A statistical study of salinity and electrical resistivity of the active-layer soils along linear projects in Central Yakutia

Abstract

This study examined historical data sets from DC vertical electrical soundings performed for trunk gas pipeline projects in Central Yakutia and obtained characteristic values for salinity and resistivity of the active-layer soils. The results suggest that the correlation between these two parameters increases significantly and becomes stable in the metric of average median values. This makes it possible to derive, with different levels of generalization, direct and reverse petrophysical models both for theoretical understanding of the relationship between the two parameters and for practical calculation of average salinities from resistivity values. The absolute accuracy of salinity calculations is less than 0.1 % in 70 % of the cases, when resistivities averaged over 11 sounding points are introduced into the power function equations. The question of an optimal number of data points is left open and requires a special study for each case. It seems right to solve this problem at key sites of the terrain. The accuracy of salinity prediction with the regression equations is sufficient for rapid, cost-effective and environmentally safe solution to the problems of regional characterization and classification of permafrost terrain by active-layer salinity in the Central Yakutian lowland. Solving such problems before reconnaissance drilling is always important for engineering site investigations, as well as for soil salinity control and prediction in the agriculture.