Getting the Most from Temperature Measurements in Groundwater-Surface Water Interaction Studies

Temperature measurements have become popular in groundwater-surface water interaction studies in recent years. Instrumentation has become relatively inexpensive and emerging technologies, such as distributed temperature sensors and infrared imaging have made data easy to obtain. However, analysis of temperature data has often relied on several simplifying assumptions in solving the relevant differential equations. These assumptions frequently include heat and fluid flow in one dimension only and steady state conditions. While these simplifications have streamlined the process of estimating Darcy fluxes, recent studies showing significant spatial and transient variability in temperature emphasize the need to reexamine these assumptions. Numerical simulations utilizing stochastic hydraulic conductivity distributions suggest that the resulting errors could be significant and heterogeneity is likely underestimated. Acknowledgement of these heterogeneities in combination with more complex models should allow for temperature measurements to better inform our understanding of groundwater-surface water interaction.