Using ancient and recent soil properties to design a conceptual hydrological response model

- The soil morphology and chemistry in a hillslope was hydrologically interpreted.
- Processes identified by chemistry improved identification of hydrological processes.
- Soil morphological and chemical interpretations were confirmed by hydrometrics.
- Base cations and pH are important indicators of hydropedological processes.
- Three zones were identified by the chemistry; recharge, interflow and responsive.

Morphology (ancient) and chemistry (recent) were used as indicators of hydrological response and used to construct a conceptual hydrological response model with new insights into hydropedological interpretations of easily accessible soil data. Soil chemistry is hypothesised to be equilibrated with the recent water regime. Profiles of three soil types on the soilscape with descriptions, analyses, long-term soil water content and water tension data are discussed and 15 auger observations with descriptions and MIR data are used to develop a conceptual response model. Morphology was able to identify the primary response of soils. The deep interflow Cambisol on the midslope has a vertical flowpath through the first subsoil, indicated by the red apedal morphology, which combines with interflow in the second subsoil, indicated by stagnic colour patterns. The responsive Gleysol on the footslope is a storage mechanism, indicating permanently saturated conditions. The responsive Luvisol at the toeslope has interflow in the Albic horizon while the subsoils act as a storage mechanism. pH and base saturation were used to indicate leaching (flowpath), ferrolysis (fluctuating watertable), acid weathering and accumulation (water saturation). Iron and Mn were used as indicators of reducing conditions to infer the duration of saturation. Soil response was verified by water contents and tension data. Pedological processes were correlated to horizons and hydrological response. Chemistry was more sensitive to water regime change than soil morphology. Therefore soil chemistry was successfully used in designing a conceptual hydrological response model and improved identification of hydrological processes.