A geophysical analysis of hydro-geomorphic controls within a headwater wetland in a granitic landscape, through ERI and IP

Abstract

Abstract. Wetlands are undergoing considerable degradation in South Africa. As interventions are often technical and costly, there is a requirement to develop conceptual process models for these wetland systems so that rehabilitation attempts will be successful. This paper presents an approach using the geophysical methods of Electrical Resistivity Imaging (ERI) and Induced Polarization (IP) to delineate sub-surface hydro-geomorphic controls that maintain equilibrium disconnectivity of wetland-catchment processes, which through gully erosion are increasing the catchments connectivity through loss of water and sediment. The findings presented here give insight into the geomorphic processes that maintain the wetland in an un-degraded state, this allows for the development of a conceptual model outlining the wetland forming processes. The analysis suggests that sub-surface clay-plugs, within an otherwise sandy substrate are created by illuviation of clays from the surrounding hillslopes particularly at zones of valley confinement.

Hydropedological Classification of South African Hillslopes

“…Some hillslopes formed part of research catchments (e.g., Weatherley, Cathedral Peak VI and Two Streams) with detailed pedological and soil physical measurements and longterm hydrometric data available, whereas other hillslopes (e.g., Schmitsdrit and Bloemfontein) were surveyed morphologically with varied soil physical support measurements. Although the hillslopes in research catchments were integral to theory development and improved understanding of the interactive relationship between soil and hydrology (see, inter alia, Riddell et al (2010), van Tol et al (2010avan Tol et al ( , 2010bvan Tol et al ( , 2011, and Kuenene et al (2011)], the classiication of hillslopes in this study was based solely on results of hydropedological surveys of the hillslopes.…”

Geohydrodynamic properties of hydrogeological units in parts of Niger Delta, southern Nigeria

“…The dry season is a period of extreme aridity characterised by excruciating high temperatures that do reach 35°C. The area has been severely affected by the current global climatic changes in such a way that there have been shifts in both the upper and lower boundaries of these climatic conditions (Rapti-Caputo, 2010;Riddell et al, 2010;Wagner and Zeckhauser, 2011;Farauta et al, 2012).…”

Geoelectrohydrogeological indices of evidence of ingress of saline water into freshwater in parts of coastal aquifers of Ikot Abasi, southern Nigeria

“…The dry season is a period of extreme aridity characterized by excruciating high temperatures that do reach 35 °C. The area has been severely affected by the current global climatic changes in such a way that there have been shifts in both the upper and lower boundaries of these climatic conditions (Rapti-Caputo, 2010;Riddell et al 2010;Farauta, et al 2012George et al, 2015) Geologically, the study area is located in the Tertiary to Quaternary Coastal Plain Sands (CPS) (otherwise called the Benin Formation) and Alluvium environments of the Niger Delta region of southern Nigeria (Fig.1). The Benin Formation which is underlain by the Parallic Agbada Formation covers over 80% of the study area.…”