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| DOI：10.13522/j.cnki.ggps.20180243 |
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| Multi-scale Analysis of Change in Reference Crop Water Demand in Yulin from 1959 to 2015 |
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LI Dachi, ZHANG Xin*, CHANG Haohao, YU Chengfeng
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College of Water Resources and Architectural Engineering, Northwest A & F University, Yangling 712100, China
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| Abstract: |
| 【Objective】 Crop demand for water is postulated to grow due to climate change. This paper analyzed the reference crop evapotranspiration (ET0) and its sensitivity to different metrological factors caused by climate change in Yulin city.【Method】We first calculated the ET0 using the Penman's formula and the meteorological data measured from 1959 to 2014, and then analyzed its variation at multiple temporal and spatial scales using the Mann-Kendall test and wavelet analysis method.【Result】The annual ET0 from 1959—2014 was in rise at average rates of 30.8 mm/10a, 11.4 mm/10a, 5.7 mm/10a, 6.7 mm/10a and 6.9 mm/10a, during different periods. Annual ET0 saw a dramatic change in 1995, and the seasonal ET0 in spring, summer and autumn all saw an abrupt change in 1998; winter ET0 in 1989 differed considerably from other years. The analysis showed that the main periodic cycle of the annual ET0 was 26 a, and the cycle of the four seasonal ET0 was 27 a, 28 a, 30 a and 27 a, respectively. Inside the main cycles, there were two further cycles with different periodic time. The correlation coefficient of ET0 with average relative humidity, sunshine hours, average temperature, average wind speed and annual mean surface temperature was -0.128, 0.223, 0.935, 0.271, 0.940, respectively.【Conclusion】ET0 at different time scales at Yulin had been in rise from 1959 to 2014, and the average temperature and the annual average surface temperature are the main factors that attributed the rise in ET0. |
| Key words: reference crop evapotranspiration (ET0); Penman formula; wavelet analysis; correlation analysis; Climate change |
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