Abstract
We observed shallow groundwater levels with temperatures and discussed their seasonal fluctuations under a series of agricultural land uses along a gentle sloping topography in northeast Thailand. When the study sites were characterized into such three categories on the basis of their land uses and topographies as A: lower (paddy fields), B: middle (paddy fields) and C: upper (upland), we recognized that the shallow groundwater temperatures tend to be in the order of A<B<C. As one of the main possibilities to explain this groundwater temperature regime, we suggested that the latent heat loss by evapotranspiration would remain larger in the lower sites than in the upper sites due to the hydrologic location of the lower sites which is subjected to higher soil water content.
