Actual and Reference Evapotranspiration in a Cornfield in the Zhangye Oasis, Northwestern China

Gu, Lianglei; Hu, Zeyong; Yao, Jimin; Sun, Guojun

doi:10.3390/w9070499

Cited by 13 publications

(10 citation statements)

References 52 publications

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“…Li et al [70] reported a range from 1.5-6.5 mm day -1 during the growing season of maize in northwest China, while, Chávez et al [71] found values in the range of 2.5-6.5 mm day −1 during the one month SMACEX and SMEX02 campaigns. Tyagi et al [72] observed a slightly larger range of 3-7 mm day −1 during their experiment over Karnal, India for the growing seasons of 1996 and 1997, while Gu et al [73] provided an estimate between 2-4 mm day −1 for the whole maize season of 2008 in the Zhangye Oasis of China. While providing a broad range of crop water estimates for maize under a range of growing conditions, these literature values are consistent with those reported in Figures 6-8.…”

Section: Potential Of Crop Water Use Estimates From Cubesats For Precmentioning

confidence: 90%

CubeSats Enable High Spatiotemporal Retrievals of Crop-Water Use for Precision Agriculture

Aragon

Houborg

et al. 2018

Remote Sensing

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Remote sensing based estimation of evapotranspiration (ET) provides a direct accounting of the crop water use. However, the use of satellite data has generally required that a compromise between spatial and temporal resolution is made, i.e., one could obtain low spatial resolution data regularly, or high spatial resolution occasionally. As a consequence, this spatiotemporal trade-off has tended to limit the impact of remote sensing for precision agricultural applications. With the recent emergence of constellations of small CubeSat-based satellite systems, these constraints are rapidly being removed, such that daily 3 m resolution optical data are now a reality for earth observation. Such advances provide an opportunity to develop new earth system monitoring and assessment tools. In this manuscript we evaluate the capacity of CubeSats to advance the estimation of ET via application of the Priestley-Taylor Jet Propulsion Laboratory (PT-JPL) retrieval model. To take advantage of the high-spatiotemporal resolution afforded by these systems, we have integrated a CubeSat derived leaf area index as a forcing variable into PT-JPL, as well as modified key biophysical model parameters. We evaluate model performance over an irrigated farmland in Saudi Arabia using observations from an eddy covariance tower. Crop water use retrievals were also compared against measured irrigation from an in-line flow meter installed within a center-pivot system. To leverage the high spatial resolution of the CubeSat imagery, PT-JPL retrievals were integrated over the source area of the eddy covariance footprint, to allow an equivalent intercomparison. Apart from offering new precision agricultural insights into farm operations and management, the 3 m resolution ET retrievals were shown to explain 86% of the observed variability and provide a relative RMSE of 32.9% for irrigated maize, comparable to previously reported satellite-based retrievals. An observed underestimation was diagnosed as a possible misrepresentation of the local surface moisture status, highlighting the challenge of high-resolution modeling applications for precision agriculture and informing future research directions. .

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Section: Potential Of Crop Water Use Estimates From Cubesats For Precmentioning

confidence: 90%

CubeSats Enable High Spatiotemporal Retrievals of Crop-Water Use for Precision Agriculture

Aragon

Houborg

et al. 2018

Remote Sensing

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“…They also concluded that ETa depends on local meteorological elements, increasing as temperature, wind speed, and incoming solar radiation increase, and as relative air humidity decreases. Similarly, [14] concluded that ETa is positively correlated with net radiation, wind velocity, air temperature, and specific humidity. Our results show that water restriction only applied in calculating ETo, and not ETa.…”

Section: Eta (C)mentioning

confidence: 95%

Irrigation Requirement for Eucalyptus pellita during Initial Growth

Aprialdi

Haiban²,

Kløve

et al. 2019

Water

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The growth of Eucalyptus pellita in forestry plantations requires attention to water requirements, especially in the initial growth phase from seedling to field-ready plant. In this study, actual evapotranspiration (ETa), crop coefficient (Kc), and the irrigation requirement of E. pellita were assessed during the nursery growth phase (day 40–142). The experimental set-up included lysimeters with different treatments in terms of plants, drainage, and soil conditions. Plant growth and water balance were monitored during June September 2018 in an open nursery area in Riau, Indonesia. ETa was determined by the water balance lysimeter method and potential (reference) evapotranspiration (ETo) was extracted based on the Penman-Monteith method (FAO/56). The results showed that the average Kc value for E. pellita at age 40–142 days is 0.79, which exceeds that reported for E. grandis. The recommended irrigation requirement varies depending on precipitation, from 70 mL/plant/day with no rainfall to zero at precipitation of >30 mm/day. This is the first study to assess water use in E. pellita growing in pots during the nursery phase, which provides guidance on irrigation requirements during their initial growth phase.

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“…We validated the ETa estimates from the model using the latent heat flux data, and the soil water content model using the soil water content measurements collected at the site. The flux tower ETa is calculated with the following equation from Gu et al (2017):…”

Section: Model Updatesmentioning

confidence: 99%

Towards an operational irrigation management system for Sweden with a water-food-energy nexus perspective

Campana¹,

Lastanao²,

Zainali³

et al. 2021

Preprint

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The 2018 drought in Sweden has triggered questions about climate adaptation and mitigation measures, especially in the agricultural sector, which suffered the most. This study applies a water-food-energy nexus modelling framework to evaluate drought impacts on irrigation and agriculture in Sweden using 2018 and 2019 as case studies. A previous water-food-energy nexus model was updated to facilitate an investigation of the benefits of data-driven irrigation scheduling as compared to existing irrigation guidelines. Moreover, the benefits of assimilating earth observation data in the crop model have been explored. The assimilation of leaf area index data from the Copernicus Global Land Service significantly improve the crop yield estimation as compared to default crop model parameters. The results show that the irrigation water productivities of the proposed model are measurably improved compared to conventional irrigation guidelines both in 2018 and in 2019. This is mostly due to the advantage of the proposed model in providing ETc-driven guidelines by using spatially-explicit data generated by mesoscale models from the Swedish Meteorological and Hydrological Institute. During a normal year, the proposed irrigation management system leads to significant water savings as compared to conventional irrigation guidelines. The modelling results show that temperature stress during the 2018 drought played a key role in the crop yield reduction, with yield reductions of up to 35%. In the context of the water-food-energy nexus, this motivates the implementation of new technologies to reduce water and temperature stress to mitigate likely negative effects of climate change. A visualization platform is developed using an open-source package for Google Earth® to help farmers and water and energy management agencies to better understand the connections between water and energy use and food production. This can be significant, especially during the occurrence of extreme events, but also to adapt to the negative effects of climate changes.

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Actual and Reference Evapotranspiration in a Cornfield in the Zhangye Oasis, Northwestern China

Cited by 13 publications

References 52 publications

CubeSats Enable High Spatiotemporal Retrievals of Crop-Water Use for Precision Agriculture

CubeSats Enable High Spatiotemporal Retrievals of Crop-Water Use for Precision Agriculture

Irrigation Requirement for Eucalyptus pellita during Initial Growth

Towards an operational irrigation management system for Sweden with a water-food-energy nexus perspective

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