Advanced type curves for vertical groundwater flow estimation from temperature profiles. Applications to real scenarios

Abstract

Groundwater discharge or recharge in aquifers can be obtained from the analysis of temperature profiles, a costefficient method widely applied in hydrogeology. In this study we proposed a set of type curves that can be used for estimating the vertical velocity flow, and have the potential to allow, in certain cases, the assessment of the thermal diffusivity of the soil matrix. The solutions, represented graphically, establish the dependencies of the basic parameters involved in the process: groundwater velocity, thermal conductivity, specific heat, aquifer depth and harmonic temperature period. Using the non-dimensionalization technique, the mentioned parameters were organized in dimensionless groups which are verified by numerical simulations. For the estimates of the groundwater velocity, transient temperature-depth measurements or steady state amplitudes of the harmonic oscillation were used as input data. In this last case, a particular type curve solution allows us to assess the depth from which temperature oscillations have a negligible amplitude compared to the amplitude at the ground surface. The resulting dependencies have been applied to estimate the groundwater velocity in real aquifers and laboratory experiences.