HESS Hydrology and Earth System Sciences HESS Hydrol. Earth Syst. Sci. 1607-7938 Copernicus Publications Göttingen, Germany 10.5194/hess-19-225-2015 Monitoring hillslope moisture dynamics with surface ERT for enhancing spatial significance of hydrometric point measurements Hübner R. 1 Heller K. 1 Günther T. https://orcid.org/0000-0001-5409-0273 2 Kleber A. 1 Institute of Geography, Dresden University of Technology, Helmholtzstr. 10, 01069 Dresden, Germany Leibniz Institute for Applied Geophysics (LIAG), Stilleweg 2, 30655 Hanover, Germany 14 01 2015 19 1 225 240 Copyright: © 2015 R. Hübner et al. 2015 This work is licensed under the Creative Commons Attribution 3.0 Unported License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/3.0/ This article is available from https://hess.copernicus.org/articles/19/225/2015/hess-19-225-2015.html The full text article is available as a PDF file from https://hess.copernicus.org/articles/19/225/2015/hess-19-225-2015.pdf

Besides floodplains, hillslopes are basic units that mainly control water movement and flow pathways within catchments of subdued mountain ranges. The structure of their shallow subsurface affects water balance, e.g. infiltration, retention, and runoff. Nevertheless, there is still a gap in the knowledge of the hydrological dynamics on hillslopes, notably due to the lack of generalization and transferability. This study presents a robust multi-method framework of electrical resistivity tomography (ERT) in addition to hydrometric point measurements, transferring hydrometric data into higher spatial scales to obtain additional patterns of distribution and dynamics of soil moisture on a hillslope. A geoelectrical monitoring in a small catchment in the eastern Ore Mountains was carried out at weekly intervals from May to December 2008 to image seasonal moisture dynamics on the hillslope scale. To link water content and electrical resistivity, the parameters of Archie's law were determined using different core samples. To optimize inversion parameters and methods, the derived spatial and temporal water content distribution was compared to tensiometer data. The results from ERT measurements show a strong correlation with the hydrometric data. The response is congruent to the soil tension data. Water content calculated from the ERT profile shows similar variations as that of water content from soil moisture sensors. Consequently, soil moisture dynamics on the hillslope scale may be determined not only by expensive invasive punctual hydrometric measurements, but also by minimally invasive time-lapse ERT, provided that pedo-/petrophysical relationships are known. Since ERT integrates larger spatial scales, a combination with hydrometric point measurements improves the understanding of the ongoing hydrological processes and better suits identification of heterogeneities.

 References AD-hoc AG-Boden: Bodenkundliche Kartieranleitung, 5th Edn., Bundesanst. für Geowiss. und Rohstoffe in Zusammenarb. mit den Staatl. Geol. Diensten, Hannover, 2005. Amoozegar, A.: A compact constant-head permeameter for measuring saturated hydraulic conductivity of the Vadose Zone, Soil Sci. Soc. Am. J., 53, 1356–1361, 1989. Anderson, M. G. and Burt, T. P. (Eds.): Process studies in hillslope hydrology, Wiley, Chichester, West Sussex, England, New York, 1990. Apparao, A.: Geoelectric profiling, Geoexploration, 27, 351–389, 1991. Archie, G.: The electrical resistivity log as an aid in determining some reservoir characteristics, T. Am. I. Min. Met. Eng., 146, 54–61, 1942. Barker, R.: Depth of investigation of collinear symmetrical four-electrode arrays, Geophysics, 54, 1031–1037, 1989. Bechtold, M., Vanderborght, J., Weihermueller, L., Herbst, M., Günther, T., Ippisch, O., Kasteel, R., and