Evaluation of efficiency of long-term weather data in trickle and sprinkler irrigation management

Subject Areas : Farm water management with the aim of improving irrigation management indicators

Samia Amiri ¹ ( B.Sc. Graduate, Water Engineering Department, College of Agriculture, Isfahan University of Technology, Isfahan, Iran )
Mahdi Gheysari ² ( Assistant Professor, Water Engineering Department, College of Agriculture, Isfahan University of Technology, Isfahan, Iran )
Bita Movavejalahkami ³ ( PhD of irrigation and drainage, Isfahan University of Technology, Head of researching of Hidrab Andish Consulting Engineering Company, Isfahan, Iran )

Received: 2012-04-21 Accepted : 2012-09-06 Published : 2012-12-10

Keywords: automatic weather station, crop water requirement, Evapotranspiration, smart irrigation,

Abstract :

Proper estimation of crop water requirement is very important for water resource conservation in Iran. However, in most studies in Iran, the estimation of evapotranspiration is based on long-term weather data. However, use of simultaneous weather data of a non-agricultural weather station may underestimate or overestimate the crop water requirement. Therefore, it is essential for irrigation specialist to be aware of the error of evapotranspiration calculated by long-term weather data. The objective of this study was to evaluate accuracy of evapotranspiration of reference crop using long-term weather data in comparison with simultaneous weather data in drip and sprinkler irrigation. The period was designated to be from 1995 to 2009 in Isfahan weather station, Kabootarabad weather station and Shahid Beheshti airport weather station. The maximum value of n-RMSE using long-term weather data in comparison to simultaneous weather data were 24% for trickle irrigation and 18% for sprinkler irrigation management, 22% in spring, 20% in summer, 44% in fall and 56% in winter. According to results of this study, the application of long-term weather data in deficit irrigation management is not recommended. On the other hand, due to sensitivity of trickle irrigation to water stress, the application of long-term weather data for estimating of evapotranspiration in irrigation scheduling is not recommended. Finally, application of automatic weather stations and simultaneous weather data for accurate irrigation management particularly in deficitirrigation management in critical situation of water shortage is recommended.