initial year: 1995

Treatment: None
Comments: None

Watershed 101

  Related Links
  Treatment description
  Selected Datasets
  Foliage, leaf litter, stemflow and throughfall chemistry on W101

Area: 12.1 ha
Slope:
Aspect: SE
Elevation: 470-595 m
Gage type: None
Initial year: 1970

    Treatment:
  • Commercially logged as a stem-only, block clearcut in November 1970.
  • Branches and tops were left on site.

Objective: To study the effect of block clearcutting on watershed hydrology and nutrient flux and cycling.

    Resulting Observations:
  • Simulated streamflow increased 36 percent the first year after cutting and declined steadily until it returned to precutting levels by year six.
  • Streamwater ion concentrations increased from 295 ueq/L to 593 ueq/L two years after the harvest before returning to precutting levels by year three.

Continued research/treatment: Monitor changes in water yield and stream chemistry.
Comments:
Watershed 101 has no streamgage, so streamflow was estimated using the hydrologic model Brook2.