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It´s in the geomorphological point of view, but i named fines to the <0.063 mm particles, representing the same as the %clay/silt. I want to obtain a smooth sediment map and the respective error, for this i am doing the kriging. I do not want to make a classification map,
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10-29-2015
10:34 AM
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I separate the sediment into three major components: fines, sand and gravel. For now, i'm trying to interpolate fines and gravel content separately. I agree with you that near to this rock outcrop exists more removal and this is showed by the low content of fines in that area, but in some of this sites this not correspond, as expected, to high % of gravel. It seems quite strange the absence of gravel near of some location with high content.
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10-29-2015
08:54 AM
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I forget to mention that in the graphic the values are in the logit scale.
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10-29-2015
07:43 AM
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I'm using kriging, so i think that this works better with normal distributed data. Am i wrong? As i told before, i already interpolate the fines content and it´s easy to understand its spatial distribution, high values in deeper areas and in front of major rivers. However, in the gravel content case i have some difficulties to understand. I believe that the high values correspond to historical deposits of gravel. The topography is quite monotonous, as you can see in the figure (now with the bathymetric lines ranging from 20 to 200 m), the only relevant feature is the rock outcrop highlighted with the arrow. One of my questions is that if i could present in a thesis a surface with this cross validation results (graphic bellow)? I could not make it much better, i think due to that distribution values (0% near to >50%).
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10-29-2015
07:42 AM
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Hi Dan, thank you for the help. The zero points data are real and valid measurements. I try a wide range of transformations aiming to normalize the data because is skewed, but this seems to be impossible due to the high number of zeros. I post a figure with the spatial distribution of my data.
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10-29-2015
03:51 AM
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Hi everyone, i am trying to interpolate the seabed sediment gravel content and i experience some problems in the cross-validation results, like the slope of the graph predicted vs. measured is not bigger than 0.6 with some hi errors. However, analyzing the layer obtained, this one seems good. I think that the problem it maybe related with the high number of zeros, 92 in 226 samples. I already transform the variable with square root, 4th root, log (x + 0.0001), logit (x + 0.0001) and normal score transformation included in ArcGIS, but the problem persists. I already make an interpolation for other variable quite similar to this using the logit, namely the fines content, and it went well. I´m asking why i could not make a good interpolation in the case of the gravel content? Maybe the large number of zeros? Or it could be related to the inherent variability to this variable vs. sampling resolution? Someone could help me with this problem? Thank you in advance.
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10-28-2015
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Hello, i want to cut a rectangular shapefile with a coast line (belonging to a shapefile) and a bathymetric line. Someone can help me in this task? Thank you
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