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Agricultural Water Management
Elsevier
Agricultural Water Management

Elsevier

0378-3774

Agricultural Water Management/Journal Agricultural Water ManagementSCIISTPEI
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    A novel evapotranspiration based irrigation quantification method using the hydrological similar pixels algorithm

    Pelgrum H.Silva I.R.D.O.Brombacher J.Degen J....
    15页
    查看更多>>摘要：? 2022 The AuthorsGlobally, the agricultural sector is the largest consumer of fresh water, despite the increased efficiency in irrigation. Remote sensing is a valuable tool to monitor agricultural water use. In this study, we demonstrate a novel algorithm that computes high-resolution (10 m) remote sensing-based evapotranspiration (ET) data linked exclusively to irrigation, i.e. the incremental evapotranspiration (ETincr). The methodology compares the ET of irrigated agricultural pixels to the weighted average ET of a subset of natural Hydrological Similar Pixels (HSP). The hydrological similarity is based upon a set of features derived from DEM, soil texture, reference evapotranspiration, and precipitation datasets. The difference in ET between the subset of hydrological similar natural pixels and the corresponding irrigated agricultural pixel is explanatory for the amount of ET related to irrigation (ETincr). These results are then converted to the water use (m3) per agricultural field. The method is validated for three study areas in South Africa, Spain, and Australia. Comparing the monthly and seasonal water use estimates to water meter observations in the Hex Valley (South Africa), yielded an R2 of 0.751 and 0.780, respectively. For the Ebro (Spain) and Namoi (Australia) study areas, the accuracy of the monthly estimates decreased. In Australia, this was a result of the water meters being linked to local reservoirs, instead of the direct use of the irrigation systems. In total, 8 out of the 27 validation fields with monthly data showed a Kling-Gupta Efficiency (KGE) larger than 0.5, which highlights that the temporal variability can be captured well by the model. Generally, seasonal estimates showed to be most accurate, which makes the product suitable for comparison with seasonal water allocations and could help to monitor overconsumption in water-scarce environments.
      原文链接:
    • NSTL
    • Elsevier

    Effects of subsurface drip-irrigated soybean seeding rates on grain yield, evapotranspiration and water productivity under limited and full irrigation and rainfed conditions

    Irmak S.Sandhu R.
    17页
    查看更多>>摘要：? 2022 Elsevier B.V.There is lack of research, data and knowledge that can be transferable to producers, their advisors and managers in terms of dynamic relationships of soybean [Glycine max (L.) Merr.] yield, crop evapotranspiration (ETc), crop water productivity (CWP) with respect to irrigation water applied, seeding rate, and irrigation vs. ETc relationships. These dynamics were investigated relative to five seeding rates (185,250; 247,000; 308,750; 370,500 and 432,250 seeds ha?1) under full irrigation treatment (FIT), limited irrigation (75% FIT and 50% FIT), and rainfed. Rainfed treatment had the highest soil-water depletion, followed by 50% FIT, 75% FIT and FIT. No clear trend of soil-water depletion was observed due to seeding rates. In 75% FIT and FIT, highest yield was observed with 308,750 seeds ha?1 seeding rate. Yield plateaued at 4.3 tons ha?1 and no further yield increase was observed with increasing seeding rate beyond 308,750 seeds ha?1. While ETc differed significantly (p < 0.05) due to irrigation treatments and seeding rates, ETc was affected more by the irrigation levels than the seeding rates. ETc ranged from 460 mm for rainfed treatment to 489 mm for FIT under the lowest seeding rate (247,000 seeds ha?1) in 2014; and from 308 mm for rainfed under highest seeding rate (432,250 seeds ha?1) to 395 mm for FIT under 308,750 seeds ha?1 in 2015. ETc exhibited a linear response to irrigation and yield. Irrigation vs. ETc slopes indicate that for every 25.4 mm increase in irrigation application, ETc can increase between 5.8 mm and 17.3 mm, depending on the seeding rates. The highest weekly ETc of 62 mm in 2014 and 44 mm in 2015 was recorded for the same seeding rate of 308,750 seeds ha?1. IWP was highest (0.96 kg m?3) for 247,000 seeds ha?1 under 75% FIT in both seasons. The highest CWP of 0.93 kg m?3 was obtained with the 308,750 seeds ha?1 in both 75% FIT and FIT in 2014 while the highest CWP of 1.25 kg m?3 was measured for FIT under 432,250 seeds ha?1 in 2015. Further long-term research is suggested to investigate the potential differences in physiological and phenological parameters, growth, ETc, water productivity, yield, and yield response factors under different seeding rates for different soybean varieties under different irrigation levels and methods.
      原文链接:
    • NSTL
    • Elsevier

    Regional water-saving potential calculation method for paddy rice based on remote sensing

    Wei J.Cui Y.Zhou S.Luo Y....
    12页
    查看更多>>摘要：? 2022 Elsevier B.V.To improve the calculation applicability and operability of regional water-saving potential (RWSP) for paddy rice, a calculation method based on remote sensing (RWSP-RS) was proposed. RWSP-RS consists of three sections: (a) paddy rice mapping by the decision tree algorithm, (b) rice evapotranspiration (ET) inversion under different irrigation modes by the surface energy balance algorithm for land (SEBAL), and (c) WSP based on ET (WSPE) and irrigation (WSPI) calculation by coupling water balance models for paddy fields. The RWSP-RS was applied in the Zhanghe Irrigation District in southern China in 2018 and 2019. The results showed that the three sections of RWSP-RS had high precision: paddy rice mapping errors ranged from 2% to 16%; WSPE of paddy rice errors were 26 mm and 5 mm for 2018 and 2019, respectively; and WSPI errors were 5 mm and 23 mm for 2018 and 2019, respectively. The WSPI of paddy rice in the whole region was 44.52 million m3 and 99.12 million m3 for 2018 and 2019, respectively. RWSP-RS has the characteristics of solid operability, good regional applicability, and time and labor savings, making it a recommended method for calculating the RWSP of paddy rice and contributing to regional water resource management.
      原文链接:
    • NSTL
    • Elsevier