Developing hydrological response models for selected soilscapes in the weatherly catchment, Eastern Cape Province

[摘要] Soil acts as a first order control and determines the flowpaths of water exiting a catchment. The longterm interactive relationship between water and parent material has resulted in present soilmorphology. The soil chemical properties react faster than morphological properties to a change inpedological processes predominantly controlled by the water regime in soil. Flowpathcharacteristics, from very fast to very slow, determines the resultant soil chemistry. Soils can act asflow path or as a storage mechanism of water in the soilscape.Soils were grouped according to their hydrological response. Recharge soils are soils, which serve asconduits of infiltrated water and recharge underlying fractured bedrock. Interflow soils were dividedinto deep interflow and shallow-interflow responsive depending if the lateral movement of waterwas in the deep subsoil or in an E horizon close to the surface. Responsive soils, due to the saturatednature, will saturate quickly after infiltration inducing overland flow.The soil chemical properties for representative profiles of a soilscape were described, characterisedand interpreted. Pedological processes were inferred from the soil morphology, chemical propertiesand water regime measurements in soil profiles. Chemical properties were used to verify if themorphological properties are in phase with the current water regime. Annual duration of saturation(ADs>o.7),which is defined as 70% saturation of porosity was also used to support the chemicalproperty deductions.A conceptual hydrological response model was constructed using soil morphology as an ancientindicator of flow paths, which was improved using chemical properties as recent indicators of thecurrent water regime. The current water regime was verified with real time snapshots of hydrologyusing hydrometric data.

[发布机构] University of the Free State