| 摘要: |
| 水面蒸发和植被蒸腾是湿地水平衡的关键要素，如何定量湿地的植被蒸腾速率是水文学领域的难题。本研究采用涡度协方差系统获得白洋淀典型部位2022年芦苇生长季（4-10月）蒸散速率(ET)为6.75 mm/d, 显著大于参考作物蒸散速率(ET0)5.06 mm/d。结合蒸发池获得的无植被区水面蒸发速率（Ew）均值3.22 mm/d和遥感方法识别的植被覆盖率65%等信息，计算发现植被覆盖区蒸散速率（ETc）均值为8.65 mm/d，是Ew均值的2.7倍。由于植被覆盖区蒸散主要由植被蒸腾控制，ETc在月尺度与对应观测范围的NDVI呈线性关系，指示与植被生长阶段密切相关。在生长季前期（4月1日至5月18日），ETc由4.19 mm/d逐渐增大至9.76 mm/d，均值为6.86 mm/d，对应作物系数Kc（ETc与ET0的比值）为1.01；在快速生长阶段（5月19日至6月24日），ETc介于9.88 mm/d-13.00 mm/d，均值为11.73 mm/d，对应作物系数Kc为1.77；在成熟阶段（6月25日至9月30日），ETc介于8.19-9.96 mm/d，均值为9.19 mm/d，对应作物系数Kc为1.74；而在衰老阶段（10月1日至10月31日），ETc由8.16 mm/d快速减小到3.58 mm/d，均值为5.66 mm/d，对应作物系数Kc为1.80。本研究获得的植被覆盖区蒸散速率及作物系数可为白洋淀水量平衡分析和雄安新区水资源安全保障提供科学依据。 |
| 关键词: 植被蒸腾 水面蒸发 涡度协方差系统 作物系数 水平衡 白洋淀 雄安新区 |
| DOI： |
| 分类号: |
| 基金项目:科技部科技创新专项项目(2022XACX0900) |
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| A study on evapotranspiration rate in the Baiyangdian wetland based on the eddy covariance technique |
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Yang Lei1, Jiang Xiaowei1, Zhang Zhiyuan1, Han Pengfei1, Ouyang Kaigao1, Gao Bing1, Zhang Yuan2, Li Haitao2
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1.MWR Key Laboratory of Groundwater Conservation,China University of Geosciences;2.China Institute of Geo-Environmental Monitoring
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| Abstract: |
| Water surface evaporation and vegetation transpiration are key elements of wetland water balance, and quantifying the vegetation transpiration rate of wetlands is a challenge in the field of hydrology. In this study, in typical parts of the Baiyangdian Lake during the 2022 reed growth season (from April to October), the average evapotranspiration rate (ET) obtained by using the eddy covariance system is found to be 6.75 mm/d, which is higher than the average reference evapotranspiration rate (ET0) equaling 5.06 mm/d. By combining the average water surface evaporation rate (Ew) equaling 3.22 mm/d obtained from the evaporation pool in non-vegetated areas and the vegetation coverage rate equaling 65% identified by using remote sensing images, the average evapotranspiration rate (ETc) in vegetation-covered areas is found to be 8.65 mm/d, which is 2.7 times higher than the average Ew. Because evapotranspiration in vegetation-covered areas is mainly controlled by vegetation transpiration, ETc has a linear relationship with NDVI on the monthly scale, indicating the control of vegetation growth stages. During the early growing season (from April 1st to May 18th), ETc increases from 4.19 mm/d to 9.76 mm/d, with an average ETc of 6.86 mm/d and a crop coefficient (Kc= ETc / ET0) of 1.01. In the rapid growing stage (from May 19th to June 24th), ETc ranges from 9.88 mm/d to 13.00 mm/d, with an average ETc of 11.73 mm/d and a Kc of 1.77. In the mature stage (from June 25th to September 30th), ETc ranges from 8.19 mm/d to 9.96 mm/d, with an average ETc of 9.19 mm/d and a Kc of 1.74. In the stage of plant senescence (from October 1st to October 31st), ETc rapidly decreased from 8.16 mm/d to 3.58 mm/d, with an average ETc of 5.66 mm/d and a Kc of 1.80. The evapotranspiration rate in vegetation-covered areas and crop coefficient obtained in this study can provide scientific basis for the analysis of water balance in the Baiyangdian Lake and the security of water resources in the Xiong"an New Area. |
| Key words: Vegetation transpiration Water surface evaporation Eddy covariance system Crop coefficient Water balance The Baiyangdian Lake the Xiong |
