Geological significance of delineating paleochannels with AEM

Introduction

“…Neil Foley, Slawomir Tulaczyk, Esben Auken, Denys Grombacher, Jill Mikucki, Nikolaj Foged, Krista Myers, Hilary Dugan, Peter Doran, and Ross Virginia measure the thickness of permafrost in Antarctica and develop a heat-flow model to validate their results (Foley et al 2019). Less exotic, perhaps, but no less importantly, Subash Chandra, Joy Choudhury, Pradip K Maurya, Shakeel Ahmed, Esben Auken, and Saurabh K. Verma apply AEM to map palaeovalleys in India (Chandra et al 2019), while Andrea Viezzoli, Antonio Menghini, Nick Ebner, and Paul Hilliard take us back to the roots of AEM development in mineral exploration by looking for volcanic-hosted massive sulphides in Western Australia .…”

Airborne Electromagnetic Signatures of an Ancient River in the Water‐Stressed Ganga Plain, Prayagraj, India: A Potential Groundwater Repository

“…The ground based electrical and electromagnetic methods, though very effective for formation characterization with large scale applications, quite often are limited by various field constraints viz., inaccessible terrain, non-availability of suitable space and are time consuming. The airborne transient electromagnetics (AEM) investigations with ability to acquire large amount of closely spaced data at fast pace and relatively low cost, have been gaining increasing popularity globally for hydrogeological studies during the past few decades (Eberle & Siemon, 2006;Chandra et al, 2016;Chandra et al, 2020aChandra et al, , 2020bKnight et al, 2018;Siemon et al, 2009). In the recent past, the AEM with wide range of applications is established as a potential mapping tool to provide spatial distribution of aquifer structures (Viezzoli et al, 2008) sea water intrusion in coastal aquifers, aquifers below the ice cover (Dugan et al, 2014); network of bedrock fractures and groundwater pathways in crystalline hard rocks (Chandra et al, 2019).…”

“…There are limited applications of AEM for locating buried valley or paleochannels viz. buried valley in North-West German lowlands and Namib coastal plains (Eberle & Siemon, 2006); buried Quaternary valleys in islands of Denmark (Jørgensen et al, 2003) and paleochannel in parts of India (Chandra et al, 2020a(Chandra et al, , 2020b. Most of the studies mentioned above describe findings of paleo-valley in glacial environment except a study from India.…”

“…The paper also presents a discovery of a major buried paleoriver that can provide corridors for groundwater movement connecting aquifers as well as the Ganga and the Yamuna rivers. This information is also helpful in locating potential sites for groundwater recharge and discharge (Chandra et al, 2020a(Chandra et al, , 2020b and in assessing the factors controlling the base flow. Another major concern is the river water quality at Sangam, Prayagraj that has deteriorated with time (Sharma et al, 2014) and there is a pressing need to ensure supply of good quality water in the region.…”

“…Besides the aquifer, paleochannels are another very important subterranean features that act as aquifer corridors for groundwater movement, connecting many aquifer systems as well as potential sites for groundwater recharge and discharge (Rastogi et al, 2016;Valdiya, 2013). Paleochannel, once in contact with a contaminated source, can spread the contamination on a regional scale including deeper connected aquifer system (Chandra et al, 2020a(Chandra et al, , 2020b. Therefore, mapping of aquifer, paleochannels and their linkages assume significance in planning and management of groundwater resources.…”