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Historical pan evaporation changes in the Qiantang River Basin, East China
Author(s) -
Xu YuePing,
Pan Suli,
Gao Chao,
Fu Guangtao,
Chiang YenMing
Publication year - 2015
Publication title -
international journal of climatology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.58
H-Index - 166
eISSN - 1097-0088
pISSN - 0899-8418
DOI - 10.1002/joc.4470
Subject(s) - environmental science , pan evaporation , climatology , trend analysis , structural basin , climate change , wind speed , relative humidity , water cycle , drainage basin , humidity , evaporation , meteorology , geography , oceanography , geology , cartography , paleontology , ecology , machine learning , computer science , biology
Pan evaporation ( E pa ) has been decreasing in many regions of the world in the past decades. Analysis of the changes in E pa helps to understand the variation of vapour in the hydrological cycle and the impact of climate change on E pa . This study aims to investigate the spatial and temporal trends in E pa and analyse the causes of E pa variation in the Qiantang River Basin, East China. A self‐organizing map neural network is first applied to classify the 40 hydrological stations. Based on the clustering results, a trend‐free pre‐whitening Mann–Kendall test is then used to investigate the historical trends in E pa based on more than 50 years of monthly observations. Finally, sensitivity analysis is conducted for evaluating the relationship between E pa and five climate variables and for investigating the causes of changes in E pa using a global, variance‐based method. It is found that the hydrological stations located in this basin can be classified into six sub‐areas and the E pa trends vary substantially at six sub‐areas. Generally, there is a decreasing trend of E pa in a majority of months in all sub‐areas except one and the most significant decreases occur in summer. The results of sensitivity analysis reveal that E pa is more sensitive to solar radiation, followed by minimum air temperature, wind speed, relative humidity and maximum air temperature. The contribution of interactions between different climate variables to the variation of E pa cannot be ignored in some specific stations. Overall, the change of E pa is mainly due to the decrease of solar radiation. This study provides an in‐depth understanding of the causes of E pa variation and valuable information for sustainable water and crop management in this region.