Document Type : Research Paper

Authors

1 ranian Academic Center for Education, Culture and Research, Kerman branch, Iran

2 Department of Civil Engineering, Shahid Bahonar University, Kerman, Iran

Abstract

Electronic weather stations have increased the availability of weather data for computing hourly and daily reference evapotranspiration (ETo). There is a rational question applied for different climate conditions whether the sum of hourly ETo computation may differ from direct computed daily ETo. In this study for the Kerman area, daily and hourly reference crop water consumption were estimated by the Penman-Monteith equation, using meteorological data collected in one hour intervals by an automatic weather station at Iranian Academic Center for Education, Culture and Research (ACECR), Kerman city, Iran. The direct computed daily evapotranspiration values were compared with the sum of hourly computed evapotranspiration values. Results indicated that there is a distinctive difference between the values as calculated for this experimental station. Based on two tail 95% level t-test, the direct computed daily ETo was greater than the sum of hourly computed ETo. Finally, the relationship of daily and sum of hourly ETo for the study area were presented which can be utilized to compare and convert the computed values.

Keywords

Allen R.G., Jensen M.E., Wright J.L., Burman, R.D., Operational estimates of reference evapotranspiration, Agronomy Journal 81 (1989) 650-662.
Allen R.G., Smith M., Pereira, L.S., Perrier A., An update for the calculation of reference evapotranspiration, ICID Bulletin 43 (1994) 35-92.
Amatya D.M., Skaggs R.W., Gregory J.D., Comparison of methods for estimating REF-ET, Journal of Irrigation and Drainage Engineering 121 (1995) 427–435.
Allen R.G., Pereira, L.S., Raes D., Smith M., Crop evapotranspiration: Guidelines for computing crop water requirements. Irrigation and Drainage, United Nation food and Agriculture Organization, No: 56, Rome, (1988).
Berengena J., Gavila´n P., Reference evapotranspiration estimation in a highly advective semiarid environment, Journal of Irrigation and Drainage Engineering 131 (2005) 147–163.
Doorenbos J., Pruitt W.O., Guideline for predicting crop water requirements, FAO Irrigation and Drainage, No: 24, Rome, Italy, 193, (1977).
Gavila´n P., Berengena J., Allen, R. G. Measuring versus estimating net radiation and soil heat flux: Impact on Penman–Monteith reference ET estimates in semiarid regions, Agricultural Water Management 89 (2007) 275-286.
Howell T.A., Evett S.R., Schneider A.D., Dusek D.A., Copeland K.S., Irrigated fescue grass ET compared with calculated reference grass ET, In: Proceedings of the 4th National Irrigation Symposium. ASAE. Phoenix, (2000)
Irmak S., Irmak A., Jones, J.W., Howell, T.A., Jacobs, J.M., Allen, R. G., Hoogenboom G., Predicting daily net radiation using minimum climatological data, Journal of Irrigation and Drainage Engineering 129 (2003) 256–269.
Itenfisu D., Elliott R.L., Allen R.G., Walter I.A., Comparison of reference evapotranspiration calculations as part of the ASCE standardization effect, 129 (2003) 440-448.
Jacobs J.M., Evaluation of reference evapotranspiration methodologies and AFSIRS crop water use simulation model, University of Florida, Gainesville, Florida, (2001)
Jensen M.E., Burman R.D., Allen R.G., evapotranspiration and irrigation water requirements., ASCE Manuals and Reports on Engineering Practice, No. 70. ASCE. New York, (1990).
Kermani E.F., Barani G.A., Khanjani M.J., Developing a framework for compatibility analysis of predictive climatic variables distribution with reference evapotranspiration in probabilistic analysis of water requirement, Journal of Applied Research in Water and Wastewater 1 (2014) 68-74.
Katul G.G., Cuenca R.H., Grebet P., Wright J.L., Pruitt, W.O., Analysis of evaporative flux data for various climates, J Journal of Irrigation and Drainage Engineering 118 (1992) 601–618.
Liverman D., Verstraete M.M., Fischer G., Earth and environmental science, Book reviews, Journal of Climate change 6 (1984).
Lo´pez-Urrea R., Martı´n de Santa Olalla F., Fabeiro C., Moratalla A., An evaluation of two hourly reference evapotranspiration equations for semiarid conditions, Agriculture Water Management 86 (2006) 277-282.
Neter J., Kunter M.H., Nachtsheim C.J., Wasserman W., Applied Linear Statistical Models, IRWIn, USA, p. 1470, (1996).
Ortega-Farias S., Antonioletti R., Olioso A., Net radiation model evaluation at an hourly time step for Mediterranean conditions, Agronomy 20 (2000) 157–164.
Sharma M.L., Estimating Evapotranspiration, Advances in Irrigation 3 (1985) 213–281.
Smith M., Allen, R.G., Pereira L.S., Revised FAO methodology for crop water requirements. Evapotranspiration and irrigation scheduling. In: Proceedings of the International Conference, San Antonio. ASAE, pp. 116–123 (1996)
Snyder R.L., Pruitt W.O., Evapotranspiration data management in California. ASCE water forum, Vol. 92: Baltimore, Md, (1992).
Temesgen B., Eching S.B., Frame K., Comparison of some reference evapotranspiration equation for California, Journal of Irrigation and Drainage 131 (2005) 73-84.
Ventura F.D., Spano Duce P., Snyder R.L., An evaluation of common evapotranspiration equation, Irrigation Science 18 (1999) 163-170.
Villa Nova N.A., Pereira A.B., Shock C.C., Estimation of Reference Evapotranspiration by an Energy Balance Approach, Biosystems Engineering 96 (2007) 605-615.
Wright J.L., Allen R.G., Howell T.A., Conversion between evapotranspiration reference and methods. In: Proceedings of 4th National Irrigation Symp., American Society of Agricultural Engineers, St. Joseph, Mich., (2000) 251-259.