Evaporation is the key to the basin’s water cycle. Agricultural
irrigation has resulted in a significant variation of regional potential
evaporation (Epen). The spatiotemporal variation of
Epen and the influencing factors in the natural,
agricultural, and desert areas in different developmental stages of
irrigation in the Heihe River Basin (HRB) from 1970 to 2017 are
comparatively analyzed in this study. This work focused on the
correction effect of irrigation on the variation of
Epen. The agricultural water consumption in HRB
significantly varied around 1998 due to the agricultural development and
water policy. Under the influence of irrigation, the annual variation of
Epen in the agricultural, natural, and desert areas was
significantly different. From 1970 to 1998, the annual trend slope of
Epen in the natural area only reduced by 1 mm
decade-1, while that in the agricultural area
significantly decreased by 39 mm decade-1. After the
implementation of water-saving irrigation, the Epen in
the natural and agricultural areas increased by 11 and 54 mm
decade-1, respectively, from 1998 to 2017. In contrast
with the natural and agricultural areas, Epen in the
desert area decreased by 80 mm decade-1 from 1970 to
1998 and continuously decreased by 41 mm decade-1 from
1998 to 2017. However, the regulatory effect of irrigation on
Epen in the desert area started to manifest due to the
expansion of the cultivated land area in the desert area from 2010 to
2017. Irrigation has a significant regulatory effect on the variation of
Epen in HRB. The regulatory effect is mainly reflected
on the aerodynamic term (Eaero). The analytical results
of the main meteorological factors affecting Epen in different regions
indicated that the main meteorological factors influencing the variation
of Epen in each region are the wind speed 2 m above the
surface (U2) and the water vapor pressure difference
(VPD).