Modelling near subsurface temperature with mixed type boundary condition for transient air temperature and vertical groundwater flow

• Published in: Journal of Earth System Science Vol. 121; no. 5; pp. 1177 - 1184
• Main Authors: KUMAR, RAJEEV RANJAN, RAMANA, D V, SINGH, R N
• Format: Journal Article
• Language: English
• Published: India Springer-Verlag 01.10.2012; Springer; Springer Nature B.V
• Subjects: Advection; Air temperature; Analytical models; Boreholes; Boundary conditions; Climate change; Climate models; Coefficients; Conduction heating; Conductive heat transfer; Depth; Depth profiling; Dirichlet problem; Earth and Environmental Science; Earth science; Earth Sciences; Earth, ocean, space; Exact sciences and technology; Geothermal data; Groundwater; Groundwater flow; Heat conduction; Heat flux; Meteorological conditions; Soil; Soil surface temperatures; Soil surfaces; Soil temperature; Soils; Space Exploration and Astronautics; Space Sciences (including Extraterrestrial Physics; Subsurface temperatures; Surface temperature; Surface-air temperature relationships; Temperature distribution; Temperature effects; Thermal analysis; Thermal models; Thermals models; Borehole temperature; climate; groundwater recharge rate; mixed type boundary condition; transient air temperature; advection; models; ground water; air; subsurface; boreholes; depth; aquifers; interpretation; surface temperature; soils; boundary conditions; flow; climate change
• ISSN: 0253-4126; 2347-4327; 0973-774X
• DOI: 10.1007/s12040-012-0220-8

Near-subsurface temperatures have signatures of climate change. Thermal models of subsurface have been constructed by prescribing time dependent Dirichlet type boundary condition wherein the temperature at the soil surface is prescribed and depth distribution of temperature is obtained. In this formulation it is not possible to include the relationship between air temperatures and the temperature of soil surface. However, if one uses a Robin type boundary condition, a transfer coefficient relates the air and soil surface temperatures which helps to determine both the temperature at the surface and at depth given near surface air temperatures. This coefficient is a function of meteorological conditions and is readily available. We have developed such a thermal model of near subsurface region which includes both heat conduction and advection due to groundwater flows and have presented numerical results for changes in the temperature–depth profiles for different values of transfer coefficient and groundwater flux. There are significant changes in temperature and depth profiles due to changes in the transfer coefficient and groundwater flux. The analytical model will find applications in the interpretation of the borehole geothermal data to extract both climate and groundwater flow signals.