黄河流域水文站和气象站蒸发皿蒸发量时空变化及其差异

Temporal and Spatial Variation and Difference of Pan Evaporation Between Hydrological Station and Meteorological Station in the Yellow River Basin

黄河流域蒸发皿蒸发量的变化趋势、时空特征及其影响因子,对深入理解黄河流域气候变化影响下的水循环过程具有重要的科学意义。目前大多研究将气象站蒸发皿蒸发量作为基础,以此反映黄河流域的蒸发格局及其变化规律,忽略了水文站蒸发皿蒸发量的重要参考价值。基于黄河流域51个水文站及其邻近55个气象站1975—2018年蒸发皿蒸发量观测资料,采用Mann-Kendall趋势检验分析黄河流域及其8个二级水资源分区水文站和气象站蒸发皿蒸发量的差异、变化趋势与空间格局,并通过Spearman秩相关方法分析影响蒸发皿蒸发量变化的主控气象因子。结果表明:黄河流域水文站蒸发皿蒸发量普遍低于相邻的气象站,水文站多年平均蒸发皿蒸发量为866.2 mm,气象站为1 021.0 mm,水文站蒸发皿蒸发量比气象站平均低15.2%。黄河流域整体年均蒸发皿蒸发量呈显著下降趋势,水文站、气象站蒸发皿蒸发量的变化率分别为-1.2、-1.9 mm/a。水文站和气象站蒸发皿蒸发量在空间格局上变化相对一致,“蒸发悖论”主要存在于流域中下游,在流域上游龙羊峡以上区间、龙羊峡至兰州区间主要呈上升趋势,流域中下游主要呈下降趋势。驱动黄河流域蒸发皿蒸发量变化的主控因素不同,气温的上升和相对湿度的下降是流域上游龙羊峡以上区间、龙羊峡至兰州区间蒸发皿蒸发量上升的主要原因,而日照时数的减少和风速的下降是流域中下游蒸发皿蒸发量下降的主要原因。

The trends,temporal and spatial characteristics and influencing factors of pan evaporation in the Yellow River Basin are of great scientific significance for understanding the water cycle process under the influence of climate change in the Yellow River Basin.At present,most studies take pan evaporation of meteorological stations as the basis to reflect the evaporation pattern and its change rule of the Yellow River Basin,but ignore the important reference value of pan evaporation of hydrological stations.Based on the observation data of pan evaporation at 51 hydrological stations and 55 adjacent meteorological stations in the Yellow River Basin from 1975 to 2018,the differences,trends and spatial patterns of pan evaporation at hydrological stations and meteorological stations in the Yellow River Basin and its eight secondary water resources subregions were analyzed by using the MannKendall trend test.The main meteorological factors affecting pan evaporation were analyzed by Spearman rank correlation method.The results show that the pan evaporation of hydrological stations in the Yellow River Basin is generally lower than that of the adjacent meteorological stations.The average pan evaporation of hydrological stations is 866.2 mm,and that of meteorological stations is 1021.0mm,which is 15.2%lower than that of meteorological stations on average.The change rates of pan evaporation at hydrological and meteorological stations are-1.2 mm/a and-1.9 mm/a,respectively.The“evaporation paradox”mainly exists in the middle and lower reaches of the basin.In the upper reaches of the basin,above Longyangxia and from Longyangxia to Lanzhou,the pan evaporation mainly presents an upward trend,and in the middle and lower reaches of the basin,it mainly presents a downward trend.Driving evaporation pan evaporation in the Yellow River is the main controlling factors of different change,the rise of temperature and relative humidity of the decline is basin upstream results above,the results to the Lanzhou interval evaporation pan evaporation,the main reasons for the rising and falling of the sunshine duration and wind velocity is in the middle and lower reaches of river basin is the main reason for decline in evaporation pan evaporation.