- ISSN: 2202-0586
- E-ISSN:
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oa Tracing shallow lateral preferential pathways of fluid movement using electrical geophysics
- Australian Society of Exploration Geophysicists
- Source: ASEG Extended Abstracts, Volume 2018, Issue 1st Australasian Exploration Geoscience Conference – Exploration Innovation Integration, Dec 2018, p. 1 - 9
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- 01 Dec 2018
Abstract
Assessment of gullies is essential in understanding the effects soil erosion has on resource management, urban planning, agricultural productivity and local environmental conditions. Commonly, prediction of gully head cut retreat has been disregarded due to the inherent complexities; this study proposes a method of analysing data to interpret potential pathways of Gully retreat. Through the implementation of electrical geophysics (Electrical Resistivity Imaging & Frequency Domain Electromagnetics) surveys positioned uphill of existing gullies shallow conductor’s representative of Lateral Preferential Pathways (LPP) will be detected. ERI results detected conductors uphill of the head cut at varying distances showing resistivity values of 1 -40 Qm; these identified anomalous zones were confidently linked to form an LPP. Integrated geophysical datasets were generated allowing for interpreted traces of LPP to be drawn which are representative of the future pathway of head cut retreat. Through comparing currently existing gully assessment techniques it is suggested that a combination of geophysical prediction of LPP and LiDAR data is necessary for a complete understanding of existing gullies. Based on the results of this integration, informed and targeted management decisions can be developed to remediate current landforms and mitigate future gullying.
There has been recent focus placed on near surface groundwater and surface run-off flows as they have been attributed to erosion of consolidated and unconsolidated material resulting in incised surface channels referred to as gullies, which pose significant issues for agricultural productivity and local infrastructure (Beavis, 2000, Wu and Cheng, 2005). To effectively manage these erosional features through mitigation an understanding of the occurrence and future erosional pathways is required, although prediction is difficult when topographic variations are not obvious.
Local hydrological conditions will determine the nature of surface flows and groundwater movement including the infiltration depth, flow direction and rate of movement, although it is generally understood that water flows through physical or chemical channels known as preferential pathways (Clothier et al., 2007). Pathways develop within a medium due to the heterogeneities in the physical properties of the material that the water is flowing through.
