WIT Press

Kerman Weighing Electronic Lysimeter Error Analysis


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B. Bakhtiari, R. Kamyab Moghadas, M. J. Khanjani & H. Taraz


Lysimeter is an important instrument to measure evapotranspiration in the field of irrigation management. The error analysis and calibration of the system is very critical for quality control of collected data. The error sources are many and different. The Kerman weighing electronic lysimeter is a complex of two cultivation tanks, load cells, data logger, and data processing weighing system with 48 m2 under ground building. In this study, ten-minute interval measured evapotranspiration data were analyzed. The Fourier’s series were used to model discrete measured time depended evapotranspiration data. By differentiation of the fitted model the quantity of selected time interval evapotranspiration was computed. By comparing the measured and estimated data the time depended errors were calculated. Computed errors were analyzed, and the statistical distributions of the errors were discussed. Keywords: evapotranspiration, ET, weighing lysimeter, error analysis, Kerman. 1 Introduction Crop evapotranspiration (ET) is a major component of any local hydrologic system. It is an important factor in planning and developing water resources. It should be estimated as correctly as close to avoid any consequence of over or under estimating in local water resources planning. Lysimeter is an instrument to measure actual crop evapotranspiration in field of agricultural irrigation management. It has been used in the United States since the 1930s mainly to measure evapotranspiration (Malone et al. [1]). An excellent summary of


evapotranspiration, ET, weighing lysimeter, error analysis, Kerman.