Estimation of potential evapotranspiration using a single weather element -The evaporation

Abstract

Knowledge of potential evapotranspiration is a basic requirement in any study related to crop water management Observing the conceptual similarity between potential evapotranspiration and evaporation an attempt has been made to establish a linear relationship between the two.

Using 10 years potential evapotranspiration and evaporation data, linear regression analysis was carried out. Three stations, namely, Bangalore, Pune and Hissar in different latitude belts were selected for the present study. It was observed that partitioning of the annual period into dry and wet periods gives better results. Analysis of l0 years data for dry as well as wet period shows that correlation coefficient is more than 0.95 and variance of residual is very small for each data set.

Using the linear regression equation, potential evapotranspiration values were predicted for independent data set. It was found that correlation coefficient between estimated and observed potential evapotranspiration exceeds 0.90, implying that more than 80% of the variation in potential evapotranspiration can be explained by this simple method. Error analysis and also Chi-square test show that predicted values are quite close to observed values.