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| 2. |
- Aboulila, Tarek Selim, et al.
(författare)
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Simulation of soil water and salinity distribution under surface drip irrigation
- 2013
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Ingår i: Irrigation and Drainage. - : Wiley. - 1531-0361 .- 1531-0353. ; 62:3, s. 352-362
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Tidskriftsartikel (refereegranskat)abstract
- Higher crop production and higher water use efficiency are usually achieved simultaneously with surface drip irrigation compared to other surface irrigation methods. With increasing competition for fresh water nowadays, there is also a need for greater use of brackish water in agriculture. Effects of soil hydraulic properties, initial soil moisture content ( ), and the irrigation regime on soil water and salinity distribution under surface drip irrigation (DI) with brackish irrigation water for growing tomato in saline soil were investigated using HYDRUS-2D/3D model. Simulation scenarios were conducted including three soil types (sand, loamy sand, and sandy loam), two irrigation regimes (daily and on alternate-day irrigation), and two values. Simulation results revealed that the effect of the irrigation regime on the wetting patterns differed according to the soil’s hydraulic properties while the effect of the initial soil moisture content vanished after a few days. Alternate-day regime is suitable for fine-texture soil. Soil salinity patterns showed that the irrigation regime and value did not show any significant effect on soil salinity distribution under drip irrigation with brackish water. Higher soil salinity values occurred along the soil surface by the end of the simulation period. These higher values were closer to the emitter in sand as compared to loamy sand and sandy loam. Water balance calculations showed that as the initial soil moisture content increased, the free drainage component increased. However, the irrigation regime and initial soil moisture content value did not affect the evaporation rate and root water uptake rate.
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| 3. |
- Ghahari, Gholamreza, et al.
(författare)
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Spate irrigation of barley through floodwater harvesting in the Gareh-Bygone Plain, Iran
- 2014
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Ingår i: Irrigation and Drainage. - : Wiley. - 1531-0361 .- 1531-0353. ; 63:5, s. 599-611
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Utilizing passive floodwater for spate irrigation in arid areas is an opportunity to use marginal water for production of crops. These techniques have only partially been studied in an extensive way. This paper describes a floodwater harvesting and spreading system for spate irrigation and field experiments for cultivation of barley. The field experiments were carried out during a three-year period. The area is noteworthy for its erratic and scarce rainfall. Due to the scarce and late rainfall, only in the second year experiment barley yield was achieved. On December 5, 2009, barley was planted in one trial plot and subsequently received spate irrigation on December 8. On December 16, 2009, barley was planted in a second trial plot and in a control plot outside the system. During the growth period, the second trial plot and the control plot only received moisture from rainfall. The total weight of barley seed and straw in the trial plots was about 1616 and 2052 kg ha-1, respectively. The total weight of barley seed and straw in the control plot, however, was only about 821 kg ha-1. The results consequently displayed a significant increase in yield for the trial plots as compared with the control plot.
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| 4. |
- Mineo, C., et al.
(författare)
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On the reliability of gamma distributed dsds for modelling kinetic energy of rainfall(dagger)
- 2020
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Ingår i: Irrigation and Drainage. - : WILEY. - 1531-0353 .- 1531-0361. ; 69:5, s. 1176-1191
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Tidskriftsartikel (refereegranskat)abstract
- To retrieve the gamma drop size distribution (DSD) parameters from observed drop spectra, the most common approach is the method of moments (MM). However, the goodness of this method is still disputed. To assess its reliability, the aims of this paper are: (i) estimation of empirical values of rainfall rate (I) and kinetic energy (KE) from DSD measurements collected by a laser-optical disdrometer; (ii) estimation of gamma DSD parameters by MM and another widespread method, i.e. maximum likelihood (ML); (iii) evaluation of theoretical values of rainfall rate and KE and comparison between these values and measured ones. The novelty of this work is the assessment of both MM and ML using the rainfall intensity measured by the disdrometer as a benchmark, rather than the KE or a statistical test as done in common practice. The assessment of the goodness of the estimates was performed on variables most investigated in soil erosion studies (i.e.Iand KE). Results show that smaller error values are associated with ML and that MM does not provide reliable estimations ofI.On the other hand, both methods substantially underestimate KE with increasing rainfall intensity. (c) 2020 John Wiley & Sons, Ltd.
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| 5. |
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| 6. |
- Molle, Francois, et al.
(författare)
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VILLAINS OR HEROES? FARMERS ADJUSTMENTS TO WATER SCARCITY
- 2010
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Ingår i: IRRIGATION AND DRAINAGE. - : John Wiley and Sons, Ltd. - 1531-0353. ; 59:4, s. 419-431
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Tidskriftsartikel (refereegranskat)abstract
- Although farmers are often seen as wasting water and getting a disproportionate share of water. irrigation is losing out in the competition for water with other sectors. In cases of drought. water restrictions are overwhelmingly imposed on irrigation while other activities and domestic supply are only affected in cases of very severe shortage All over the world, farmers have been responding to the challenge posed by both short- and long-term declining water allocations in many creative ways, but these responses have often been overlooked by policy makers. This paper examines how farmers have adapted to water scarcity in six different river basins of Asia and the Middle East. It inventories the different types of adjustments observed and shows not only their effectiveness in offsetting the drop in supply but also their costs to farmers and to the environment and their contribution to basin closure. The conclusion calls for a better recognition of the efforts made by the irrigation sector to respond to water challenges and of its implications in terms of reduced scope for efficiency gains in the Irrigation sector.
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| 7. |
- Selim, Tarek, et al.
(författare)
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Evaluation of Different Irrigation Treatments with Saline Water in a Future Climate in Tunisia
- 2019
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Ingår i: Irrigation and Drainage. - : Wiley. - 1531-0353. ; 68:2, s. 281-296
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Tidskriftsartikel (refereegranskat)abstract
- Water scarcity and salinization of arable land in Tunisia are forcing the largest water user, the irrigation sector, to modernize and increase its efficiency. This study evaluated the impact of deficit irrigation with saline water in a sandy loam soil cultivated with potatoes in northern Tunisia. The evaluation considered soil salinization and irrigation water productivity in a changing climate by feeding a calibrated model in HYDRUS-2D/3D with season-long weather scenarios from one current and two future climate periods. Future weather scenarios were produced by statistically downscaling results from a regional climate model run with two greenhouse gas emission scenarios (RCP2.6 and RCP8.5). Results showed an increase in salt accumulation over the growing season and a potential decrease in crop yield for RCP8.5. RCP2.6 did not, however, result in any significant changes in salt accumulation or crop yield. Even with saline irrigation water, the use of drip technology resulted in a general leaching of salts from the root zone. This was slightly less apparent during deficit irrigation. However, irrigation water productivity was still higher during deficit irrigation than during full irrigation. Deficit irrigation could thus be profitable but long-term effects should be addressed before making final recommendations.
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