Watershed Research Infrastructure and Data
Research in Handcart Gulch was initiated by the donation of four mineral exploration
boreholes to the U.S. Geological Survey in 2003. Subsequent funding from the
U.S. Geological Survey Mineral Resources and Mendenhall Post-Doctoral Research
Programs has allowed research and monitoring to continue (Caine and others, 2006; Kahn and others, 2008; and Verplanck and others, 2008 Chapters I and J). Watershed infrastructure and instrumentation includes:
- Four-wheel drive accessible roads from the east or west, largely maintained by the U.S. Forest Service.
- Four deep, fully cored, logged, screened, and pumping tested boreholes (total depths = 610, 479, 1067, and 533 meters).
- Nine shallow, fully logged, screened, and pumping tested boreholes along the trunk stream (total depths = 3, 4, 7, 8, 9, 31, 41, 46, and 53 meters). Four of these are bedrock wells paired with surficial deposit wells including one screened in the rock glacier.
- Drill core logging includes quantitative mineralogy and elemental chemistry.
- Geophysical depth logs include caliper, acoustic and optical televiewer imagery, heat-pulse flow metering in static and stressed conditions, fracture orientation and intensity, temperature, fluid conductivity, magnetic suscepatability, and natural gamma.
- Intermitent water levels and temperature from 2003 to 2006 and continuous data from dedicated pressure transducers and thermisters from 2007 to the present.
- Single well hydraulic tests in each well with estimates of hydraulic conductivity and storativity.
- A dedicated stilling well stream gage with pressure transducer and thermister data. Time series data from water year 2004 and 2008 to the present.
- A one-time tracer dilution study of the stream from its inception at the toe of the rock glacier 2.1 km down stream. Total discharge, inflow discharge and chemistry were determined.
- Yearly geochemical sampling for elemental chemistry and tritium / helium age and recharge temperature determinations of surface and ground waters.
- Meteorological station installed in 2008 at ~3,505 meters (11,500 feet) for continuous reading of surface air temperature, ground temperature and soil moisture at ~0.5 meters depth, rain and snow, wind speed and duration, and incoming solar insolation. These data will be used to estimate potential evapotranspiration.
Figure 8: Assorted well and other data from Webster Pass and Handcart Gulch. [Click on image for large version.]
Figure 9: An example of composite geophysical and lithological logs from Handcart
Gulch wells. Optical televiewer image (OBI) shows surface deposits/bedrock
interface and sinusoidal traces of open fractures in WP4 (all other logs from
shallow HCBW1 next to the trunk stream). Fracture orientations derived from
the acoustic televiewer image (ABI) plotted on an equal area projection are
consistent with outcrop and regional fracture orientations. Heat-pulse flow
meter (HPFM data shown as FLOW) indicates flow direction and magnitude in the
well and does not correlate with fracture orientation or fracture intensity.
Inflow does correlate with temperature and conductivity. Lithology and hydrothermal
alteration log data are also shown for HCBW1 shallow bedrock well (red layered
material is ferricrete, green diagonal pattern is amphibolite; P = propylitic
alteration and A = quartz-sericite-pyrite or argillic alteration). See Caine and others (2006) for details. gpm, gallons per minute; µS/cm, microsiemens
per centimeter; frac/ft, fractures per foot; deg C, degrees Celsius; m, meter. [Click
on image for large version.]
Figure 10: Acoustic televiewer logging in WP2. The sinusoidal lines on the computer screen are fractures intersecting the cylindrical borehole walls. [Click on image for large version.]
Figure 11: Hydraulic test in artesian well HCBW2. [Click on image for large version.]
Figure 12: Tracer dilution study results showing examples of discharge (cubic feet per second), pH, apparent tritium / helium water age for springs, surfical and bedrock wells, and dissolved constituent load data for aluminum (Al), sulfate (SO4), zinc (Zn) and copper (Cu) as a function of downstream distance along the trunk stream in Handcart Gulch. Constituent concentrations for springs (inflows) and bedrock wells (BW) are also shown. [Click on image for large version.]
Figure 13: Handcart trunk stream gage in naturally incised flume in hard ferricrete. [Click on image for large version.]
Figure 14: (a) Box plot of monthly stream discharge (Q) averaged from daily data. Each box shows Q for the 75th percentile (top line), median (black square), mean (intermediate line), and 25th percentile (bottom line). Whiskers show the 10th and 90th percentiles, top and bottom respectively. (b) Mean monthly Q from (a) plotted with mean monthly stream water temperatures, and surface air temperatures collected at the Jackwhacker Gulch SNOTEL site. Kahn and others, 2008. [Click on image for large version.]
Figure 15: Flow chart illustrating the simulated water budget form the watershed scale groundwater flow model (Kahn and others, 2008). [Click on image for large version.]
Figure 16: Handcart meteorological station at tree line on rock glacier at 3,505 meters (11,500 feet). [Click on image for large version.]