“Densify Sampling Network” – Error by reducing the monitoring network

MauriceWagner

Hello,

I am working on optimizing an existing monitoring well network in ArcGIS as part of my master thesis. I successfully used the tool “Densify Sampling Network” for adding measurement locations to parts of the study area with a high kriging standard error. However I can’t manage to use the tool for the reduction of measurement locations for those parts of the study area where they have the least influence on the predictions. I keep receiving "Error 040043: Measurement error for data with coincident samples should not be equal to zero." (As parameters I used number_output_points: 5 and in_candidate_point_features: point feature class containing all 137 monitoring wells). What am I doing wrong?

Thanks for your help in advance.

Best regards

Maurice

Eric6346

Hi Maurice,

Unfortunately, the workflow for removing points from an existing network requires that the nugget parameter in kriging be interpreted at least partially as measurement error.  I will add this limitation to the documentation for Densify Sampling Network.

To resolve the error, you need to alter one parameter of your kriging layer using the following steps:

1. Optionally, make a copy of your kriging layer in case you make a mistake.
2. Right-click the kriging layer in Table of Contents and choose "Method Properties".  This will open the Geostatistical Wizard and allow you to change parameters for that kriging layer.
3. Click Next until you get to the Semivariogram/Covariance modeling page.
4. In the parameters on the right, find "Measurement Error" (it is under the "Model Nugget" menu).  To encounter Error 040043, this parameter must have been set to 0 (if it is any other value, please let me know).
5. Change the Measurement Error value to anything larger than 0 but no larger than 100.
6. Click Finish, then OK on the Method Report screen.  This will update the kriging layer, but it will probably look identical in the map.
7. Re-run Densify Sampling Network with the altered kriging layer, and it should now run successfully.

Please let me know if you have any other questions or run into any other problems.

-Eric Krause, Geostatistical Analyst Product Engineer

PS, if you intended to remove 5 points from your network, you should actually use 132 for the number_output_points rather than 5.  The five points that are not created by the tool are the stations that can be most safely removed; the 132 points that are created from the tool are the ones that help the most in the interpolation.

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