Table 1. Specifications of water quality parameter sensors.
Instrument type
Sensor
Accuracy
Resolution
0.15C
0.01C
Hydrolab
Temperature
0.2 units
(H2O multiprobe)
pH
0.01 units
Specific conductance
0.0015 to 0.1 mS/cm*
0.001 mS/cm
Fresh water
0.15 to 1.0 mS/cm*
Salt water
0.01 mS/cm
0.2 ppt
0.1 ppt
Salinity
0.2 ppm
Dissolved oxygen
0.01 ppm
20 mV
Redox
1 mV
0.45 m water
Depth
0.1 m water
0.02C
0.01C
CRREL thermistor
Temperature
0.008 m water
0.001 m water
Druck (PDCR 950)
Pressure (water depth)
100 mV
OBS3
Turbidity
1 mV
5 V = 2000 FTU
0.003 m water
Seagauge Wave/Tide
Pressure (water depth)
0.0015 m water
0.02C
0.01C
(model SBE 2603)
Temperature
0.75 m water
Seacat CTD
Pressure (water depth)
0.045 m water
0.01C
0.001C
(model SBE 1903)
Temperature
0.001 S/m
0.0001 S/m
100 mV
3 mV
OBS [5V = 2000 FTU]
* Depends on which of three auto-adjusting ranges is employed.
Water quality parameters
Water quality characteristics were analyzed
during the August and September 1993 flood and
ebb cycles at two gully sites--one in a gully
draining C Pond (called Parachute gully or drain-
age) and one in a gully draining the Bread Truck
Pond area. The same measurements were made
in the Eagle River, just downstream of the Route
Bravo access road bridge (Fig. 11).
A Campbell CR10 datalogger was used to
record data from a variety of sensors. A Hydro-
lab Model H20 Multiprobe Transmitter provided
data on a suite of parameters related to WP parti-
a. Platform.
cle and sediment transport: temperature, pH, sal-
inity, dissolved oxygen, redox and water depth
(Table 1). We also used a Druck pressure trans-
ducer to measure water level variations to 8
mm, an individually calibrated thermistor to
measure temperatures to 0.02C, and a D&A
OBS3 optical backscatter sensor to measure tur-
bidity.
Data loggers and other instrumentation were
positioned on a floating platform next to gullies,
while the various sensors were mounted on
stakes set into the small plunge pools at their
heads (Fig. 12). Sensors were placed in the
plunge pools to keep them wet at all times.
Each platform was constructed of a 4- 4-ft
b. Sensor detail.
(1.2- 1.2-m) plywood deck mounted on a 2- 6-
Figure 12. Platform and instrumentation measuring
in. (5- 15-cm) frame. Large metal eyehooks were
discharge characteristics at the Bread Truck gully
screwed into the frame on each corner (Fig 12a);
location.
9
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