黄河三角洲湿地蒸散发量估算及时空演变规律分析

Estimation of Evapotranspiration and Analysis of Its Temporal and Spatial Evolution in Yellow River Delta Wetland

蒸散发过程是水文循环与地表能量平衡的关键环节,准确估算蒸散发量对于认识气候变化和水文循环过程具有重要意义。以黄河三角洲湿地为研究区,基于地表能量平衡理论和SEBAL模型,选用2000年、2003年、2005年、2008年、2011年、2014年、2017年、2020年共8年期的Landsat遥感影像对黄河三角洲湿地蒸散发量进行了反演估算,采用不同时间尺度下的蒸散发量扩展方法得到日、月蒸散发量,在此基础上完成了对反演结果的精度验证,并系统分析了黄河三角洲湿地蒸散发时空演变规律。结果表明:SEBAL模型具有较高的精度,反演误差均值在15%以内;黄河三角洲湿地夏季月蒸散发量大于100 mm,其中7月份和8月份日蒸散发量的变化范围为2~5 mm,9月份日蒸散发量的变化范围为1~4 mm;三角洲湿地南北区域的蒸散发量具有显著差异性,总体上呈现北部高、南部低的变化趋势;风速、平均气压和平均气温是影响黄河三角洲湿地蒸散发量变化的主要气象因素,与蒸散发量之间存在显著的相关性。研究结果可为黄河三角洲湿地水热通量研究提供参考,对湿地系统恢复自然修复能力具有重要的科学价值。

The evapotranspiration process is a key link in the hydrological cycle and surface energy balance,and accurate estimation of evapotranspiration is of great significance for understanding climate change and hydrological cycle processes.Taking Yellow River Delta wetland as the study area,based on the surface energy balance theory and the SEBAL model,this paper uses Landsat remote sensing images of eight years in 2000,2003,2005,2008,2011,2014,2017 and 2020 to inversely estimate the evapotranspiration of Yellow River Delta wetland.The daily and monthly evapotranspiration is obtained by using the evapotranspiration expansion method under different time scales.On this basis,the accuracy verification of the inversion results is completed,and the spatial-temporal evolution law of evapotranspiration in Yellow River Delta wetland is systematically analyzed.The research results are as follows.The SEBAL model has high accuracy,with an average inversion error of less than 15%.The monthly evapotranspiration of Yellow River Delta wetland in summer is more than 100 mm,of which the variation range of daily evapotranspiration in July and August is 2 mm to 5 mm,and that in September is 1 mm to 4 mm.There is a significant difference in evapotranspiration between the north and south regions of the delta wetland,with an overall trend of high in the north and low in the south.Wind speed,average air pressure and average temperature are the main meteorological factors affecting the change of wetland evapotranspiration in the Yellow River Delta,and there is a significant correlation with evapotranspiration.The research results can provide reference for the study of water and heat flux in Yellow River Delta wetland,and have important scientific value for the restoration of natural restoration capacity of wetland system.