AUTHOR=Su Yuexia , Wang Jian , Li Junhong , Wang Lizhi , Wang Kunfeng , Li Ao , Gao Lei , Wang Zhanbiao 

TITLE=Spatiotemporal changes and driving factors of reference evapotranspiration and crop evapotranspiration for cotton production in China from 1960 to 2019

JOURNAL=Frontiers in Environmental Science

VOLUME=11

YEAR=2023

URL=https://www.frontiersin.org/journals/environmental-science/articles/10.3389/fenvs.2023.1251789

DOI=10.3389/fenvs.2023.1251789

ISSN=2296-665X

ABSTRACT=<p><bold>Introduction:</bold> Understanding and tracking changes in crop water requirements is crucial for effective irrigation, water planning, and future decisions. Determining the reference evapotranspiration (ET<sub>O</sub>) and crop evapotranspiration (ET<sub>C</sub>) of China cotton is essential for water resource management.</p><p><bold>Methods:</bold> This study analyzed the spatiotemporal changes in ET<sub>O</sub> and ET<sub>C</sub> at 248 standard stations in cotton production regions of China from 1960 to 2019, and the ET<sub>O</sub> and ET<sub>C</sub> of each station were quantified by using the CropWat 8.0 and non-parametric Mann-Kendall test. The impacts of climate change on ET<sub>O</sub> and ET<sub>C</sub> were evaluated by analyzing the contribution rate and sensitivity coefficient of climate change.</p><p><bold>Discussion:</bold> The results revealed distinct distributions of ET<sub>O</sub> and ET<sub>C</sub> across various growth stages and spatial scales in the cotton production regions of China. In the Huanghe Valley, the rate of decline for ET<sub>O</sub> decreased from 787.23 mm to 769.84 mm, while in the Yangtze Valley cotton region, it decreased from 749.19 mm to 735.01 mm. Similarly, in the Northwest inland cotton regions, the rate of decline for ET<sub>O</sub> reduced from 991.19 mm to 982.70 mm. As for ET<sub>C</sub>, the rate of decline decreased from 677.62 mm to 654.33 mm in the Huanghe Valley, from 653.02 mm to 625.50 mm in the Yangtze Valley, and from 916.25 mm to 886.74 mm in the Northwest inland cotton regions. ET<sub>O</sub> was highly sensitive to maximum air temperature (T<sub>max</sub>), followed by relative humidity (RH), sunshine duration (SD), wind speed at 2 m height (WS), and minimum air temperature (T<sub>min</sub>). WS was the most influential climate variable associated with ET<sub>O</sub> change, followed by T<sub>max</sub>, SD, RH, and T<sub>min</sub>. Significant declines in WS and SD were indicated in the decrease in ET<sub>O</sub> in the Huanghe Valley and Yangtze Valley cotton regions. WS showed a significant decrease in ET<sub>O</sub> in the northwestern inland cotton region. However, decreased RH and increased temperature commonly reversed the trend of ET<sub>O</sub> from 2000 to 2019, and the northwestern inland cotton region had the most significant upward trend. Amidst high temperatures and drought stress, the irrigation needs of cotton were rising, posing a significant threat to both cotton production and water resources.</p>