Weekly pan evaporation estimation by Stephens-Stewart and Griffith models

Stephens-Stewart model (SSM), and Griffith’s model (GM) were used to estimate the weekly pan evaporation (EPW) at Pantnagar, located at the foothills of Himalayas in the Uttarakhand state of India. Weekly meteorological data of maximum and minimum air temperatures, relative humidity in the morning (7 AM) and afternoon (2 PM), wind speed, sunshine hours and pan evaporation from January 2004 to December 2007 were used. The best combination of input variables models were decided using the Gamma Test (GT). The estimated values of EPW by the Stephens-Stewart and Griffith’s model were compared with observed values of EPW based on statistical indices such as root mean squared error (RMSE), coefficient of efficiency (CE) and correlation coefficient (r).