中国科学院水利部水土保持研究所机构知识库

Potential evapotranspiration (ET0) is an essential component of the hydrological cycle, and
quantitative estimation of the influence of meteorological factors on ET0 can provide a scientific
basis for studying the impact mechanisms of climate change. In the present research, the Penman–
Monteith method was used to calculate ET0. The Mann–Kendall statistical test with the inverse distance
weighting were used to analyze the spatiotemporal characteristics of the sensitivity coefficients
and contribution rates of meteorological factors to ET0 to identify the mechanisms underlying
changing ET0 rates. The results showed that the average ET0 for the Yanhe River Basin, China from
1978–2017 was 935.92 mm. Save for a single location (Ganquan), ET0 increased over the study period.
Generally, the sensitivity coefficients of air temperature (0.08), wind speed at 2 m (0.19), and solar
radiation (0.42) were positive, while that of relative humidity was negative (−0.41), although significant
spatiotemporal differences were observed. Increasing air temperature and solar radiation contributed
1.09% and 0.55% of the observed rising ET0 rates, respectively; whereas decreasing wind
speed contributed −0.63%, and relative humidity accounted for −0.85%. Therefore, it was concluded
that the decrease of relative humidity did not cause the observed ET0 increase in the basin. The
predominant factor driving increasing ET0 was rising air temperatures, but this too varied significantly
by location and time (intra‐ and interannually). Decreasing wind speed at Ganquan Station
decreased ET0 by −9.16%, and was the primary factor underlying the observed, local “evaporation
paradox”. Generally, increase in ET0 was driven by air temperature, wind speed and solar radiation,
whereas decrease was derived from relative humidity.