Inter-seasonal and cross-treatment variability in single-crop coefficients for rice evapotranspiration estimation and their validation under drying-wetting cycle conditions

Yuping Lv, Junzeng Xu, Shihong Yang, Xiaoyin Liu, Jiangang Zhang and Yijiang Wang

Agricultural Water Management, 2018, vol. 196, issue C, 154-161

Abstract: A two-year experiment was conducted to investigate the inter-seasonal and cross-treatment variability in measured rice evapotranspiration (ETcMea), measured single-crop coefficients (KcMea), and treatment-specific calibrated coefficients (KcCal), under different drying-wetting cycles in a subtropical monsoon climate in East China. For each drying-wetting treatment, ETcMea was determined based on data collected in lysimeters, and KcMea was calculated from ETcMea, reference evapotranspiration, and soil moisture deficit coefficient. Following the single-crop coefficient method, KcCal was determined by matching KcMea. In 2012 and 2013, ETcMea varied from 459.5 to 486.7mm, and 544.5–605.1mm, respectively. Its inter-seasonal variability was larger than the cross-treatment variability. Stage-wise average KcMea were 1.07–1.17, 1.30–1.51, 1.49–1.54, and 1.17-1.29 in 2012, and 1.06–1.12, 1.31–1.49, 1.43–1.57, and 1.26–1.27 in 2013 during the initial, crop development, mid-season, and late season stages, respectively. Treatment-specific KcCal were calibrated as 1.09–1.20, 1.51–1.60, and 0.74–0.78 in 2012, and 1.05–1.14, 1.47–1.64, and 0.96–1.01 in 2013 for the initial, mid-season, and end-season stages, respectively. The inter-seasonal and cross-treatment variability in KcMea and KcCal was low. Each treatment-specific KcCal set performed similarly when rice ETc was calculated under different drying-wetting treatments. Cross validation indicated that large daily uncertainty in ETc estimation occurred when daily ETcMea was high, and uncertainty in seasonal ETc calculated using different treatment-specific KcCal sets ranged from 45.7 to 60.1mm (approximate to one irrigation). Calibrating KcCal using more data (season-specificKcCal or mixed treatment KcCal) would improve the accuracy of KcCal in ETc estimation.

Keywords: Variability; Cross validation; Single-crop coefficients; Drying-wetting cycles; Rice evapotranspiration; Uncertainty (search for similar items in EconPapers)
Date: 2018
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Citations: View citations in EconPapers (5)

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Persistent link: https://EconPapers.repec.org/RePEc:eee:agiwat:v:196:y:2018:i:c:p:154-161

DOI: 10.1016/j.agwat.2017.11.006

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