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 217
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 Grand Forks 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 217 is completed in a shallow unconfined sand and gravel aquifer. The ground water level in the well ranged from a high of 1.8m below ground level in July 1997 to a low of 3.6m in January 1988. The hydrograph shows that ground water levels follow a regular, seasonal pattern, with maximum ground water levels generally occurring during June and July 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 between 1985 and 1989 and during 1994 and 1998. Above average precipitation was recorded between 1980 and 1983 and 1996 to 1998.
water levels in the shallow unconfined sand and gravel aquifer generally fluctuate
directly with river stage (Kettle river) and the regular seasonal pattern observed
in the ground water level hydrograph appears absent in the CPD curve.