Journal cover Journal topic
Hydrology and Earth System Sciences An interactive open-access journal of the European Geosciences Union
doi:10.5194/hess-2016-640
© Author(s) 2016. This work is distributed
under the Creative Commons Attribution 3.0 License.
Research article
20 Dec 2016
Review status
This discussion paper is under review for the journal Hydrology and Earth System Sciences (HESS).
Understanding groundwater/surface-water interactions through hydropedological interpretation of soil distribution patterns
Johan van Tol Department of Soil Crop and Climate Sciences, University of the Free State, Bloemfontein, 9300, South Africa
Abstract. Understanding and quantifying groundwater/surface water interactions is important for effective water resource management. Characterisation of these interactions are however difficult due to heterogeneities in landscapes on difficulties in measuring hydrological processes at different scales. Although soils play an integral role in the hydrological functioning of landscape, very few groundwater/surface water interaction studies consider soils as key components of hydrologic variation. In this study, 21 catchments in South Africa with available stream attributes such as baseflow index (BFI) and an index of streamflow variability (CVB) were identified. The soils of the catchments were interpreted and grouped into four classes based on their dominant hydrological response namely: Recharge, Interflow, Responsive (shallow) and Responsive (wet). The dominant soil distribution patterns in the catchments were then determined. Significant positive correlation coefficients (r) exists between BFI and soil attributes such as depth (r = 0.72), clay content (r = 0.50) and percentage coverage by ‘Recharge’ soils (r = 0.78). The occurrence of "Interflow" and shallow soils decreased BFI significantly (r = −0.79 and −0.66 respectively). CVB are however positively correlated to the area of "Interflow" soils in the catchment (r = 0.73) and negatively to the area under "Recharge" soils (r = −0.65). Soils dominant in the valley bottom suggest that there are considerable differences in groundwater/surface water interaction mechanisms. Based on the results three perceptual models were constructed: (1) vertical drainage through soils and recharge of groundwater in the upper slopes of the catchment are dominant, with return flow to the soil in lower lying positions, both the soil and groundwater contribute the stream) (2) vertical drainage through soils and recharge of groundwater dominant in upper and lower lying positions, no return flow to soils, only groundwater contribute to stream and (3) lateral flow at soil bedrock is dominant throughout catchment, limited recharge, stream fed through lateral flow from soils with limited groundwater contribution.

Citation: van Tol, J.: Understanding groundwater/surface-water interactions through hydropedological interpretation of soil distribution patterns, Hydrol. Earth Syst. Sci. Discuss., doi:10.5194/hess-2016-640, in review, 2016.
Johan van Tol
Johan van Tol
Johan van Tol

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Short summary
Management of water resources requires a clear understanding of hydrological processes. Soils and soil distribution patterns governs and can serve as indicators of the dominant hydrological processes. In this study the soils and soil distribution patterns of 21 catchments in South Africa were interpreted and related to streamflow characteristics. The results show that the correct interpretation of soil information is of great value to understand hydrological processes.
Management of water resources requires a clear understanding of hydrological processes. Soils...
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