Potenciometric models of Caiuá AquiferSystem in Paraná State northwest: comparision between ordinary kriging and co-kriging with external tendency from numeric terrain model.

Abstract

The hydrogeologic models provide evidence of morphological relation between topographic and potentiometric surfaces. The aim of this work was to quantify this relation from the interpolation of potentiometric and relief  data. Through static level height interpolation, using ordinary kriging and kriging with trend from the terrane numeric model (TNM), were created two potentiometric surface models of a free-aquifer (Caiuá Group arenites), located in the region located in coordinates 23°00’ and 24°00’ south and 52°30’and 54°00’ west. The data were supplied by Companhia de Saneamento do Paraná (Sanepar) and Superintendência de Desenvolvimento de Recursos Hídricos e de Saneamento Ambiental (Suderhsa), and refer to 230 flow wells. The techniques used for the interpolations involved a probing analysis of the data, which guided the construction of the variograms used in the following steps. After the interpolations, a comparative analysis of obtained results was made. This comparative analysis used the cross-validation technique, allowing us to associate the measured and calculated data for the same locations. Through qualitative and quantitative cross-validation results evaluation, it was concluded that the best results were obtained by kriging with trend from the TNM method, as compared to the ordinary kriging. The low density of sampling points made the variographic analysis and kriging more difficult, hindering the contemplation of geomorfological features important for the potentiometric surface control. Lastly, it was found that the selected potentiometric surface presents a similar morphology to the area landscape.