Geostatistical Modelling

The Zone of Influence

Often a variogram stops increasing beyond a certain distance (named the zone of influence) and remains more or less around a value (named the sill value). The zone of influence or range defines the distance in which the samples bear some kind of relationship to one another and beyond which samples are independent of one another, showing a random behaviour (Fig. 6a).

Figure 6a - Variogram with Range of Influence

In some instances, however, the range of influence may not exist (that is, variogram without a range), so that the further apart the samples, the higher is the variogram value (Fig. 6b).

Figure 6b - Variogram without Range of Influence