The scale of interest of many hydrologic processes is much larger than the support volume of our available measurement methods (e.g. tensiometers, time domain reflectometry, neutron probes). The use of small-scale measurements to constrain large-scale models introduces significant uncertainties. It seems that it would be advantageous to use large-scale measurements to constrain our models of large-scale processes. However, this requires improved understanding of the responses of these methods to large-scale processes. We present numerical analyses of the use of gravimeters to constrain models of large-scale processes; specifically, wetting front velocity beneath artificial infiltration facilities and unconfined aquifer responses to pumping for municipal supply. We show that measurement uncertainties limit the processes to which the gravity method should be applied. For those processes that are amenable to monitoring with gravimetry, we show that quantitative use of the measurements requires coupled hydrogeophysical analysis. This step is necessary to avoid the systematic errors that commonly arise due to independent interpretation of indirect methods for hydrologic applications.
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