Background Water evaporation plays an important role in the hydrological process as it is a major part of the ecological water balance. The evapotranspiration (E_T) is the loss of water from the soil both by evaporation and by transpiration from the plants growing thereon. Actual evaporation (E_a) concerns the water evaporation from natural surfaces to the atmosphere. Potential evaporation (E_p) is the amount of water that would be evaporated and transpired if there are sufficient water available. This demand incorporates the energy available for evaporation and the ability of the lower atmosphere to transport evaporated moisture away from the land surface. Therefore, the evaporation can substantially influence on a regional scale the amount and spatial distribution of water resources. In-depth understanding the spatio-temporal distribution and evolution process of evaporation provides scientific basis for basin water resources planning, evaluating the condition of drought, study on ecological water demand, etc.

Methods The spatio-temporal distribution characteristics and evolution trend of E_a and E_p were studied by linear trend analysis and relative variation ratio using MOD16 product and observation data of meteorological station during 2000-2014 in Ebinur Lake Basin.

Results 1) Inter-annual variation of E_a and E_p was not obvious during recent 15 years, the mean annual E_a and E_p were 315.76 and 1 555.27 mm respectively, and the great discrepancy between mean annual E_a and E_p showed that the whole study area was in the condition of water shortage and drought. 2) The spatial distribution of E_a was opposite to that of E_p. The northwestern mountain area, Jinghe-Bole Oasis area, western branch of northern Tianshan Mountain and Mayili Mountain area had sufficient water supply, while the most eastern area of Ebinur Lake Basin, all around of Jinghe-Bole oasis suffered from drought and water shortage. 3) Analysis of influencing factors demonstrated that temperature was the most important factor to affecting the spatio-temporal distribution of E_a and E_p in the study area. 4) The evolution trend of E_a was decreasing in the fifteen years, and the area with decreasing trend was accounted for 50% of the total. The evolution trend of E_p was increasing in the fifteen years, and the area with increasing trend was accounted for 48.39% of the total. The evolution trend of decreasing E_a and increasing E_p indicated that the condition of drought was aggravated during 2000-2014 in Ebinur Lake Basin.

Conclusions According to the spatio-temporal variation and evolution trend of E_a and E_p in Ebinur Lake Basin during 2000-2014, the land surface in Ebinur Lake Basin was drought, and the condition was aggravated year by year.