April 8, 2013
Water flow is measured to look at seasonal changes in flow patterns and short-term changes due to rain and snow. Typically, water flow is measured on a small stream where a monitoring station called a weir can be installed to measure flow.
Alberta Geological Survey installed a water level and water-outflow monitoring system near the Frank mine entrance at the base of Turtle Mountain. We chose this location to look at the relation between precipitation on top of the mountain and the amount and rate of water coming out of the base of the mountain. In theory, this system should give a relative indication of the time it takes water to pass through the mountain after it rains or snows.
The outflow monitoring station has a V-notch weir and a pressure transducer. The weir was wedged into a thin, 20cm deep trench, with the V-notch placed approximately 10cm above the upstream channel bottom. We used the material from the upstream channel and surrounding banks to seal the sides of the weir, ensuring that water did not flow around the side or bottom of the weir. The sensor readings are recorded in millivolts (mV) and then converted by the datalogger to millimetres of water above the transducer.
Water flow has been measured near the old Frank mine entrance since 2004. Typical results show that the rate of water flowing out of the base of the mountain will increase within two to three days following a large precipitation event, indicating there is a small delay in the water filtering through the cracks in the mountain.