Improved hydropedological identification of soil salinity types in upland South Australia using seasonal trends in soil electrical conductivity

Abstract

Our hydropedological methods explain variations in seasonal changes during late winter (September) and late summer (April) to electrical conductivity (i.e. solute concentrations) in 19 near-surface (< 0.7 m) soil profile layers from a range of topographic settings within a 120 ha study area in the Mount Lofty Ranges, South Australia. By combining down profile trends of clay per cent, 1:5 water extractable cations and ions, and soil-landscape and terrain analysis patterns, we establish existence of four salinity types consistent with a new process-based salinity classification; two were associated with upper slope positions featuring perched watertables while the other two were associated with deep saline watertables, though in upper and lower landscape positions. Conceptual toposequence models for each salinity type explain the interactions between groundwater, soil morphology and landscape position. The methodology provides a convenient, costeffective adjunct to conventional groundwater approaches (e.g. nested piezometers) to determine patterns of water flow and solute transport in saline landscapes.