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Main Title: Estimating Pore Water Electrical Conductivity of Sandy Soil from Time Domain Reflectometry Records Using a Time-Varying Dynamic Linear Model
Author(s): Aljoumani, Basem
Sanchez-Espigares, Jose A.
Wessolek, Gerd
Type: Article
Language Code: en
Abstract: Despite the importance of computing soil pore water electrical conductivity (σp) from soil bulk electrical conductivity (σb) in ecological and hydrological applications, a good method of doing so remains elusive. The Hilhorst concept offers a theoretical model describing a linear relationship between σb, and relative dielectric permittivity (εb) in moist soil. The reciprocal of pore water electrical conductivity (1/σp) appears as a slope of the Hilhorst model and the ordinary least squares (OLS) of this linear relationship yields a single estimate ( 1/σpˆ ) of the regression parameter vector (σp) for the entire data. This study was carried out on a sandy soil under laboratory conditions. We used a time-varying dynamic linear model (DLM) and the Kalman filter (Kf) to estimate the evolution of σp over time. A time series of the relative dielectric permittivity (εb) and σb of the soil were measured using time domain reflectometry (TDR) at different depths in a soil column to transform the deterministic Hilhorst model into a stochastic model and evaluate the linear relationship between εb and σb in order to capture deterministic changes to (1/σp). Applying the Hilhorst model, strong positive autocorrelations between the residuals could be found. By using and modifying them to DLM, the observed and modeled data of εb obtain a much better match and the estimated evolution of σp converged to its true value. Moreover, the offset of this linear relation varies for each soil depth.
Issue Date: 13-Dec-2018
Date Available: 18-Feb-2019
DDC Class: 620 Ingenieurwissenschaften und zugeordnete Tätigkeiten
Subject(s): electrical conductivity
relative dielectric permittivity
time domain reflectometry
kalman filter
dynamic linear model
Sponsor/Funder: DFG, 325093850, Open Access Publizieren 2017 - 2018 / Technische Universität Berlin
DFG, GRK 2032, Grenzzonen in urbanen Wassersystemen
Journal Title: Sensors
Publisher: MDPI
Publisher Place: Basel
Volume: 18
Issue: 12
Article Number: 4403
Publisher DOI: 10.3390/s18124403
EISSN: 1424-8220
Appears in Collections:FG Ökohydrologie & Landschaftsbewertung » Publications

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