Details zur Publikation |
| Kategorie | Textpublikation |
| Referenztyp | Zeitschriften |
| DOI | 10.5194/hess-27-3059-2023 |
Lizenz  |
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| Titel (primär) | A change in perspective: downhole cosmic-ray neutron sensing for the estimation of soil moisture |
| Autor | Rasche, D.; Weimar, J.; Schrön, M.; Köhli, M.; Morgner, M.; Güntner, A.; Blume, T. |
| Quelle | Hydrology and Earth System Sciences |
| Erscheinungsjahr | 2023 |
| Department | MET |
| Band/Volume | 27 |
| Heft | 16 |
| Seite von | 3059 |
| Seite bis | 3082 |
| Sprache | englisch |
| Topic | T5 Future Landscapes |
| Abstract | Above-ground cosmic-ray neutron sensing (CRNS) allows for the non-invasive estimation of the
field-scale soil moisture content in the upper decimetres of the soil. However,
large parts of the deeper vadose zone remain outside of its observational
window. Retrieving soil moisture information from these deeper layers requires
extrapolation, modelling or other methods, all of which come with
methodological challenges. Against this background, we investigate CRNS for
downhole soil moisture measurements in deeper layers of the vadose zone. To
render calibration with in situ soil moisture measurements unnecessary, we
rescaled neutron intensities observed below the terrain surface with
intensities measured above a waterbody. An experimental set-up with a CRNS sensor deployed at different depths of up to 10 m below the surface in a groundwater observation well combined with particle transport simulations revealed the response of downhole thermal neutron intensities to changes in the soil moisture content at the depth of the downhole neutron detector as well as in the layers above it. The simulation results suggest that the sensitive measurement radius of several decimetres, which depends on soil moisture and soil bulk density, exceeds that of a standard active neutron probe (which is only about 30 cm). We derived transfer functions to estimate downhole neutron signals from soil moisture information, and we describe approaches for using these transfer functions in an inverse way to derive soil moisture from the observed neutron signals. The in situ neutron and soil moisture observations confirm the applicability of these functions and prove the concept of passive downhole soil moisture estimation, even at larger depths, using cosmic-ray neutron sensing. |
| dauerhafte UFZ-Verlinkung | https://www.ufz.de/index.php?en=20939&ufzPublicationIdentifier=27889 |
| Rasche, D., Weimar, J., Schrön, M., Köhli, M., Morgner, M., Güntner, A., Blume, T. (2023): A change in perspective: downhole cosmic-ray neutron sensing for the estimation of soil moisture Hydrol. Earth Syst. Sci. 27 (16), 3059 - 3082 10.5194/hess-27-3059-2023 |
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