airborne electromagnetic
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Geosciences ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. 26
Author(s):  
Philipp O. Kotowski ◽  
Michael Becken ◽  
Anneke Thiede ◽  
Volkmar Schmidt ◽  
Jörg Schmalzl ◽  
...  

The semi-airborne electromagnetic (EM) method has the potential to reach deeper exploration depths than purely airborne EM approaches. The concept of the method is to deploy high-power transmitters on the ground, which excite subsurface currents and induce strong magnetic fields, and to measure the corresponding EM fields with a passive airborne receiver instrument. Following recent conceptual developments of the semi-airborne EM technique deployed on helicopters, we performed a 10 km2 semi-airborne EM survey near Münster (Germany) based on a multicopter aircraft system. For this purpose, horizontal electric dipole (HED) transmitters were installed in the survey area and were surveyed individually. Magnetic transfer functions were determined and a model of the conductivity of the study area was derived. Despite restrictions such as low payload capacity and multicopter-related EM noise, we were able to estimate spatially and spectrally consistent transfer functions of high quality up to a distance of 2 km from the respective transmitter. Our results could be validated with independent results from a magnetotelluric and a direct current sounding. The study demonstrates that an unmanned aircraft system (UAS) is suitable for semi-airborne EM application and that such a system can be beneficial where ground-based methods and manned techniques become impractical.


2022 ◽  
pp. 104541
Author(s):  
Yiming He ◽  
Weiying Chen ◽  
Kangxin Lei ◽  
Yang Zhao ◽  
Pengfei Lv

Author(s):  
Subash Chandra ◽  
Virendra M. Tiwari ◽  
Mulavada Vidyasagar ◽  
Kattula B. Raju ◽  
Joy Choudhury ◽  
...  

2021 ◽  
Vol 13 (22) ◽  
pp. 4687
Author(s):  
Edward J. Harrison ◽  
Vikas C. Baranwal ◽  
Andreas A. Pfaffhuber ◽  
Craig W. Christensen ◽  
Guro H. Skurdal ◽  
...  

From the first use of airborne electromagnetic (AEM) systems for remote sensing in the 1950s, AEM data acquisition, processing and inversion technology have rapidly developed. Once used extensively for mineral exploration in its early days, the technology is increasingly being applied in other industries alongside ground-based investigation techniques. This paper reviews the application of onshore AEM in Norway over the past decades. Norway’s rugged terrain and complex post-glacial sedimentary geology have contributed to the later adoption of AEM for widespread mapping compared to neighbouring Nordic countries. We illustrate AEM’s utility by using two detailed case studies, including time-domain and frequency domain AEM. In both cases, we combine AEM with other geophysical, geological and geotechnical drillings to enhance interpretation, including machine learning methods. The end results included bedrock surfaces predicted with an accuracy of 25% of depth, identification of hazardous quick clay deposits, and sedimentary basin mapping. These case studies illustrate that although today’s AEM systems do not have the resolution required for late-phase, detailed engineering design, AEM is a valuable tool for early-phase site investigations. Intrusive, ground-based methods are slower and more expensive, but when they are used to complement the weaknesses of AEM data, site investigations can become more efficient. With new developments of drone-borne (UAV) systems and increasing investment in AEM surveys, we see the potential for continued global adoption of this technology.


2021 ◽  
Author(s):  
Marina G. Persova ◽  
Yury G. Soloveichik ◽  
Denis V. Vagin ◽  
Dmitry S. Kiselev ◽  
Anastasia P. Sivenkova ◽  
...  

Grundwasser ◽  
2021 ◽  
Author(s):  
Eva González ◽  
Nico Deus ◽  
Jörg Elbracht ◽  
M. Azizur Rahman ◽  
Helga Wiederhold

AbstractSalinization of the upper aquifer of the northern Elbe-Weser region almost extends to the surface. Chloride content exceeds 250 mg/l and the groundwater is therefore, according to the German Drinking Water Ordinance, not suitable as drinking water. The chloride content in the aquifer originates from early flooding with seawater which occurred during the Holocene sea level rise. Depth and extent of the salinization were mapped by airborne electromagnetic surveys and validated by groundwater analyses. In the transition zone between the marshlands and geest areas, the fresh-saline groundwater interface falls to a depth of > −175 m NHN. Due to the extensive drainage of the marshlands, seepage of fresh groundwater is impeded. Instead, an upconing of the fresh-saline groundwater interface appears due to an upwardly directed hydraulic gradient. Due to climate change, chloride concentrations will increase along the coastlines. Further inland, a decrease of chloride content in near-surface groundwater will occur.


Author(s):  
Marina G. Persova ◽  
Yuri G. Soloveichik ◽  
Denis V. Vagin ◽  
Dmitry S. Kiselev ◽  
Anastasia P. Sivenkova ◽  
...  

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