Spatial relationship of the saturated hydraulic conductivity and rock fragments on the soil surface in an Andean microwatershed

Abstract

Saturated hydraulic conductivity (Ks) is an important soil variable. Multiple investigations have analysed the influence of rock fragments on saturated hydraulic conductivity, but they hardly involve the spatial component. This research spatially modelled the Ks and its relationship with the contents of rock fragments, organic carbon, and total porosity in the surface horizon of the soils of a tropical Andean micro-basin. Hydrologic response units were used to run a stratified-type sampling. Ks was determined using the constant head method and the total porosity using the tension table. Disturbed samples were used to determine rock fragments and organic carbon content. Results showed that the Ks had an exponential distribution, with high values located in areas of the middle and upper parts of the basin. The distribution was spatially related to the content of rock fragments, the total porosity and the organic carbon content using the spatial autocorrelation model with which it was obtained the best fit results between the observed values of Ks and their predicted values on the soil surface (r = 0.883). The inclusion of these three variables in pedotransfer functions and hydrological models would reduce the uncertainty in estimating the saturated flow of soil water in stony soils.