ABSTRACT
The depth of the water table in a well is measured relative to an agreed-upon mark at the top, for example, the edge of the casing. This reference point should be clearly marked to ensure reproducibility of the measurements. The depth of the water table is obtained in meters below the top of the well or, more meaningfully, in meters below the surface, as shown in Fig. 4.1. AC is the depth of the water table below the reference mark at the edge of the well casing (or any other selected mark). This might differ slightly from BC, the depth of the water table below the surface (Fig. 4.1). In the field notebook the depth AC should be used, as it is exact and properly defined. In a final report reference to the surface may be preferred. In any case, one has to specify how the depth is expressed: “below well head” or “below surface.”
