Developing hydrological response models for selected soilscapes in the weatherly catchment, Eastern Cape Province
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Date
2013-07
Authors
Bouwer, Darren
Journal Title
Journal ISSN
Volume Title
Publisher
University of the Free State
Abstract
Soil acts as a first order control and determines the flowpaths of water exiting a catchment. The long
term interactive relationship between water and parent material has resulted in present soil
morphology. The soil chemical properties react faster than morphological properties to a change in
pedological processes predominantly controlled by the water regime in soil. Flowpath
characteristics, from very fast to very slow, determines the resultant soil chemistry. Soils can act as
flow 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 as
conduits of infiltrated water and recharge underlying fractured bedrock. Interflow soils were divided
into deep interflow and shallow-interflow responsive depending if the lateral movement of water
was in the deep subsoil or in an E horizon close to the surface. Responsive soils, due to the saturated
nature, will saturate quickly after infiltration inducing overland flow.
The soil chemical properties for representative profiles of a soilscape were described, characterised
and interpreted. Pedological processes were inferred from the soil morphology, chemical properties
and water regime measurements in soil profiles. Chemical properties were used to verify if the
morphological 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 chemical
property deductions.
A conceptual hydrological response model was constructed using soil morphology as an ancient
indicator of flow paths, which was improved using chemical properties as recent indicators of the
current water regime. The current water regime was verified with real time snapshots of hydrology
using hydrometric data.
Description
Keywords
Morphology, Chemical properties, Conceptual hydrological model, Flowpath, Storage mechanism, Hydrological models -- South Africa -- Eastern Cape, Watersheds, Dissertation (M.Sc. (Soil, Crop and Climate Sciences))--University of the Free State, 2013, Hydrological cycles