Vereecken, H.: Upward transport in a three-dimensional heterogeneous laboratory soil under evaporation conditions, Vadose Zone J., 11, <a href="http://dx.doi.org/10.2136/vzj2011.0066">https://doi.org/10.2136/vzj2011.0066</a>, 2012. Beff, L., Günther, T., Vandoorne, B., Couvreur, V., and Javaux, M.: Three-dimensional monitoring of soil water content in a maize field using Electrical Resistivity Tomography, Hydrol. Earth Syst. Sci., 17, 595–609, <a href="http://dx.doi.org/10.5194/hess-17-595-2013">https://doi.org/10.5194/hess-17-595-2013</a>, 2013. Benderitter, Y. and Schott, J. J.: Short time variation of the resistivity in an unsaturated soil: the relationship with rainfall, Eur. J. Environ. Eng. Geophys., 4, 37–49, 1999. Binley, A., Henry-Poulter, S., and Shaw, B.: Examination of solute transport in an undisturbed soil column using electrical resistance tomography, Water Resour. Res., 32, 763–769, 1996a. Binley, A., Shaw, B., and Henry-Poulter, S.: Flow pathways in porous media: electrical resistance tomography and dye staining image verification, Meas. Sci. Technol., 7, 384–390, 1996b. Brunet, P., Clément, R., and Bouvier, C.: Monitoring soil water content and deficit using Electrical Resistivity Tomography (ERT) a case study in the Cevennes area, France, J. Hydrol., 48, 146–153, 2010. Cassiani, G., Bruno, V., Villa, A., Fusi, N., and Binley, A.: A saline trace test monitored via time-lapse surface electrical resistivity tomography, J. Appl. Geophys., 59, 244–259, 2006. Cassiani, G., Godio, A., Stocco, S., Villa, A., Deiana, R., Frattini, P., and Rossi, M.: Monitoring the hydrologic behaviour of a mountain slope via time-lapse electrical resistivity tomography, Near Surf. Geophys., 7, 475–486, 2009. Chifflard, P., Didszun, J., and Zepp, H.: Skalenübergreifende Prozess-Studien zur Abflussbildung in Gebieten mit periglazialen Deckschichten (Sauerland, Deutschland), Grundwasser, 13, 27–41, 2008. Dahlin, T. and Zhou, B.: A numerical comparison of 2-D resistivity imaging with 10 electrode arrays, Geophys. Prospect., 52, 379–398, 2004. Daily, W., Ramirez, A., LaBrecque, D. J., and Nitao, J.: Electrical resistivity tomography of vadose water movement, Water Resour. Res., 28, 1429–1442, 1992. De Morais, F., De Almeida Prado Bacellar, L., and Aranha, P. R. A.: Study of flow in vadose zone from electrical resistivity surveys, Rev. Bras. Geofis., 26, 115–122, 2008. Descloitres, M., Ribolzi, O., and Le Troquer, Y.: Study of infiltration in a Sahelian gully erosion area using time-lapse resistivity mapping, Catena, 53, 229–253, 2003. Descloitres, M., Ribolzi, O., Troquer, Y. L., and Thiébaux, J. P.: Study of water tension differences in heterogeneous sandy soils using surface ERT, J. Appl. Geophys., 64, 83–98, 2008a. Descloitres, M., Ruiz, L., Sekhar, M., Legchenko, A., Braun, J., Mohan Kumar, M. S., and Subramanian, S.: Characterization of seasonal local recharge using electrical resistivity tomography and magnetic resonance sounding, Hydrol. Process., 22, 384–394, 2008b. Di Baldassarre, G. and Uhlenbrook, S.: Is the current flood of data enough? A treatise on research needs for the improvement of flood modelling, Hydrol. Process., 26, 153–158, 2012. French, H. and Binley, A.: Snowmelt infiltration: monitoring temporal and spatial variability using time-lapse electrical resistivity, J. Hydrol., 297, 174–186, 2004. Garré, S., Koestel, J., Günther, T., Javaux, M., Vanderborght, J., and Vereecken, H.: Comparison of heterogeneous transport processes observed with electrical resistivity tomography in two soils, Vadose Zone J., 9, 336–349, 2010. Garré, S., Javaux, M., Vanderborght, J., Pages, L., and Vereecken, H.: Three-dimensional electrical resistivity tomography to monitor root zone water