寒区湿地实际蒸散发动态特征及影响因素研究

Dynamic characteristics and influencing factors of actual evapotranspiration in cold wetland

为了解寒区湿地实际蒸散发(ETa)过程,有效利用水资源,基于哈尔滨金河湾湿地2015年8月-2016年7月涡度相关系统通量观测数据,分析了不同时间尺度下ETa变化规律及影响因素。研究期间年ETa为660mm,日最高值达8.1mm/d,夏季(3.4mm/d)最高,春季(2.3mm/d)、秋季(1.4mm/d)次之,冬季(0.1mm/d)偏低且变化平稳。5月生长期作物系数(Kc)由0.95增加到1.18左右,6月-8月中旬稳定期Kc在1.05~1.18之间,8月下旬-9月枯萎期Kc由1.05减小到0.85左右。影响ETa的主要气象因素为净辐射和饱和水汽压差。不同时间尺度下ETa与气象因子相关性略有不同:净辐射和水汽压差与ETa的相关性在两个尺度上均很显著,但30min尺度净辐射与ETa的相关性更高。温度与ETa的相关性在两个尺度上基本一致,高温促进ETa蒸散发而低温抑制ETa蒸散发。日尺度上空气湿度与ETa在秋、冬季相关性明显,30min尺度上春、冬季相关性明显。风速与ETa仅在30min尺度上夏、秋季有一定的相关性。

In order to understand the actual evapotranspiration(ETa)process in cold wetland and to make effective management of water resources,we analyzed the variation of ETain Harbin Jinhewan wetland and its influencing factors under different time scales based on the measured data of eddy covariance system from August 2015 to July 2016.The annual ETa was 660 mm during the study period,and the maximum daily ETa was up to 8.1 mm/d.The ETa was the highest in summer(3.4 mm/d),second highest in spring(2.3 mm/d)and autumn(1.4 mm/d),and was the lowest and stable in winter(0.1 mm/d).The crop coefficient(Kc)increased from 0.95 to about 1.18 in May(plant growing period).The Kc was between 1.05-1.18 from June to the middle of August(plant stabilizing period),and it decreased from 1.05 to 0.85 during late August to September(plant withering period).The main meteorological factors affecting the ETa were net radiation and vapor pressure deficit.The correlations between ETaand meteorological factors were different at different time scales.The correlations of net radiation and water vapor pressure deficit with ETa were significant at both scales,but net radiation was more correlated to ETaat the 30 min scale.The correlation between temperature and ETa was basically consistent at both scales.High temperature would promote ETaand low temperature would suppress ETa.At the daily scale,the correlation between air humidity and ETa was obvious in autumn and winter;at the 30 min scale,the correlation was obvious in spring and winter.The correlation between wind speed and ETa was only obvious in summer and autumn at the 30 min scale.