The two most popular scales are arithmetic and semi-logarithmic (semi-log).

Todd (1959) states that the semilog method is valid for u < 0.01.

Figure 8.24 (a) Determination of T and S from h0 – h versus t data using the semilog method; (b) semilog plot in the vicinity of an impermeable boundary.

Figure 8.24 (a) Determination of T and S from h0 – h versus t data using the semilog method; (b) semilog plot in the vicinity of an impermeable boundary.

The first involves curve matching on a log-log plot (the Theis method), and the second involves interpretations with a semilog plot (the Jacob method).

The semilog method is very well suited to the analysis of bounded confined aquifers.

Figure 8.24(a) shows the time-drawdown data of Figure 8.22 plotted on a semilog graph.

A semi-log graph is a graph with one axis using a linear scale and one axis using a logarithmic scale.

Note: Semi-logarithmic graph paper refers to a grid where one axis is plotted using a logarithmic scale and the other axis uses a linear scale.

A log graph, formally known as a semi-logarithmic graph, is a graph that uses a linear scale on one axis and a logarithmic scale on the other axis.

The initial results for a regression using OLS with a semi-log functional form for a single year (2008) are summarised in Table 11.6.

On a semi-log chart, however, the 100% gain ($5 to $10) would occupy a much larger portion of the chart, as opposed to the 4% increase of the $120 to $125 move.

The curve that best overlaps with the log law portion of the measured velocity profile on the semi-log plots gives the value of the measured skin friction coefficient.