dynamics, Vadose Zone J., 10, 412–424, 2011. Günther, T., Rücker, C., and Spitzer, K.: Three-dimensional modelling and inversion of dc resistivity data incorporating topography – II. Inversion, Geophys. J. Int., 166, 506–517, 2006. Hayashi, M.: Temperature-electrical conductivity relation of water for environmental monitoring and geophysical data inversion, Environ. Monit. Assess., 96, 119–128, 2004. Heller, K.: Einfluss periglazialer Deckschichten auf die oberflächennahen Fließwege am Hang – eine Prozessstudie im Osterzgebirge, Sachsen, Ph.D. thesis, Faculty of Environmental Sciences, TU Dresden, available at: <a href="http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-98437">http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-98437</a> (last access: 30 April 2014), 2012. Keller, G. V. and Frischknecht, F. C.: Electrical Methods in Geophysical Prospecting, Pergamon Press, Oxford, 1966. Kemna, A., Vanderborght, J., Hardelauf, H., and Vereecken, H.: Quantitative imaging of 3-D solute transport using 2-D time-lapse ERT: a synthetic feasibility study, in: 17th EEGS Symposium on the Application of Geophysics to Engineering and Environmental Problems, Colorado, USA, 342–353, 2004. Kirkby, M. J. (Ed.): Hillslope Hydrology, Wiley, Chichester, 1980. Kleber, A.: Lateraler Wasserfluss in Hangsedimenten unter Wald, in: Stoff- und Wasserhaushalt in Einzugsgebieten, Beiträge zur EU-Wasserrahmenrichtlinie, edited by: Lorz, C. and Haase, D., Springer Verlag, Heidelberg, 7–22, 2004. Kleber, A. and Schellenberger, A.: Slope hydrology triggered by cover-beds, With an example from the Frankenwald Mountains, northeastern Bavaria, Z. Geomorphol., 42, 469–482, 1998. Kleber, A. and Terhorst, B. (Eds.): Mid-Latitude Slope Deposits (Cover Beds), vol. 66 of Developments in sedimentology, 1st Edn., Elsevier, Amsterdam, Boston, Heidelberg, London, New York, Oxford, Paris, San Diego, San Francisco, Singapore, Sydney, Tokyo, 2013. Klute, A. (Ed.): Methods of Soil Analysis, Part 1: Physical and Mineralogical Methods, 2nd Edn., ASA, SSA, Madison, Wisconsin, 1986. Koestel, J., Kemna, A., Javaux, M., Binley, A., and Vereecken, H.: Quantitative imaging of solute transport in an unsaturated and undisturbed soil monolith with 3-D ERT and TDR, Water Resour. Res., 44, W12411, <a href="http://dx.doi.org/10.1029/2007WR006755">https://doi.org/10.1029/2007WR006755</a>, 2008. Koestel, J., Vanderborght, J., Javaux, M., Kemna, A., Binley, A., and Vereecken, H.: Noninvasive 3-D transport characterization in a sandy soil using ERT: 1. Investigating the validity of ERT-derived transport parameters, Vadose Zone J., 8, 711–722, 2009a. Koestel, J., Vanderborght, J., Javaux, M., Kemna, A., Binley, A., and Vereecken, H.: Noninvasive 3-D transport characterization in a sandy soil using ERT: 2. Transport process inference, Vadose Zone J., 8, 723–734, 2009b. Kuras, O., Pritchard, J. D., Meldrum, P. I., Chambers, J. E., Wilkinson, P. B., Ogilvy, R. D., and Wealthall, G. P.: Monitoring hydraulic processes with automated time-lapse electrical resistivity tomography (ALERT), CR Geosci., 341, 868–885, 2009. LaBrecque, D. J., Miletto, M., Daily, W., Ramirez, A., and Owen, E.: The effects of noise on Occam's inversion of resistivity tomography data, Geophysics, 61, 538–548, 1996. Leslie, I. N. and Heinse, R.: Characterizing soil-pipe networks with pseudo-three-dimensional resistivity tomography on forested hillslopes with restrictive horizons, Vadose Zone J., 12, <a href="http://dx.doi.org/10.2136/vzj2012.0200">https://doi.org/10.2136/vzj2012.0200</a>, 2013. Lesmes, D. P. and Friedman, S. P.: Relationships between the electrical and hydrogeological properties of rocks and soils, in: Hydrogeophysics, edited by: Rubin, Y. and Hubbard, S. S., Springer, Dordrecht, 