Comparison of Different Methods to Estimate Mean Daily Evapotranspiration from Weekly Data at Patna, India

Crop water requirement mainly depends upon crop sowing date, crop growth stages, crop duration and climatic conditions during the growing season of an individual crop. A good estimate of evapotranspiration is essential for water balance irrigation scheduling and water resource planning and management. Since, direct measurement of ET₀ is difficult and time consuming, so most common practice is to estimate ET₀ from meteorological data available for the area employing empirical equations. 

There are numerous evapotranspiration equations developed and used by researchers but still there is confusion in selecting the reliable evapotranspiration estimation method for the area concerned. Some authors compared estimates of different ET₀ estimation methods for different regions of the world. Al-Ghobari compared five different methods: FAO-Penman, Jensen- Haise, Blaney and Criddle, Pan Evaporation and calibrated FAO-Penman for four areas under local conditions of Saudi Arabia. The results showed that estimated ET values were highly correlated with measured evapotranspiration values. (Read more)