The Province operates a network of observation wells to provide data on ground water level fluctuations and ground water quality information on developed aquifers in British Columbia. Observation well water levels are monitored using one of four methods: 1) manually with a wetted tape, 2) continuously using Steven's chart recorders, 3) electronically with data loggers or 4) remote monitoring using cellphone technology.
Water level data from observation wells are collected on a monthly basis by field observers and forwarded to Regional Offices. Data are then checked for errors and ommissions and forwarded to the Water and Air Monitoring and Reporting Section for final checking and storage. Water level data are referenced from ground level and the month end water level reading are entered and stored in Excel to produce a month-end hydrograph. The method of measurement and accuracy of each method are given below:
|Method of measurement||Accuracy|
|Wetted Tape Method||+/- 1 mm|
|Steven's Chart Recorder||+/- 1 mm|
|Data Logger||+/- 0.1 %|
Hydrograph Analysis - Observation Well 082
The graphs above show the ground water level in the well (top), the cumulative precipitation departure or CPD (middle) and the actual monthly precipitation for the Barkerville climate station (bottom). The CPD graph is a derivative of the precipitation data. The mean monthly precipitation over the study period is determined and the cumulative departures from the mean of the actual monthly amounts are plotted. CPD graphs can be useful in establishing how the ground water level in a particular aquifer responds to precipitation.
Observation well 082 is completed in an unmapped bedrock aquifer and in an area of high elevation (approx. 1525m) with a high annual spring snowpack. The ground water level in the well has ranged from a high of 3.2m below ground level in May of 1992 to a low of 13.1m in April of 1980. The hydrograph shows that ground water levels follow a regular seasonal pattern, with maximum ground water levels occurring yearly during May and June and minimum ground water levels occurring yearly during February, March and April.
The CPD curve is complex, and lacks obvious seasonal trends. Years of below average precipitation occurred between 1977 and 1979, and 1985 and 1987. Above average precipitation was recorded during 1981, 1984, 1996, and 1999.
The relationship between
the hydrograph and the CPD curve is difficult to analyse. One complicating factor
is the high annual spring snowpack and the year to year variability in the timing
of the spring snowmelt.