The stage record for 1990 was obtained by systematic manual readings of the staff gage through the field period (n = 542). Observations were generally made on the hour, averaging 12 per day, and always in conjunction with discharge measurements. During periods of rapidly changing stage, observations were made more frequently. Recording was continued each day until after the peak stage had occurred. Details of stage measurements during 1991 and 1992 are discussed in section 3, Equipment/calibration.
The 204 discharge measurements made in the inlet stream during the three years were all done by measuring water depth and velocity at a series of verticals across the stream. The locations of these verticals were defined by tags along a polypropylene tag line, set up each year above the rated section. The principal difference between measurements over the three years was in the number of verticals used, as detailed below. The specific equipment used to measure discharge, and it's operation, are discussed in section 3. Computation of discharge is discussed further in section 6.
The spacing between verticals for all 1990 discharge measurements was 0.50 m. Depending upon the stage, this spacing resulted in as few as six verticals. This small number of measurements increased the potential error in the discharge computations. The spacing between verticals along the tag line was adjusted in 1991 to be inversely proportional to current velocity. Practically, this meant that the minimum spacing was 0.125 m or 0.25 m in the fastest current at the center of the channel. Vertical spacing was again reduced in 1992. This was done in conjunction with a new tag line, with tags 0.10 m apart over the highest velocity portion of the cross section. This reduced spacing resulted in as many as 33 verticals.
Water temperature measurements made in 1990 were primarily made approximately 175 m downstream from the gaging station site, close to camp. This downstream site was also used in 1991 and 1992 to measure water temperature, whenever conductivity measurements were made. The primary water temperature measurement site in 1991 and 1992, however, was at the gage site upstream. The gaging station site sensor was held at a fixed position in the streamwater, close to the right edge of the stream. Generally, the sensor was 5 to 10 cm above the channel bed. Water depth over the sensor varied according to stage.
The procedure for obtaining all samples taken with the DH-48 sampler involved lowering the sampler at a uniform rate to the bottom, instantly changing direction, and raising the sampler to the surface at a uniform rate, although not necessarily the same as that taken in descent. The target sample volume was 350-400 mL. Smaller samples were supplemented by integrating the vertical again; samples larger than the capacity of the tilted bottle were rejected, and the vertical was resampled.
Dip samples were obtained on a very few occasions, without the DH-48 sampler, by manually moving bottles vertically through the water column (cf. Østrem, 1975). This method was only used when either: (1) there was no perceptible sediment in suspension (e.g. extremely clear water at low discharge), or (2) to quickly sample early season pulses of high sediment concentration accompanied by significant concentrations of snow and ice, which tended to clog the sampler nozzle (resulting from slushflows in upstream tributaries). (IMAGE: slushflow deposit 1500 m upstream) Most electrical conductivity (EC) measurements were made at a main channel monitoring site approximately 175 m downstream from the gaging station site. The exceptions to this were 1991 readings through early July, which were made in the lower volume distributary, located closer to camp. Several comparisons indicated that differences between the two sites were minor, unless flow in the camp channel was greatly reduced. In two tests at such times, the EC in the camp channel was 30-35 percent greater.
EC measurements were typically made one to three times daily. Measurements were generally irregular in 1990, although emphasized morning readings; a thrice daily regime was followed in 1991; and early morning readings were made in 1992. The total number of readings for each season, 1990-92 were 45, 100, and 46.