Geostatistical Approach to Spatial Data Transformation

Author(s):  
Eun-Hye Yoo
Water ◽  
2021 ◽  
Vol 13 (22) ◽  
pp. 3269
Author(s):  
Marianna Cangemi ◽  
Valentina Censi ◽  
Paolo Madonia ◽  
Rocco Favara

Sources of groundwater contaminants in inhabited areas, located in complex geo-tectonic contexts, are often deeply interlocked, thus, making the discrimination between anthropic and natural origins difficult. In this study, we investigate the Peloritani Mountain aquifers (Sicily, Italy), using the combination of probability plots with concentration contour maps to retrieve an overall view of the groundwater geo-chemistry with a special focus on the flux of heavy metals. In particular, we present a methodology for integrating spatial data with very different levels of precision, acquired before and during the “geomatic era”. Our results depict a complex geochemical layout driven by a geo-puzzle of rocks with very different lithological natures, hydraulically connected by a dense tectonic network that is also responsible for the mixing of deep hydrothermal fluids with the meteoric recharge. Moreover, a double source, geogenic or anthropogenic, was individuated for many chemicals delivered to groundwater bodies. The concentration contour maps, based on the different data groups identified by the probability plots, fit the coherency and congruency criteria with the distribution of both rock matrices and anthropogenic sources for chemicals, indicating the success of our geostatistical approach.


Geosciences ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 196
Author(s):  
Emmanouil A. Varouchakis

Data gaussianity is an important tool in spatial statistical modeling as well as in experimental data analysis. Usually field and experimental observation data deviate significantly from the normal distribution. This work presents alternative methods for data transformation and revisits the applicability of a modified version of the well-known Box-Cox technique. The recently proposed method has the significant advantage of transforming negative sign (fluctuations) data in advance to positive sign ones. Fluctuations derived from data detrending cannot be transformed using common methods. Therefore, the Modified Box-Cox technique provides a reliable solution. The method was tested in average rainfall data and detrended rainfall data (fluctuations), in groundwater level data, in Total Organic Carbon wt% residuals and using random number generator simulating potential experimental results. It was found that the Box-Cox technique competes successfully in data transformation. On the other hand, it improved significantly the normalization of negative sign data or fluctuations. The coding of the method is presented by means of a Graphical User Interface format in MATLAB environment for reproduction of the results and public access.


2017 ◽  
Vol 8 (2) ◽  
pp. 594-599 ◽  
Author(s):  
A. Castrignanò ◽  
R. Quarto ◽  
A. Venezia ◽  
G. Buttafuoco

The paper proposes a geostatistical framework to solve the issues of heterogeneous support for spatial estimation. Apparent soil electrical conductivity (ECa) was measured in a field cropped with San Marzano tomato using a multiple frequency electromagnetic profiler with 6 operating frequencies. Mixed support kriging was used to estimate ECa taking into account the change of support. The method includes punctual kriging with the error being the dispersion variance associated with each frequency. The individual ECa maps were weighted by the dispersion variance to obtain a map which was used for field partition in management zones.


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