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I am trying to do interpolation in a coastal area with data points in several rivers emptying into a bay and on opposite sides of peninsulas. I have created a coastline layer to use it as a barrier but cannot figure out how to do this in ArcGIS 10. I do not see a barriers object anywhere in any of the kriging tools. I tried just doing the kriging then clipping it to the land, but I get unrealistic results where data points close together but separated by land create problems. I see online documentation for doing this in geoprocessing scripts in 9.3 but nothing similar for 10. Thanks so much!

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Just to add some links to view changes, compare documentation for ArcGIS 9.3 versus ArcGIS 10 –  Mike T Jun 19 '11 at 5:54
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4 Answers

Do the rivers run generally in a specific direction? If so, you could use directional binning along the centerlines of the rivers to constraint the empirical semivariograms only to point pairs running along the length of the rivers. (See here for more details: http://help.arcgis.com/en/arcgisdesktop/10.0/help/index.html#/Exploring_directional_autocorrelation/0031000000m2000000/)

Another option would by to partition the point samples into separate datasets and run your kriging on each set separately. This might be more appropriate anyway, since each river might have different statistical models to them; but would not work if your sample size is small for each river.

Do you need to use a geostatistical method, or would a deterministic method work? I think you might be able to achieve what you want using Diffusion Interpolation with Barriers. You could use your land as an extremely high cost barrier. http://help.arcgis.com/en/arcgisdesktop/10.0/help/index.html#//00310000002s000000.htm

Also, here is Diffusion Interpolation with absolute barriers as a geoprocessing script tool. Your coastline would make a perfect absolute barrier. http://help.arcgis.com/en/arcgisdesktop/10.0/help/index.html#/Diffusion_Interpolation_With_Barriers/003000000005000000/

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Have you tried the Topo to Raster tool? You can specify the type of the input features (Point Elevation, Stream, sink, contour, boundary, lake.) You could try setting your coast line layer features to "TopoLake"

Also, the result of the Topo to Raster tools is a "hydologically correct" raster

Quoting from Help: TopoLake A polygon feature class that specifies the location of lakes. All output raster cells within a lake will be assigned to the minimum elevation value of all cells along the shoreline.

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I believe that rather than constructing a representation of the topography, the OP wants to create a surface of measurements, such as of water quality, made within water bodies. Topo2Raster won't do that. (It doesn't Krige, either.) –  whuber Apr 18 '11 at 19:21
    
Yes, I am trying to do exactly that. –  elayne927 Apr 19 '11 at 15:53
    
You are absolutely right Bill, Topo to Raster does not allow for kriging. Just had the impression Elayne was referring to interpolation in general. (I often hear people lump all interpolation under kriging.) –  Jakub Apr 21 '11 at 12:54
    
Elayne, I think I know what you mean by unrealistic results. You could try converting your lakes into a grid of regularely spaced points with the lake's elevation value asigned to each point and adding it as input to the Topo to Raster tool as "Point elevation" This also will not yield a perfect result especially along the shoreline but will appear more realistic. Have you tried TIN and breaklines then converting the resulting TIN to raster? Can you post the link to the geoprocessing scripts you are referring to? –  Jakub Apr 21 '11 at 12:57
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I'm a late adopter so I can only tell you what works in 9.3 with the Spatial Analyst extension -- posting just in case the method still works in 10. First, create a closed linestring representing your area of interest (sounds like the inverse of your coastline here). Specify your "container" in the Spatial Analyst options dialog on the extent tab. Perform your analysis by selecting Kriging from the Interpolate to Raster in the Spatial Analyst menu.

Good luck!

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i think that you can use topo to raster tool and then use output extent for interpolating or use kriging then you use extract by mask tool for barrier . you should create a barrier layer (polygon layer) and then use extract by mask tool

sincerely

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The subtlety of this question is that masking and barriers work differently. A barrier eliminates certain points from the kriging neighborhoods, forcing the estimates to use only points that can be "seen" and not blocked by the barrier. This changes the results. Masking does not change the estimates, but merely restricts the interpolated map to the region defined by the mask. Unfortunately there is no post hoc way to obtain the estimates-with-barriers result from the estimates-without-barriers: you need the estimation procedure to have code for recognizing the barriers. –  whuber May 20 '11 at 17:25
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