Lab2: Modeling Sample Variogram
Geo597: Geostatistics
Spring 2011
Exercise
1. Choose data and interpolation method
In the "Geostatistical Wizard" window:
Choose "Kriging/CoKriging" in "Methods". Select the
appropriate "Source Dataset" and "Data Field" for "Dataset". -> Next.
2. Select kriging method
In the "Geostatistical Wizard: Kriging step 2 of 5" window:
(1) In the "Kriging Type" section, choose "Ordinary" as the
geostatistical method, then choose "Prediction" as the output.
(2) In the "Dataset #1" section, select the same "Transformation
type" as you
did when you normalized the histogram (Geostatistical Analyst -> Explore Data ->
Histogram). -> Next.
3. Model the sample variogram
In the "Geostatistical Wizard: Kring step 3 of 5 - Semivariogram/Covariance Modeling" window:
(1) In the "Semivariogram map" section, in "Show Search
Direction", choose "True", then experiment with the parameters of the semivariogram, "Angle
Direction", "Angle Tolerance", and "Bandwidth (lags)". Or you may interactively
change these parameters within the "Semivariogram/Covariance Surface" graph.
Complete assignments 1-4.
(2) In the "Models" section, try three different semivariogram models. Complete assignment
5.
4. Model the sample semivariogram with a single-structure model
(1) Model the anisotropic nature of the sample semivariogram, in “Anisotropy", choose "True" in the Models section. Multi-directional semivariogram models will appear in the "Semivariogram" section (keep the "Show Search Direction" box un-checked). Select an appropriate model from the model list to fit the sample semivariogram. Print the screen and complete assignment 6.
(2) Experiment with "Lag Size" and "Number of Lags", where
Lag-Size * Number-of-Lags <= 1/2 of the length or width of your study area.
Find out the distance of your study area by following ArcMap -> right click the
layer name -> Properties -> Source, then calculate the length/width based on the
"Top", "Left", "Right", and "Bottom" coordinates of your study area. Complete
assignment 7.
5. Model the sample semivariogram by a multi-structure model
For a two-structure semivariogram model, provide a "Partial Sill" for "Model 1", which should be less than the default partial sill, then check "Model 2", and then select a semivariogram model for model 2. Continue for "Model 3" if necessary. Complete assignment 8.
Assignment (Due: April 14)
6. Print single-structure, anisotropic semivariogram models.
7. Print single-structure anisotropic semivariogram models with customized lag size and number of lags.
8. Print multi-structure anisotropic semivariogram models.