Predicting Temperature and Heat Flow in a Sandy Soil by Electrical Modeling

Abstract

A model based on an electrical analogy between a soil column and an electrical transmission line was developed to predict temperature and heat flow as functions of depth and time in a sandy soil, taking into account changes in soil thermal conductivity and volumetric heat capacity due to variations in water content. The model was excited alternatively by both measured soil temperature at the 1‐cm depth and solar radiation [Sr(t)], and solved with available electrical analysis software. The results were compared with field data collected during a 35‐d field experiment carried out in the Lido beach, Venice, Italy. A very simple transfer function was identified for using measured Sr(t) as the input signal. This transfer function turned out to vary inversely with Sr(t). When the model is excited by temperature, and soil water content corrected every 5 d, the root mean square error (RMSE) for the calculated temperature at the 5‐cm depth is less than 1°C. When it is excited by Sr(t), the RMSE at the 1‐cm depth is less than 2°C. Hourly temperatures at different depths were found to depend strongly on surface phenomena, and to a lesser extent on other factors like soil water content below the top layers.

Estimating the soil temperature profile from a single depth observation: A simple empirical heatflow solution

“…Many models have been developed to extend limited temperature data [ Van Wijk and De Vries , 1963; Camillo , 1989; Cuaraglia et al , 2001; Elias et al , 2004]. When properly implemented, these models can be used to extrapolate soil profile temperatures with reasonable accuracy from a single subsurface measurement.…”

“…This addition makes the model better suited for inter‐seasonal timescales. A different approach was used by Cuaraglia et al [2001], who used electrical modeling to predict temperature and heat flow at one depth from solar radiation.…”

Artificial Nesting Hills Promote Wild Bees in Agricultural Landscapes

“…At two sampling events, the soil temperature at a 5 cm depth reached particularly high temperature maxima of 40 °C, but the highest temperature measured at a 15 cm depth was about 5 °C lower than that at 5 cm depth. As the brood area of most ground-nesting bees is estimated to be deeper than 10 cm [ 13 , 22 , 51 ], temperature peaks caused by a hot air temperature and solar radiation are less pronounced [ 52 , 53 ]. Temperatures around 45 °C are predicted to cause serious stress [ 22 ].…”

Reconstruction of soil thermal field from a single depth measurement

“…On the other hand, numerous analytically-based approaches have been developed in past decades, to predict soil temperature and/or soil heat flux based on the one-dimensional (1D) heat diffusion, with applications to a wide range of areas including agronomy, meteorology, hydrology and ecology (Gao et al, 2003;Guaraglia et al, 2001;Holmes et al, 2008;Horton and Wierenga, 1983;Nunez et al, 2010). These models made use of analytical solutions of heat conduction in semi-infinite soils, and are numerically more economic and provide deeper insight into the subsurface physics as compared to FEM.…”

“…represented by sinusoidal forms or by Fourier series (Gao et al, 2003;Holmes et al, 2008;Horton and Wierenga, 1983;Nunez et al, 2010) whereas general boundary conditions representing more realistic natural forcing are not permissible. (3) Auxiliary profile measurement of soil temperature, heat flux, and/or soil water content at different depths is required to construct the complete thermal field (Guaraglia et al, 2001;Kimball and Jackson, 1975;Liebethal et al, 2005), whereas only partial information of the thermal field can be reconstructed using measurements at a single depth (Wang and Bras, 1999).…”