Tracing shallow lateral preferential pathways of fluid movement using electrical geophysics

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 Ωm; 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.