The Mark VI Groundwater Standpipe for Measuring Seepage through Salmon Spawning Gravel

Abstract

The groundwater standpipe is a length of pipe, pointed at one end, and has a number of perforations near the point. This is driven into the gravel, where the groundwater flows through it. The permeability of the gravel is measured by lowering the level of water inside the standpipe, one inch below the level outside, and measuring the rate of inflow. The apparent velocity through the gravel is measured in terms of the rate of dilution of a colour solution in the standpipe. A colour is introduced, and its rate of dilution determined from successive small samples taken at suitable intervals of time.Velocity data from the earlier models were erratic and the permeability calibration did not include the range encountered in nature. In the Mark VI model, the standpipe is open during measurements of permeability. During measurement of groundwater velocity, the colour dilution chamber is completely sealed, colour is introduced and withdrawn through a sphincter valve with a hypodermic syringe. The solution is stirred during the period of dilution.The criteria of the measurements have been reconsidered. The standpipe, auxiliary equipment, and procedure have been redesigned, and the new model recalibrated. All this resulted in some loss of simplicity, but the data are consistent and accurate within 5%. The equipment is still simple and rugged enough for field examination of salmon spawning redds.Complete details of design, construction, and procedure, for use in salmon spawning gravels are given in Appendices.