Estimation of Reference Evapotranspiration Using Multiple Linear Regression Models

Abstract

The aim of this study is to estimate the amount of reference evapotranspiration (ETo) by multiple linear regression models (MLRM) developed by using various combinations of air temperature (T, Tmax, Tmin) and relative humidity (RH). For this purpose, using Van province climate data MLRM1, MLRM2 and MLRM3 models have been developed. The regression coefficient (R2), defined as the level of indication of the change in ETo, has been obtained as 0.95 for MLRM1, 0.99 for MLRM2 and MLRM3. Root mean square error (RMSE) as an indicator of the deviation of the ETô value estimated by the model from the ETo value determined by the FAO 56 Penman Monteith equation, has been determined 0.16 for the MLRM1, 0.12 for the MLRM2 and the MLRM3. It has been found that the models give healthier results in the determination of total plant water consumption (ΣETc) during the vegetation period rather than daily ETo estimation. Only the MLRM1 model with the lowest mean absolute percentage error (MAPE=10%) is recommended for daily ETo estimation. It is considered that all MLRM models can be used in ΣETc determination with a rate of 5-6 % MAPE and will be a good alternative because they are suitable for the region.

Keywords: Evapotranspiration, Air temperature, Relative humidity, Penman Monteith, Regression

DOI: 10.7176/JSTR/5-2-02