Changes in Mean Annual and Seasonal Potential Evapotranspiration in AL Raqa During The Period 1975-2005

Hanan Abdo(1)*and Michael Skaf(1)

(1) Department of forestry and environment, Faculty of Agriculture, Tishreen University, Lattakia, Syria.

(*Corresponding author: Hanan Abdo. E-Mail:

Received: 7/07/2021                          Accepted: 22/12/2021


 Evapotranspiration is a major component of the water cycle and plays a key role in surface energy balance and has a significant agricultural and ecological implication. To evaluate temporal characteristic potential evapotranspiration, at annual and seasonal time scales in Alraqa station during the period 1975-2005, the enman-Monteith equation was applied to calculate monthly potential evapotranspiration (ETP) using meteorological data which include meaning maximum and minimum temperatures, relative humidity, winds speed, and sunlight duration. Trends with Mann – the Kendall test and point change analysis were used to detect significant changes in annual and seasonal ETP. The results showed a significant decreasing tendency in annual  ETP related to decreasing ETP in all seasons, especially in summer. Annual values of ETP were Shifted during two periods: 1984-1985 and 1990-1991. This  decreasing trend in ETP resulted  from westerly  wind direction   especially in warm months,  which promotes increasing relative humidity  in this region, owing to the location of Al Asad lake near this region

Keywords: Potential evapotranspiration, Climate change, Penman, Monteith, Syria.

Full paper in Arabic: pdf