Contribution of meteorological variables to changes in potential evaporation in Haihe River Basin, China

Potential evaporation (ETp) is influenced by meteorological variables such as net radiation, wind speed, relative humidity and air temperature. Therefore, changes in ETp directly reflect climate change and can be used to diagnose the water requirement of different regions. This study addresses the contribution of select meteorological variables to changes in ETp in Haihe River Basin in China from 1959 to 2008 by sensitive analysis, attribution analysis and relative changes method. The results show that: (i) The ETp presented positive and negative trends during 1959-1998 and 1999-2008, respectively, which resulted in a slightly overall decreasing trend from 1959-2008; (ii) The sensitivity coefficients estimated using sensitive analysis presented clear spatial differences for each variable with the ETp being most sensitive to relative humidity, followed by net radiation, air temperature and wind speed; (iii) By the relative changes method, the ETp, was most sensitive to net radiation, followed by relative humidity, air temperature and wind speed; (iv) Interestingly, the attribution analysis of changes of ETp showed that air temperature, wind speed, relative humidity and net radiation affected ETp in decreasing order of magnitude from 1959-1998 whereas from 1999-2008, relative humidity, air temperature, wind speed and net radiation affected ETp in decreasing order of magnitude. This differential contribution of the variables to changes in ETp over time could explain the slightly decreasing trend in ETp from 1959-2008. Furthermore, this indicates that attribution analysis can draw a clear picture of how climate change impacts changes in ETp. This may provide insights into water resources management in the non-humid region, the Haihe River basin, China. (C) 2011 Published by Elsevier B. V. Selection and/or peer-review under responsibility of School of Environment, Beijing Normal University.