DOI: 10.5194/hess-22-1509-2018
Scopus记录号: 2-s2.0-85042703619
论文题名: Calibrating electromagnetic induction conductivities with time-domain reflectometry measurements
作者: Dragonetti G ; , Comegna A ; , Ajeel A ; , Piero Deidda G ; , Lamaddalena N ; , Rodriguez G ; , Vignoli G ; , Coppola A
刊名: Hydrology and Earth System Sciences
ISSN: 10275606
出版年: 2018
卷: 22, 期: 2 起始页码: 1509
结束页码: 1523
语种: 英语
Scopus关键词: Calibration
; Electric conductivity
; Electromagnetic induction
; Linear transformations
; Mathematical transformations
; Newton-Raphson method
; Permittivity measurement
; Reflection
; Reflectometers
; Singular value decomposition
; Soils
; Spatial distribution
; Time domain analysis
; Apparent electrical conductivity
; Electrical conductivity
; Electromagnetic induction sensors
; Gauss-Newton methods
; Generalized singular value decomposition
; Inversion techniques
; Regularization strategies
; Time domain reflectometry
; Soil surveys
; calibration
; data set
; electrical conductivity
; electromagnetic method
; measurement method
; methodology
; numerical method
; rhizosphere
; singular value decomposition
; spatial distribution
; time domain reflectometry
英文摘要: This paper deals with the issue of monitoring the spatial distribution of bulk electrical conductivity, σb, in the soil root zone by using electromagnetic induction (EMI) sensors under different water and salinity conditions. To deduce the actual distribution of depth-specific σb from EMI apparent electrical conductivity (ECa) measurements, we inverted the data by using a regularized 1-D inversion procedure designed to manage nonlinear multiple EMI-depth responses. The inversion technique is based on the coupling of the damped Gauss-Newton method with truncated generalized singular value decomposition (TGSVD). The ill-posedness of the EMI data inversion is addressed by using a sharp stabilizer term in the objective function. This specific stabilizer promotes the reconstruction of blocky targets, thereby contributing to enhance the spatial resolution of the EMI results in the presence of sharp boundaries (otherwise smeared out after the application of more standard Occam-like regularization strategies searching for smooth solutions). Time-domain reflectometry (TDR) data are used as ground-truth data for calibration of the inversion results. An experimental field was divided into four transects 30g m long and 2.8g m wide, cultivated with green bean, and irrigated with water at two different salinity levels and using two different irrigation volumes. Clearly, this induces different salinity and water contents within the soil profiles. For each transect, 26 regularly spaced monitoring soundings (1g m apart) were selected for the collection of (i) Geonics EM-38 and (ii) Tektronix reflectometer data. Despite the original discrepancies in the EMI and TDR data, we found a significant correlation of the means and standard deviations of the two data series; in particular, after a low-pass spatial filtering of the TDR data. Based on these findings, this paper introduces a novel methodology to calibrate EMI-based electrical conductivities via TDR direct measurements. This calibration strategy consists of a linear mapping of the original inversion results into a new conductivity spatial distribution with the coefficients of the transformation uniquely based on the statistics of the two original measurement datasets (EMI and TDR conductivities). © Author(s) 2018. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/79373
Appears in Collections: 气候变化事实与影响
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作者单位: Mediterranean Agronomic Institute (MAIB) - Land and Water Department, Valenzano (Bari), Italy; University of Basilicata, School of Agricultural, Forestry and Environmental Sciences - Hydraulics and Hydrology Division, Potenza, Italy; Dipartimento di Ingegneria Civile, Ambientale e Architettura, Università di Cagliari, Cagliari, Italy; Dipartimento di Matematica e Informatica, Università di Cagliari, Cagliari, Italy; Groundwater and Quaternary Geology Mapping Department, Geological Survey of Denmark and Greenland, Aarhus, Denmark
Recommended Citation:
Dragonetti G,, Comegna A,, Ajeel A,et al. Calibrating electromagnetic induction conductivities with time-domain reflectometry measurements[J]. Hydrology and Earth System Sciences,2018-01-01,22(2)