Analysis of variation characteristics of reference crop evapotranspiration inimportant water source supply areas of the Yellow River
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DOI:10.7606/j.issn.1000-7601.2012.06.41
Key Words: reference crop evapotranspiration (ET0)  variation characteristic  Gannan pastoral area
Author NameAffiliation
WANG Zhigui Institute of Arid Meteorology, CMA, Key Laboratory of Arid Climatic Change and Reducing Disaster of Gansu Protince, Lanzhou, Gansu 730020, China
Gannan Meteorological Bureau, Hezuo, Gansu 747000, China 
WANG Suping Institute of Arid Meteorology, CMA, Key Laboratory of Arid Climatic Change and Reducing Disaster of Gansu Protince, Lanzhou, Gansu 730020, China 
WANG Jianbing Gannan Meteorological Bureau, Hezuo, Gansu 747000, China 
ZHANG Shengzhi Gannan Meteorological Bureau, Hezuo, Gansu 747000, China 
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Abstract:
      Because of natural and human factors, in recent years the grassland ecology of the upper reaches of the Yellow River was badly damaged by grassland degradation, desertification, and even some places the phenomenon such as water resources exhausted. Reference crop evapo-transpiration amount (ET0) changes and have great influence on the water resources and ecological status, so the pastoral areas of Gannan ET0 change characteristics are analyzed, and fur-ther research is carried out on whether the effeet of plateau meteorological factors is significant on ET0 of the pastoral ar-eas. The meteorological data from 4 observatory stations in Gannan pastoral areas in 1971-2010 years are used to calcu-late ET0 value of pastoral area from month to month with Penman-Monteith formula. Through statistical analysis, correla-tion analysis, small affected Mann-Kendall method, it is found that interannual variability of ET0in Gannan pastoral ar-eas increases year by year, rising to 8.8~19.5 mm/10a; it shows a obvious 10-year cycle before 1985 while a 5-year cycle from 2000-2010; and it appears a faster rise in the recent 20 years since the 1990s, and even a sudden increase after 1996. The ET0 of pastoral areas in summer is the largest and rises fastest year after year; while it in winter is the minimum and rises slowest yearby year. The uneven spatial distribution of ET0 in pastoral areas is related not only to the complexity of local special plateau topography, but also to the difference of main meteorological factors influencing the amount of evapo-transpiration.