Modeling Soil Temperature Variations

Abstract

This paper reports on modeling soil temperature variations. Transient heat flow principles were used in the study, with the assumptions that the heat flow was one-dimensional, the soil was homogenous and that the thermal diffusivity was constant. Average conditions are also assumed. The annual and diurnal (daily) soil temperature cycles were modeled with fairly good accuracy. Differences in measured and predicted soil temperatures were determined at the annual level at depths 0cm (surface), 5cm, 10cm, 20cm, 30cm, 50cm and 100cm while the differences were determined at the diurnal level at depths 5cm, 20cm and 30cm at 9a.m and 3p.m. For the annual cycle; the lowest average absolute error (1.230C) was obtained at the soil surface, with the highest average error (3.520C) obtained at the 10cm soil depth. For the diurnal cycle; the average error was 1.070C at 9am while it was 3.670C at 3p.m. The damping depths for the study area (Ilorin) were 224cm, 12cm and 2cm for the annual, diurnal and hourly cycles, respectively..

JARD Vol. 2 2003: pp. 100-109