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Evapotranspiration (ET) is a critical, but difficult to estimate, part of the global water cycle. A variety of methods exist to measure ET, but each have their own advantages and drawbacks. In this work we focus on the potential for using diurnal water level variation to estimate ET, and propose a novel sensor to measure fine scale (sub millimeter) water table variation using a laser-based sensor. The sensor consists of a phase-shift based laser rangefinder controlled by a Raspberry Pi microcomputer, and is designed to work in a remote environment with the potential ability to be deployed for several months at a time. This approach has the potential to eliminate measurement error associated with pressure and temperature sensitivity apparent in most commonly used pressure transducers, expanding our ability to estimate this important hydrologic flux. Preliminary results indicate a high level of accuracy in comparison to a pressure based transducer, but without noise and errors associated with changing temperatures and barometric pressure. Future tests will determine the sensor’s ability to be deployed in a remote environment, and will see how it fares in a complex natural system in comparison with current technologies. |