87–128, 2006. Ma, R., McBratney, A., Whelan, B., Minasny, B., and Short, M.: Comparing temperature correction models for soil electrical conductivity measurement, Precis. Agric., 12, 55–66, 2011. Massuel, S., Favreau, G., Descloitres, M., Le Troquer, Y., Albouy, Y., and Cappelaere, B.: Deep infiltration through a sandy alluvial fan in semiarid Niger inferred from electrical conductivity survey, vadose zone chemistry and hydrological modelling, Catena, 67, 105–118, 2006. McDonnell, J. J.: Where does water go when it rains? Moving beyond the variable source area concept of rainfall–runoff response, Hydrol. Process., 17, 1869–1875, 2003. McDonnell, J. J., Tanaka, T., Mitchell, M. J., and Ohte, N.: Hydrology and biogeochemistry of forested catchments, Hydrol. Process., 15, 1673–1674, 2001. McDonnell, J. J., Sivapalan, M., Vaché, K., Dunn, S., Grant, G., Haggerty, R., Hinz, C., Hooper, R., Kirchner, J., Roderick, M. L., Selker, J., and Weiler, M.: Moving beyond heterogeneity and process complexity: a new vision for watershed hydrology, Water Resour. Res., 43, W07301, <a href="http://dx.doi.org/10.1029/2006WR005467">https://doi.org/10.1029/2006WR005467</a>, 2007. Michot, D., Benderitter, Y., Dorigny, A., Nicoullaud, B., King, D., and Tabbagh, A.: Spatial and temporal monitoring of soil water content with an irrigated corn crop cover using surface electrical resistivity tomography, Water Resour. Res., 39, SBH 14-1–SBH 14-20, 2003. Miller, C. R., Routh, P. S., Brosten, T. R., and McNamara, J. P.: Application of time-lapse ERT imaging to watershed characterization, Geophysics, 73, G7–G17, 2008. Moldenhauer, K.-M., Heller, K., Chifflard, P., Hübner, R., and Kleber, A.: Influence of cover beds on slope hydrology, in: Mid-Latitude Slope Deposits (Cover Beds), edited by: Kleber, A. and Terhorst, B., vol. 66 of Developments in Sedimentology, Elsevier, Amsterdam etc., 127–152, 2013. Oldenborger, G. A., Knoll, M. D., Routh, P. S., and LaBrecque, D. J.: Time-lapse ERT monitoring of an injection/withdrawal experiment in a shallow unconfined aquifer, Geophysics, 72, F177–F188, 2007. Perri, M. T., Cassiani, G., Gervasio, I., Deiana, R., and Binley, A.: A saline tracer test monitored via both surface and cross-borehole electrical resistivity tomography: comparison of time-lapse results, J. Appl. Geophys., 79, 6–16, 2012. Popp, S., Altdorff, D., and Dietrich, P.: Assessment of shallow subsurface characterisation with non-invasive geophysical methods at the intermediate hill-slope scale, Hydrol. Earth Syst. Sci., 17, 1297–1307, <a href="http://dx.doi.org/10.5194/hess-17-1297-2013">https://doi.org/10.5194/hess-17-1297-2013</a>, 2013. Ramirez, A., Daily, W., LaBrecque, D. J., Owen, E., and Chesnut, D.: Monitoring an underground steam injection process using electrical resistance tomography, Water Resour. Res., 29, 73–87, 1993. Robinson, D. A., Binley, A., Crook, N., Day-Lewis, F. D., Ferré, T. P. A., Grauch, V. J. S., Knight, R., Knoll, M. D., Lakshmi, V., Miller, R., Nyquist, J., Pellerin, L., Singha, K., and Slater, L.: Advancing process-based watershed hydrological research using near-surface geophysics: a vision for, and review of, electrical and magnetic geophysical methods, Hydrol. Process., 22, 3604–3635, 2008a. Robinson, D. A., Campbell, C. S., Hopmans, J. W., Hornbuckle, B. K., Jones, S. B., Knight, R., Ogden, F., Selker, J., and Wendroth, O.: Soil moisture measurement for ecological and hydrological watershed-scale observatories: a review, Vadose Zone J., 7, 358–389, 2008b. Robinson, D. A., Abdu, H., Lebron, I., and Jones, S. B.: Imaging of hill-slope soil moisture wetting patterns in a semi-arid oak savanna catchment using time-lapse electromagnetic induction, J. Hydrol., 416, 39–49, 2012. Roy, A. and