Heat transfer Effect by soil temperature changes under shallow groundwater in the Mu Us desert, Northern China

Abstract:

Soil temperature change is principle elements to biological growth, soil freeze or thawing process. A situ field was conducted in the Mu Us desert of Wushen Qi County, Inner Mongolia, to mainly monitor soil temperature, moisture content and groundwater level. The unconfined aquifer constituted by Quaternary fine eolian sand, groundwater level is 125cm. This paper, choosing date from May 1, 2013 to April 30, 2014, soil day temperature is conducted by 3:00, 6:00,till 24:00, vertical spacing including 2cm,5 cm、10 cm、15 cm、20 cm, 75cm,125cm,which its symbol is T_10, T_15, T_20, T₇₅, T₁₂₅ respectively. Here, surface layer temperature T_S calculated by soil temperature of 2-5cm depth. Due to only 5 minutes interval, this state was taken as a state one. (1) soil temperature has mixture change on surface layer and its temperature different is over 35 ℃. (2) Surface layer temperature changes of every month have three stages and its conducted heat, which calculated between T_S and T₁₀. Since T_S exceeds T₁₀ and heat transfer direction is from surface to underground in May, June and July 2013, even heat transfer amounts reduced by participation in July. However, T_S is inferior to T₁₀ and conduced heat direction reverse in August till to February 2014.Continually conduced heat start to next circulation and then it’s heat direction from surface to underground due to T_S exceeds T₁₀ again in March and April 2014. (3) Temperature changes of phreatic water table every month have also three stages and its conducted heat which calculated between T₇₅ and T₁₂₅, heat transfer direction from unsaturated zone to saturated zone due to T₇₅ exceeds T₁₂₅ from May till middle September 2013. However, T₇₅ is inferior to T₁₂₅ and heat direction reverse from late September 2013 till May 2014, but conduced heat direction starts to change from unsaturated zone to saturated zone again in early April 2014.The result can imply shallow gruondwater has some contribution to surface layer temperature in different seasons.