| 英文摘要： |
Understanding the variation characteristics and related determining factors of water requirements under climate change is crucial for crop production and agricultural water resource utilization. Therefore, in this study, the crop coefficient method and water balance model were employed to estimate the crop water requirement (CWR) and irrigation water requirement (IR) of winter wheat in the middle reaches of the Yarlung Zangbo River (YZR) and its two tributaries from 1981 to 2015. The impacts of different meteorological factors on the CWR and IR variations were explored using sensitivity and contribution analyses, and their determining factors were identified. The results showed that effective precipitation increased at a rate of 0.98 mm/year from 1981 to 2015. Meanwhile, the CWR and IR decreased significantly at -2.27 mm/year and -3.26 mm/year, respectively, with annual mean values of 620 mm and 499 mm, respectively. The CWR exhibited relatively high sensitivities to sunshine duration and wind speed, indicating that these factors were more likely to cause changes in the CWR, of which wind speed was the determining factor of the CWR variation because of its high sensitivity and substantial reduction. While increased temperature caused an increase in the CWR, its influence was relatively limited and was offset by the impact caused by other factors. Meanwhile, the determining factor of the IR variation was the CWR (contribution rate of 83.11%), and the contribution of effective precipitation was only 16.89%. Nevertheless, spatial differences existed in the CWR and IR variations and corresponding determining factors. As it is necessary to understand the impacts of climate change on water requirements for effective agricultural water resource utilization, the results of this study will provide valuable information for mitigating the impacts of climate change and improving agricultural water management in the YZR and its two tributaries. |
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