TY - JOUR ID - 81008 TI - Evaluation of Pan Coefficient Estimation Methods to Calculate the Amount of Evapotranspiration (Case Study of Kurdistan Province) JO - Iranian Journal of Soil and Water Research JA - IJSWR LA - en SN - 2008-479X AU - zare- abyaneh, hamid AU - esmaeili, soror AD - Department Water Sciences and Engineering, Faculty of Agriculture, Bu-Ali Sina University, Hamedan, Iran. AD - Department Water Sciences and Engineering,, Faculty of Agriculture, Bu-Ali Sina University, Hamedan, Iran. Y1 - 2021 PY - 2021 VL - 52 IS - 2 SP - 329 EP - 344 KW - Reference Plant Evapotranspiration KW - Pan coefficient KW - FAO Penman Monteith KW - Kurdistan province DO - 10.22059/ijswr.2021.311175.668761 N2 - Plant water requirement or evapotranspiration (ET) is one of the main components of water balance and a key factor in irrigation planning to improve water use efficiency of agricultural lands. Different methods have been proposed to determine evapotranspiration directly using lysimeter and indirectly using computational methods. Evaporation pan is one of the indirect, simple and suitable methods for estimating the evapotranspiration of the reference plant and the main plant, which shows the combined effects of atmospheric parameters such as air temperature, air humidity, radiation and wind. In this study, using 20-year meteorological data (1999-2018) of the all synoptic stations in Kurdistan province, the value of pan coefficient was estimated using the methods: Cuenca (1989), Raghuwanshi & wallender (1998), Modified Snyder, Mohamed et al (2008), Allen and Pruitt (1991), Snyder (1992), Orang (1998), Pereira (1995), Christiansen (1990) and FAO-24 (1997). In order to evaluate the accuracy of estimating evapotranspiration obtained from pan evaporation mehod, the FAO Penman-Mantith 56 method was used. To evaluate the accuracy of the models and to select the best one, four indicators; (RMSE), (MAE), (MBE) and t-test were used. The final results showed that on a daily, monthly and seasonal basis, the methods of FAO-24 (1997) and Christiansen (1990) had the best performance and the methods of Raghuwanshi & Wallender (1998) and Allen and Perot (1991) had the worst performance. UR - https://ijswr.ut.ac.ir/article_81008.html L1 - https://ijswr.ut.ac.ir/article_81008_06e2837a40e7c30d844bb7d8aba3251d.pdf ER -