Journal
JOURNAL OF IRRIGATION AND DRAINAGE ENGINEERING
Volume 143, Issue 4, Pages -Publisher
ASCE-AMER SOC CIVIL ENGINEERS
DOI: 10.1061/(ASCE)IR.1943-4774.0001154
Keywords
Reference evapotranspiration; FAO-56 Penman-Monteith; Limited data; Valiantzas equations; Eastern Africa
Ask authors/readers for more resources
The objective of this study was to evaluate the FAO-56 Penman-Monteith (FAO-PM) reference evapotranspiration (ETo) equation and two Valiantzas equations for estimating daily reference evapotranspiration under limited data and four other ETo equations across Tanzania and the southwestern Kenya. The results showed the applicability of the FAO-PM equation under missing solar radiation (Rs), relative humidity (RH), and wind speed (u2) data with regression slopes varying from 0.68 to 0.89, from 0.79 to 1.00, and from 0.79 to 0.96, respectively, and root mean squared error (RMSE) lower than 0.63, 0.53, and 0.44mm/day under the respective conditions. Under lacking relative humidity data, the simplified method provided very good ETo estimates. There were large discrepancies in ETo estimates with the FAO-PM equation when two or three weather variables were missing. The Valiantzas 2 equation with full data provided the most accurate ETo estimates under the eastern Africa conditions with coefficient of determination R-2 > 0.97, regression slope ranging from 0.96 to 1.05, RMSE < 0.23mm/day, MBE ranging from -0.03 to 0.17mm/day, and very low relative error (RE < 5.5%). The Irmak, Abtew, Hansen, and Hargreaves equations produced moderately accurate ETo estimates with RMSE as high as 0.91, 0.74, 0.74, and 0.66mm/day for the respective equations, and relative error as high as 16.3%.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available