Arid Zone Research ›› 2022, Vol. 39 ›› Issue (5): 1564-1575.doi: 10.13866/j.azr.2022.05.21

• Land and Water Resources • Previous Articles     Next Articles

Spatial and temporal variability of evapotranspiration and influencing factors in the Ili River-Balkhash Lake Basin

YAO Jia1(),CHEN Qihui1,LI Qiongfang1,2(),CUI Gang1,ZHANG Liangjing3   

  1. 1. College of Hydrology and Water Resources, Hohai University, Nanjing 210098, Jiangsu, China
    2. Yangtze Institute for Conservation and Green Development, Nanjing 210098, Jiangsu, China
    3. College of Environment, Hohai University, Nanjing 210098, Jiangsu
  • Received:2022-04-18 Revised:2022-06-25 Online:2022-09-15 Published:2022-10-25
  • Contact: Qiongfang LI E-mail:2761566292@qq.com;qfli@hhu.edu.cn

Abstract:

From 2000 to 2020, remote sensing data, such as MODIS and FLDAS, the Mann-Kendall method, Theil-Sen median trend analysis, Pearson correlation analysis, and the water balance principle, were applied to explore the spatial distribution and temporal variation patterns of actual evapotranspiration in the Ili River-Balkhash Lake basin, along with its main influencing factors. In addition, changes in the ecosystem water supply were discussed. The results were as follows: (1) the upper, middle, and lower Ili River-Balkhash Lake basins had an average annual evapotranspiration of 439.0 mm, 317.9 mm, and 201.1 mm, respectively. The daily evapotranspiration in the upper and middle basins was the greatest in the summer, while the lower basin had the greatest daily evapotranspiration in the spring. The intra-annual distribution of evapotranspiration in the upper and middle basins was “unimodal,” with peaks in July and June, respectively. It was “bimodal” in the lower basin, with peaks in March and November, respectively. (2) The annual evapotranspiration increased in both the upper and lower basins, with the highest concentrations in the upper Ili River valley, Tianshan Mountains, and near the Ili River delta in the lower basin. Compared to the 2000s, the average annual evapotranspiration in the Ili River valley and Ili River delta increased by more than 10% in the 2010s. (3) Based on the Pearson correlation analysis, the upper and middle basins showed high positive correlations with temperature and NDVI, whereas the lower basin showed high positive correlations with soil moisture. (4) From 2000 to 2020, the basin's total water supply service decreased, with several shortfalls in the upper basin and shortfalls in the middle and lower basins beginning to appear in 2020. The balance of water supply and demand must be ensured by controlling the total amount of water being used and by improving water use efficiency.

Key words: Ili River-Balkhash Lake Basin, evapotranspiration, temporal and spatial changes, driving factors, Pearson correlation analysis.