would not be recommended due to calcite precipitation on the tarp and detention of
flow that could cause shifts in certain geochemical parameters.
3.4.3 Stream Discharge
Discharge of the cave stream is measured using a 90
V-notch weir and a pressure
transducer to measure the hydraulic head behind the weir (Fig. 8). The V-notch weir
was constructed in 2009 and was retrofitted using concrete in 2011 to prevent
leakage. Transducer measurements are recorded every 10 min to calculate discharge. In 2012, the transducers were replaced with transducer and barometric
loggers from the same manufacturer as other equipment in the cave to allow for
use of one data shuttle and software package for all instrumentation in the cave. The
benefits of using instrumentation and software from one manufacturer are discussed
in more detail below.
3.4.4 Stream Chemistry
A multiparameter sonde was installed in the stream from 2010 to 2011. Similar to
the dripwater sites, it was difficult to maintain and calibrate the sensors and, as a
result, the sonde was replaced in 2011 with an SCT logger.
3.4.5 Cave Atmosphere
Cave air temperature is monitored at each dripwater site using a temperature sensor
connected to a data logger. The barometric logger installed near the stream weir
also measures cave air pressure.
3.5 Instrumentation Maintenance
An important consideration of cave monitoring projects is maintenance of equipment and instrumentation. Maintenance is conducted on a monthly or bimonthly
basis in conjunction with data download from logging sensors. As instruments can
fail, and transportation to the site and within the cave takes time and effort, it is
useful to have at least one extra of commonly used equipment (i.e., rain gauge, data
logger, SCT logger) readily accessible. Tools, instrument manuals, and replacement batteries are essential to bring for each monitoring event, to allow for routine
maintenance and troubleshooting in the cave.
3.5.1 Sensor and Instrument Maintenance
As discussed above, maintenance of sensors in the multiparameter sonde became
challenging due to requirements of frequent calibration and fouling. The change to
220
M.E. Schreiber et al.
flow that could cause shifts in certain geochemical parameters.
3.4.3 Stream Discharge
Discharge of the cave stream is measured using a 90
V-notch weir and a pressure
transducer to measure the hydraulic head behind the weir (Fig. 8). The V-notch weir
was constructed in 2009 and was retrofitted using concrete in 2011 to prevent
leakage. Transducer measurements are recorded every 10 min to calculate discharge. In 2012, the transducers were replaced with transducer and barometric
loggers from the same manufacturer as other equipment in the cave to allow for
use of one data shuttle and software package for all instrumentation in the cave. The
benefits of using instrumentation and software from one manufacturer are discussed
in more detail below.
3.4.4 Stream Chemistry
A multiparameter sonde was installed in the stream from 2010 to 2011. Similar to
the dripwater sites, it was difficult to maintain and calibrate the sensors and, as a
result, the sonde was replaced in 2011 with an SCT logger.
3.4.5 Cave Atmosphere
Cave air temperature is monitored at each dripwater site using a temperature sensor
connected to a data logger. The barometric logger installed near the stream weir
also measures cave air pressure.
3.5 Instrumentation Maintenance
An important consideration of cave monitoring projects is maintenance of equipment and instrumentation. Maintenance is conducted on a monthly or bimonthly
basis in conjunction with data download from logging sensors. As instruments can
fail, and transportation to the site and within the cave takes time and effort, it is
useful to have at least one extra of commonly used equipment (i.e., rain gauge, data
logger, SCT logger) readily accessible. Tools, instrument manuals, and replacement batteries are essential to bring for each monitoring event, to allow for routine
maintenance and troubleshooting in the cave.
3.5.1 Sensor and Instrument Maintenance
As discussed above, maintenance of sensors in the multiparameter sonde became
challenging due to requirements of frequent calibration and fouling. The change to
220
M.E. Schreiber et al.