Direct Load Cell-Based Weighing Lysimeter Systemby Richard G. Allen, Utah State Univ, Logan, United States,
D. Ken Fisher, Utah State Univ, Logan, United States,
Abstract: A low-cost weighing lysimeter system is described which is capable of measuring evapotranspiration with an accuracy of 0.05-0.10 mm. A two-lysimeter system with electronic data logger can be installed for a cost of $15,000 for 1 m2 surface dimensions and $25,000 for 2 m2 surface dimensions. With underground placement of cantilevered load cells, the 1 m2 system can measure evapotranspiration for periods as short as 30 minutes. The lysimeter tank and load cell mounting is described and necessary datalogger operation and programming to obtain high accuracy is discussed. Problems with electronic system noise and drifting of zero-points of load cells due to thermal changes are described. Comparison of lysimeter measurements at Logan, Utah with aerodynamic energy balance, and Penman-Monteith methods are made.
Subject Headings: Measuring instruments | Load factors | Evapotranspiration | Load tests | Water resources | Benefit cost ratios | Computer programming | Cantilevers | Utah | North America | United States
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