Modeling the effects of drip irrigation under plastic mulch on vapor and energy fluxes in oasis agroecosystems, Xinjiang, China
2019
Yuan, Xiuliang | Bai, Jie | Li, Longhui | Kurban, Alishir | De Maeyer, Philippe
Drip irrigation under plastic mulch is a common agricultural practice for oasis agroecosystems in the extensive arid regions of northwest China, and it is widely used to improve agricultural production by suppressing soil evaporation. The widespread application of plastic mulch has also obviously altered land characteristics and the partitioning of vapor and energy between the surface and the atmosphere. However, these physical processes, to date, are poorly incorporated into land surface models. In this study, an irrigation scheme and a plastic mulch module were incorporated into the Common Land Model (CoLM) to examine their influences on vapor (evapotranspiration) and energy fluxes, and the evapotranspiration observations were used to evaluate the model performance of irrigation effects. A sensitivity analysis indicates significant sensitivity relative to both the amount and timing of irrigation on vapor and energy fluxes. In addition, our results show that the revised CoLM with an irrigation module produced a better simulation of evapotranspiration than the default CoLM. However, large uncertainties still exist that fluctuation in simulated evapotranspiration is substantial, without considering the impact of plastic mulch. Incorporating the mulch module improved the CoLM performance for both vapor and energy fluxes. Plastic mulch reduced net radiation, sensible and latent heat fluxes. It aslo suppressed ground heat fluxes at daytime but improved ground heat fluxes at nighttime. Our results indicate that the agricultural practice, drip irrigation under plastic mulch, should be implemented into CoLM and other land surface models for studying vapor and energy fluxes in oasis agroecosystems or other similar agricultural ecosystems.
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