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 282
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 Penticton Airport 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 282 is completed in an unmapped, confined, sand and gravel aquifer. The ground water level in the well ranged from a high of 2.2m below ground level in June 1997 to a low of 12.0m in November 1989. The hydrograph shows that ground water levels follow a somewhat regular, seasonal pattern, particularly from 1995 to 2000 with maximum ground water levels occurring during May and June and minimum ground water levels occurring during December and January.
The CPD curve is complex, and lacking obvious seasonal trends. Years of below average precipitation occurred during 1985, 1987, 1991 and 2000. Above average precipitation was recorded between 1981 and 1983, 1995 and 1997, and during 1990 and 1993.
There is no apparent
relationship between the magnitude of fluctuations in the CPD and hydrograph
plot suggesting that the aquifer may be recharged by other local sources (creeks).
The long-term trend observed in the hydrograph, however, corresponds with the
CPD curve and local precipitation also contributes significantly to ground water