Apparao, A.: Depth of investigation in direct current methods, Geophysics, 36, 943–959, 1971. Rücker, C. and Günther, T.: The simulation of Finite ERT electrodes using the complete electrode model, Geophysics, 76(4), F227–238, 2011. Sauer, D., Scholten, T., and Felix-Henningsen, P.: Verbreitung und Eigenschaften periglaziärer Lagen im östlichen Westerwald in Abhängigkeit von Gestein, Exposition und Relief, Mitt. Dtsch. Bodenkdl. Ges., 96, 551–552, 2001. Scholten, T.: Periglaziäre Lagen in Mittelgebirgslandschaften – Verbreitungssystematik, Eigenschaften und Bedeutung für den Landschaftswasser- und stoffhaushalt, in: Tagungsbeiträge IFZ-Workshop Ressourcensicherung in der Kulturlandschaft, Selbstverlag, Justus-Liebig-Universität, Gießen, 11–15, 1999. Schön, J. H.: Physical Properties of Rocks: Fundamentals and Principles of Petrophysics, vol. 18 of Handbook of Geophysical Exploration: Seismic Exploration, Elsevier, Oxford, 2004. Singha, K. and Gorelick, S. M.: Saline tracer visualized with three-dimensional electrical resistivity tomography: field-scale spatial moment analysis, Water Resour. Res., 41, W05023, <a href="http://dx.doi.org/10.1029/2004WR003460">https://doi.org/10.1029/2004WR003460</a>, 2005. Slater, L., Binley, A., Daily, W., and Johnson, R.: Cross-hole electrical imaging of a controlled saline tracer injection, J. Appl. Geophys., 44, 85–102, 2000. Tilch, N., Uhlenbrook, S., Didszun, J., Wenninger, J., Kirnbauer, R., Zillgens, B., and Leibundgut, C.: Hydrologische Prozessforschung zur Hochwasserentstehung im Löhnersbach-Einzugsgebiet (Kitzbüheler Alpen, Österreich), Hydrol. Wasserbewirts., 50, 67–78, 2006. Tromp-van Meerveld, H. J.: Hillslope hydrology: from patterns to processes, Ph.D. thesis, Oregon State University, Corvallis, 2004. Tromp-van Meerveld, H. J. and McDonnell, J. J.: Assessment of multi-frequency electromagnetic induction for determining soil moisture patterns at the hillslope scale, J. Hydrol., 368, 56–67, 2009. Uchida, T., McDonnell, J. J., and Asano, Y.: Functional intercomparison of hillslopes and small catchments by examining water source, flowpath and mean residence time, J. Hydrol., 327, 627–642, 2006. Uhlenbrook, S.: Von der Abflussbildungsforschung zur prozessorientierten Modellierung – ein Review, Hydrol. Wasserbewirts., 49, 13–24, 2005. Uhlenbrook, S., Didszun, J., and Wenninger, J.: Source areas and mixing of runoff components at the hillslope scale – a multi-technical approach, Hydrolog. Sci. J., 53, 741–753, 2008. Vanderborght, J., Kemna, A., Hardelauf, H., and Vereecken, H.: Potential of electrical resistivity tomography to infer aquifer transport characteristics from tracer studies: a synthetic case study, Water Resour. Res., 41, W06013, <a href="http://dx.doi.org/10.1029/2004WR003774">https://doi.org/10.1029/2004WR003774</a>, 2005. Völkel, J., Leopold, M., Mahr, A., and Raab, T.: Zur Bedeutung kaltzeitlicher Hangsedimente in zentraleuropäischen Mittelgebirgslandschaften und zu Fragen ihrer Terminologie, Petermann. Geogr. Mitt., 146, 50–59, 2002a. Völkel, J., Zepp, H., and Kleber, A.: Periglaziale Deckschichten in Mittelgebirgen – ein offenes Forschungsfeld, Ber. deuts. Landesk., 76, 101–114, 2002b. Wenninger, J., Uhlenbrook, S., Tilch, N., and Leibundgut, C.: Experimental evidence of fast groundwater responses in a hillslope/floodplain area in the Black Forest Mountains, Germany, Hydrol. Process., 18, 3305–3322, 2004. Zhou, B. and Dahlin, T.: Properties and effects of measurement errors on 2-D resistivity imaging surveying, Near Surf. Geophys., 1, 105–117, 2003. Zhou, Q. Y., Shimada, J., and Sato, A.: Three-dimensional spatial and temporal monitoring of soil water content using electrical resistivity tomography, Water Resour. Res., 37, 273–285, 2001.