Final snow survey

Final snow survey of the season today shows continuing melt through March. The snow melts twice as fast in the larch stand compared to the mature cedar stand due to the lack of shading and higher net radiation under the deciduous canopy without leaves.

Snow survey summary, snow water equivalent
Larch: 35 cm (down from 51 cm to 35 cm over 16 days = 1.0 cm/day)
Mature cedar: 28 cm (down from 36 cm to 28 cm over 16 days = 0.5 cm/day)

A discharge measurement was also taken under rainy and very cold conditions to confirm the stage-rating curve after the winter and before the main snowmelt season.

Stage = 57.25 cm, Q = 3.14 m3/s

Log jam removal

Today's main task was to remove the log jam below the gauging station, in addition to downloading the Hobo water level recorder and resetting it under the water by the staff gauge. This was cold work in a stream swollen with snowmelt water. After removing the log jam, the water level immediately dropped by about 55 mm at the gauging station, confirming a backwater effect which had been influencing stage measurement.

March snow survey

Snow survey results showed that the snow water equivalent (SWE) was less than in February, with about 51 cm SWE in the larch stand and about 35 cm SWE in the cedar stand (see photo above).

The snowmelt season has already begun with two runoff events early March, and the winter season also shows several significant runoff events during January and February (see hydrograph below).

The photo above shows a small log jam below the gauging station that was likely having an impact on the gauged water level and the stage-rating curve. The log jam was removed two days later on March 8th, when water levels immediately dropped by about 55 mm at the gauging station.

February snow survey

Perfect mid-winter conditions today for our February snow survey. Recent fresh snow accumulation made for pleasant snow conditions, and calm and sunny weather to enjoy snow survey with several members new to the activity.

Snow water equivalent summary
Larch: 55 cm
Mature cedar: 39 cm

January snow survey

Today four members joined me for their first experience of snowshoeing and snow survey. Conditions were tough with heavy wet snow falling throughout the day, after a two week period of relatively heavy snowfall. We took 20 measurements in the larch stand to give the following mean values. Compared with recent years, the snowpack is relatively large.

Snow survey (Larch stand)
Depth: 112 cm
Density: 0.275
Snow water equivalent: 30.8 cm

Autumn rains bring higher baseflows

The hydrograph above shows the typical situation in autumn season when more frequent rainfalls and decreasing evapotranspiration leads to rising levels of baseflow. The interval between the rainfall events is becoming shorter, and note how the baseflow in between events is steadily rising. The baseflow level will remain high into December, only decreasing once the temperatures drop sufficiently for precipitation to change from rainfall to snowfall.

Stage recorder battery change

Early autumn is a good season for the annual change of the batteries in the Kadec stage recorders (main river and tributary sites). Cold winter temperatures are hard on batteries, but this way we enter the winter season with fresh batteries. I also did the bi-monthly download of the Hobo stage recorder, which acts as a back-up stage recorder on the main river. Again, very close agreement between the two stage recording systems which is always very reassuring (upper hydrograph). The lower recent hydrograph data shows mainly low flow conditions from late September into October.