A simple device for measuring differences in hydraulic head between surface water and shallow ground water

This fact sheet describes a simple device for measuring the vertical hydraulic gradient (VHG) of shallow ground water beneath a stream bed. The VHG can be used to determine whether a stream is receiving or losing water at the point of measurement. Used as part of a spatial or temporal survey, such measurements can yield valuable information about the local hydrology of a stream/ground-water system. This device also can be used to withdraw shallow subsurface water for chemical analyses. The device is inexpensive and lightweight, but lacks the precision and range of measurement of other probes, such as those described by Winter and others (1988) and Duff and others (1998).