Sustainable Water Resources Management

, Volume 5, Issue 4, pp 1981–1994 | Cite as

Trend analysis of evapotranspiration applying parametric and non-parametric techniques (case study: arid regions of southern Iran)

  • Mehdi BahramiEmail author
  • Abdol Rassoul Zarei
  • Mohammad Mehdi Moghimi
  • Mohammad Reza Mahmoudi
Original Article


Evapotranspiration, as the main component of the hydrologic cycle, will affect plant water demands and water resources plan. The aims of present research were to evaluate the tendency in reference evapotranspiration (ET0) by the Mann–Kendall test, the Spearman’s Rho test and the linear regression analysis at the 5% significant level using meteorological data of 16 synoptic stations at Southern Iran during period 1980–2010. Results revealed that 1, 3, 6, and 12 monthly ET0 in most regions of study area showed increasing trends. Only, Shiraz station exhibited the significant decreasing trend in all time scales based on statistical methods. The values of the significant raising tendencies in annual ET0 varied among − 0.501 at Shiraz and + 3.194 mm/year at Bam. Based on seasonal time scale, also Bam station showed the maximum significant increasing tendency (in summer and spring) based on Mann–Kendall and Spearman’s Rho techniques. The monthly analysis of trend in ET0 series indicated that the highest amounts of stations with significant increase tendency discovered in May. In general, this study result indicates a serious warning about warming and climate change of southern Iran. This subject can cause different effects including increment of water consumption in agricultural sector, increase of water rain waste, enhancement of water waste in dams, reservoirs, lakes, etc., decrease of surface water quality, and food crisis.


Mann–Kendall Evapotranspiration Trend analysis Spearman Rho test Linear regression Iran 



The authors would like to thank national meteorological organization of Iran and water organization of Fars province for providing the meteorological data.

Compliance with ethical standards

Conflict of interest

The authors declare that they have no conflict of interest.


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Copyright information

© Springer Nature Switzerland AG 2019

Authors and Affiliations

  • Mehdi Bahrami
    • 1
    Email author
  • Abdol Rassoul Zarei
    • 2
  • Mohammad Mehdi Moghimi
    • 1
  • Mohammad Reza Mahmoudi
    • 3
  1. 1.Department of Water Engineering, Faculty of AgricultureFasa UniversityFasaIran
  2. 2.Department of Range and Watershed Management (Nature Engineering), Faculty of AgricultureFasa UniversityFasaIran
  3. 3.Department of Statistical Sciences, Faculty of ScienceFasa UniversityFasaIran

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