Changes in Reference Evapotranspiration over Southwest China during 1960–2018: Attributions and Implications for Drought

Abstract

Reference evapotranspiration (ET0) is important to the global energy balance and to hydrological cycling. However, the extent to which ET0 changes, the main driving factors, and especially the implications of its shift for drought in Southwest China are not clear. In this study, trends in Penman–Monteith ET0 and other climatic parameters at 79 stations in Southwest China from 1960 to 2018 were investigated by using the Mann–Kendall test. Furthermore, partial correlation analysis and multiple linear regression were used to determine the dominant climate driving factors in changes in ET0. The relative contribution of precipitation and ET0 to drought duration was also quantified based on spatial multiple linear regression. Results revealed that annual ET0 decreased significantly (p < 0.01) at a rate of 14.1 mm per decade from 1960 to 2000, and this decrease disappeared around 2000. For the entire study period, the sunshine duration (Tsun) was the most closely correlated with and played a dominant role in the variations in ET0 at both annual and seasonal (summer and autumn) timescales, whereas the relative humidity was the most dominant factor in the spring and winter. Trends in the Standardized Precipitation Evapotranspiration Index revealed that drought has become more serious in Southwest China, and ET0 has made a greater contribution to the duration of drought than precipitation. Our findings highlight that more attention should be paid to the impacts of ET0 changes on drought in Southwest China. Furthermore, these results can provide a reference for the allocation of water resources and the implementation of countermeasures to climate change.

Trend and Sensitivity Analysis of Reference Evapotranspiration in the Senegal River Basin Using NASA Meteorological Data

“…Overall, wind speed is the only variable that decreases significantly on an annual scale and during the rainy period. Similar results have been obtained by Zeng et al [69] who observed a significant decrease in wind speed during the period 1960-2018 in southwest China. In addition, Oguntunde et al [70] also found a significant decrease in wind speed over the 1973-2008 period in Nigeria.…”

Assessment of spatiotemporal variability and trend analysis of reference crop evapotranspiration for the southern region of Peninsular India

“…(Liu et al 2017) found out that wind speed did not have signi cant effect on the ET 0 values at the stations of Yellow River catchment which supports the results obtained by the current work. A past research (Zeng et al 2019) found that wind speed decreased for most of the 79 stations of south west China on the entire study duration and had very minor contribution to the variations of annual ET 0 values, which again is in accordance with the outcomes of the existing work.…”

A Multi-Index Evaluation of Drought Characteristics in the Yarlung Zangbo River Basin of Tibetan Plateau, Southwest China

“…Feng and Fu (2013) considered the rising temperature as the main reason of global drought. Zeng et al (2019) attributed the spring and winter drought to a decrease in relative humidity which led to an increase in reference evapotranspiration, while the duration of sunshine was the dominant factor of summer and autumn drought in southwest China from 1960 to 2000. In addition, soil drought (low soil moisture) and atmospheric aridity (high vapor pressure deficit, VPD) have been regarded as the two main factors responsible for drought, which influenced terrestrial water use and carbon uptake further (Novick et al, 2016;Zhou et al, 2019b).…”