Hydrological Field Measurement Protocols for CPCRW at the Bonanza Creek LTER

Stream stage is recorded at the C2, C3, C4, CJ, PJ, and PC gauging stations Campbell Scientific CR10X/21X data loggers and a Microswitch 5-psi pressure transducer. Five consecutive measurements are averaged every hour and recorded. Parshall flumes are used at the C2, C3, and C4 to obtain continuous discharge data. Discharge measurements are made using USGS standards at different stage levels to confirm the discharge data obtained from the data logger. Pressure transducers and data loggers are installed immediately following melt from the flumes. At the CJ, PJ, and PC gauging stations, discharge measurements are made at various stages to produce rating curves from which continuous discharge measurements are calculated. Point stream flow measurements are conducted from the initiation of snowmelt until late September when freeze-up occurs.

Snow measurements are conducted including snow depth, snow water equivalent, and snow ablation. Snow water equivalent measurements are made using an Adirondack snow sampler. At each site, 10 snow water equivalent and 50 snow depths measurements are averaged following the combination technique of Rovansek et al (1993). A Wyoming snow gauge and snow pillow are also maintained. Monthly snow surveys are conducted at the Wyoming snow gauge, the snow pillow, and near the C2 sub-watershed. Extensive snow surveys of CPCRW are conducted in mid-March, followed by periodic measurements through the completion of snowmelt.

Soil moisture content is measured at 5 locations in CPCRW. At each site, Campbell Scientific CS615 soil moisture probes were installed horizontally into small pits and connected to a Campbell Scientific CR10(X) data logger that record on hourly intervals. The data obtained from the CS615 probes are used to calculate the dielectric constant of the soil. The Topp (1980) equation for mineral soils and Stein and Kane (1982) equation for organic soils are then applied to obtain the soil moisture content. Installation of additional soil moisture probes will include thermistors adjacent to the soil moisture probes. An in-situ calibration technique described by Weitz et al (1997) will be used calibrate the soil moisture probes in both the organic and mineral soils.

Four complete meteorological stations, located in the C4 valley bottom, near Caribou-Peak, near the confluence of Caribou and Poker Creeks, and along Caribou Creek, record hourly wind speed, wind direction, air temperature, relative humidity, precipitation, ground temperature and various radiation terms. Air temperature and precipitation are also recorded on Helmer’s Ridge and along Caribou Trail at elevations 1600 ft and 2100 ft. Hourly evaporation is recorded using a standard evaporation pan near the confluence of Caribou and Poker Creeks.

References:

Rovansek, R.J. Kane, D.L., Hinzman, L.D., 1993. Improving Estimates of Snowpack Water Equivalent using Double Sampling. Eastern Snow Conference. Quebec Canada. pp157-163.

Stein, J., and Kane, D.L., 1983. Monitoring the Unfrozen Water Content of Soil and Snow Using Time Domain Reflectometry. Water Resources Research, Vol. 19, No. 6. pp 573-1584.

Topp, G.C., Davis, J.L., and Annan, A.P., 1980. Electromagnetic Determination of Soil Water Content: Measurements in Coaxial Transmission Lines. Water Resources Research, Vol. 16. No. 3. pp 574-582.

Weitz, A.M., Grauel, W.T., Veldkamp, E., 1997. Calibration of Time Domain Reflectometry Technique Using Undisturbed Soil Samples From Humid Tropical Soils of Volcanic Origin. Water Resources Research, Vol. 33, No. 6. pp 1241-1249.