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 035
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 Kamloops 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 035 is completed in an unmapped, unconfined sand aquifer. The ground water level in the well has ranged from a high of 0.8 metres above ground level in March of 1972 to a low of 4.2 metres in February of 1969. The hydrograph shows that ground water levels follow a somewhat regular seasonal pattern, with maximum ground water levels occurring yearly during March and April, and minimum ground water levels occurring yearly during December and January.
The CPD curve is complex, lacks obvious seasonal trends and shows significant year to year variation. Years of below average precipitation occurred between 1972 and 1973, 1978 and 1979 and during 1987. Above average precipitation was recorded during 1969, 1980, 1981 and between 1995 and 1997.
For the period beginning in 1979
through to 2000, there is a gross similarity between the hydrograph and the
CPD curve, suggesting a link between local precipitation and ground water recharge.
At the seasonal time scale, the hydrograph seems to be responding primarily
to the spring snow-melt.