Skip to main content

Science – Society – Technology

Table 11 Detailed nomenclature for geothermal and soil-related variables

From: A machine learning approach for mapping the very shallow theoretical geothermal potential

Symbol

Unit

Description

\(\alpha\)

(\(\text {m}^{2}\,\text {s}^{-1}\))

Thermal diffusivity

\(\gamma _{d}\)

(g/\(\text {cm}^{3}\))

Dry (bulk) density

\(\gamma _{s}\)

(g/\(\text {cm}^{3}\))

Particle density

\(\gamma _{w}\)

(g/\(\text {cm}^{3}\))

Water density

\(\lambda\)

(\(\text {W K}^{-1}\,\text {m}^{-1}\))

Thermal conductivity

\(\rho\)

(\(\Omega\) m)

Electrical resistivity

\(\omega\)

(\(\text {s}^{-1}\))

Angular frequency of one period in Fourier series

\(a_{n}\)

(–)

First Fourier coefficient for the nth harmonics

\(b_{n}\)

(–)

Second Fourier coefficient for the nth harmonics

\(c_{v}\)

(\(\text {J m}^{-3}\,\text {K}^{-1}\))

Volumetric heat capacity

D

(m)

Damping depth

e

(–)

Void ratio

F

(%)

Percentage sum of sand and gravel fractions in the soil

\(h_{i}\)

(m)

Width of soil strata i

\(I_{1},...,I_{10}\)

(–)

Possible fraction intervals for soil texture variables

\(M_{s}\)

(g)

Mass of solid soil in ground

\(M_{w}\)

(g)

Mass of water in ground

n

(–)

Harmonics index in Fourier series

\(n_{p}\)

(–)

Porosity

\(R_{n}\)

(–)

Amplitude of nth harmonic of Fourier series solution for T

Sd, St, Cl

(%)

Sand, silt, and clay fraction percentage in soil

\(S_{r}\)

(%)

Saturation degree

t

(s)

Time

T

(\(^{\circ }\)C)

Shallow ground temperature

\(T_{0}\)

(\(^{\circ }\)C)

Average ground surface temperature over a year

\(V_{a}\)

(\(\text {m}^{3}\))

Volume of air in ground

\(V_{s}\)

(\(\text {m}^{3}\))

Volume of solid soil in ground

\(V_{T}\)

(\(\text {m}^{3}\))

Total volume of ground

\(V_{v}\)

(\(\text {m}^{3}\))

Volume of void in ground

\(V_{w}\)

(\(\text {m}^{3}\))

Volume of water in ground

w

(%)

Gravimetric water content

z

(m)

Ground depth

  1. (−) signifies no unit