Figure 58.  Observed semivariogram based on samples taken from a 1000 x 1000 test array using the planned sampling scheme. The semivariogram demonstrates that the number of samples at each lag distance (1-m interval) is sufficiently large to provide a strong pattern for fitting a model to the data. It also illustrates that influence of edge effects of the 1000-m x 1000-m ISA at about 800-m lag distance, preventing reliable evaluation of spatial structure beyond this distance.