See more from this Session: Measurement and Modeling of near-Surface Soil Water and Energy Fluxes: I
Wednesday, October 19, 2011: 10:40 AM
Henry Gonzalez Convention Center, Room 007B, River Level
Evapotranspiration (ET) is a main component of the hydrology cycle. It consists of soil water evaporation (E) and plant transpiration (T). Accurate partitioning of ET into E and T is challenging. We measured soil water E using heat pulse sensors and a micro-Bowen ratio system, T using stem flow gauges, and ET using an eddy covariance system in a corn (Zea mays L.) field. Potential ET was also calculated with the Priestley-Taylor equation. The dynamic soil water E estimates from heat pulse sensors agreed well with those from the micro-Bowen ratio system, and the differences of the daily soil water E estimates from heat pulse and micro-Bowen ratio methods were within 0.3 mm. ET estimates from the sum of measured heat pulse E and stem flow T, from eddy covariance measurements, and from Priestley-Taylor calculations had similar trends. During the measurement period, measured E+T and eddy covariance ET accounted for 84% and 61% of potential ET, respectively. E and T accounted for 8% and 92%, respectively, of the sum of the measured E+T. The heat pulse method and the micro-Bowen ratio method are promising ways to measure soil water E, and they are useful for partitioning ET into E and T in a cropped field.