Vol. 110 No. 1 (2016)
Research Papers

Estimation of Turc reference evapotranspiration with limited data against the Penman-Monteith Formula in Senegal

Ousmane Coly Diouf
Geology Department, Cheikh Anta Diop University of Dakar
Bio
Lutz Weihermüller
Forschungszentrum Jülich GmbH, Agrosphere Institute IBG-3, Jülich,
Bio
Kader Ba
Geology department, Cheikh Anta Diop University of Dakar
Bio
Seynabou Cisse Faye
Geology department, Cheikh Anta Diop University of Dakar
Bio
Serigne Faye
Geology department, Cheikh Anta Diop University of Dakar
Bio
Harry Vereecken
Forschungszentrum Jülich GmbH, Agrosphere Institute IBG-3, Jülich
Bio
Published June 27, 2016
How to Cite
Diouf, O. C., Weihermüller, L., Ba, K., Cisse Faye, S., Faye, S., & Vereecken, H. (2016). Estimation of Turc reference evapotranspiration with limited data against the Penman-Monteith Formula in Senegal. Journal of Agriculture and Environment for International Development (JAEID), 110(1), 117-137. https://doi.org/10.12895/jaeid.20161.417

Abstract

Estimation of daily evapotranspiration (ET0) is required for efficient irrigation management in Senegal but physically based equations such as the Penman–Monteith (PM) approach need large inputs number which are not always available. Therefore empirical approaches such as Turcs formula are often used. Unfortunately, Turc’s formula showed high annual ET0 compared to FAO Penman–Monteith (FAO-PM) ET0 for stations in this region. Moreover, Turc underestimates mean daily ET0 for the dry season and overestimates ET0 for the wet season. For reevaluation, Turc’s empirical parameters (a and b) were fitted to match FAO-PM ET0, whereby the fitting did not improve the prediction substantially and only assuming C being independent on relative humidity yielded better agreement. In a second step universal a and b parameters were estimated for different stations in Senegal. The results indicate that one set of parameters (a and b) can be used to predict all station ET0 with fairly high accuracy indicate by a R2 of 0.80 and an RMSE of 0.71 mm day-1. Based on these findings we propose to use Turc’s approach in Senegal only with the parameters a = 0.16 and b = 29.19 with the constrain that C is independent on relative humidity.