ABSTRACT
Meteorological Variables ............................................................... 28 2.4.1 Mann-Kendall Test ............................................................. 28 2.4.2 Slope Estimator .................................................................. 29 2.5 Results and Discussion .................................................................. 29 2.5.1 Estimation of ET0 ............................................................... 29 2.5.1.1 Annual ET0 .......................................................... 29 2.5.1.2 Monthly ET0 ........................................................ 32 2.5.2 Investigation of Trends in ET0............................................ 33
2.5.3 Influence of Meteorological Parameters on ET0 Changes ............................................... 34
2.6 Conclusions .................................................................................... 36 2.7 Summary ........................................................................................ 37 Acknowledgments ................................................................................... 37 Keywords ................................................................................................ 38 References ............................................................................................... 38
2.1 INTRODUCTION
Evapotranspiration (ET) is frequently used in the analysis of regional water studies, field irrigation practices, weather forecasting, etc., owing to the results of impacts of ET changes, which is seriously affecting water use efficiency. The ET, one of the basic components of the hydrologic cycle, is combination of two processes (evaporation and transpiration), which balances the nature. For estimating the ET these two processes need to be checked upon, i.e., amount of water lost to the atmosphere from soil surface by the process of evaporation, as well as the water contained in the stomatal tissues of the sparse vegetation available in arid region that is released to the atmosphere as water vapor by the process of transpiration.
