ANN-based PCA to predict evapotranspiration: a case study in India

Abstract

The Penman–Monteith evapotranspiration (ET) model has superior predictive ability to other methods, but it is challenging to apply in several Indian stations, owing to the need for a large number of climatic variables. The study investigated an artificial neural network (ANN) model for calculating ET for various agro-climatic regions of India. Sensitivity analysis showed that the overall average changes in ET0 values for 25% change in the climatic variables were 18, 16, 14, 7, 5, and 4%, respectively, for Tmax, RHmean, Rn, wind speed, Tmin, and sunshine hours. The dominant climatic variables were identified from the principal component analysis (PCA) and ET0 was computed using an ANN with dominant climatic variables. The ANN architecture with backpropagation technique had one hidden layer and neurons ranging from 10 to 30 for all climatic variables and from 5 to 10 for PCA variables. The new ET models were statistically compared with Penman–Monteith ET estimate, and found reliable. PCA variables guaranteed an estimate of ET0 accounting for 98% of the variability. The average values of coefficient of determination, standard error of estimate, and percentage efficiency were observed as 0.96, 0.24, and 94%, respectively. HIGHLIGHTS The Penman–Monteith ET model is the standard but data-intensive, so its applicability is limited.; The crucial climatic variables influencing ET are identified for various agro-climatic regions using principal component analysis and sensitivity analysis.; New ET models are developed and compared with the standard Penman–Monteith ET estimate.; Less data-intensive ANN models are proven to be acceptable in estimating ET0.;

Keywords

• agro-climatic regions
• ann models
• evapotranspiration
• penman–monteith model
• principal component analysis