Title: Calibration of pan coefficient for a semi-arid area: a case study

Authors: Sayed-Hamed Sajjadi; Mohsen Zarghani; Atefe Dolat-Abadi; Elham Nazari; Hamed Sarkardeh

Addresses: Department of Civil Engineering, Faculty of Engineering, Hakim-Sabzevari University, Sabzevar, Iran ' Department of Civil Engineering, Faculty of Engineering, Hakim-Sabzevari University, Sabzevar, Iran ' Department of Civil Engineering, Faculty of Engineering, Hakim-Sabzevari University, Sabzevar, Iran ' Department of Civil Engineering, Faculty of Engineering, Hakim-Sabzevari University, Sabzevar, Iran ' Department of Civil Engineering, Faculty of Engineering, Hakim-Sabzevari University, Sabzevar, Iran

Abstract: Accuracy of estimated evaporation in the arid and semi-arid areas for hydrologic works is a challenging problem and needs to be calibrated for certain areas. The current study has focused on estimating the accuracy and calibrating of evaporation, evapo-transpiration and pan coefficient equations. In this research, pan evaporation data of Sabzevar synoptic station in Khorasan-Razavi province, Iran was used for investigating the accuracy of Penman (1948) and Shuttleworth (1993) equations for evaporation of pan. Moreover, a comprehensive comparison was performed on actual pan coefficient and also other researcher equations. Finally, three equations were performed for pan evaporation, reference evapo-transpiration and pan coefficient. Calculated determination coefficients are 0.95, 0.87 and 0.64 for evapo-transpiration, pan evaporation and daily pan coefficient, respectively and for 10-day and monthly pan coefficient, this value increased to 0.811 and 0.863, respectively. The RMSE and P-Values showed that presented equations are acceptable.

Keywords: evaporation; pan coefficient; empirical equations; semi-arid area; Sabzevar.

DOI: 10.1504/IJHST.2017.086948

International Journal of Hydrology Science and Technology, 2017 Vol.7 No.3, pp.256 - 267

Received: 24 Dec 2015
Accepted: 28 Jun 2016

Published online: 26 Sep 2017 *

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