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1.
This article suggests and defines a characterisation of irrigation canal regulation methods, based on four criteria: considered variables (controlled, measured, and control action variables), logic of control, design method (structure and technique) and field implementation (configuration and device). Depending on the chosen criterion and partition rule, different classifications can be built from this characterisation. In conclusion, a structured characterisation table of the main published canal regulation methods is presented.Abbreviations ASCE American Society of Civil Engineers - CACG Compagnie d'Aménagement des Coteaux de Gascogne - CARA Compagnie d'Aménagement Rural d'Aquitaine - CARDD Canal Automation for Rapid Demand Deliveries - CEMAGREF Centre National du Machinisme Agricole, du Génie Rural, des Eaux et des Forêts - CNABRL Compagnie Nationale d'Aménagement du Bas — Rhône Languedoc - ELFLO Electronic Filter and Level Offset - FB Feedback or closed — loop control - FB dn Feedback or closed-loop downstream control - FB mi Feedback or closed-loop mixed control - FB up Feedback or closed-loop upstream control - FF Feedforward or open-loop control - GPC Generalised Predictive Control - LQR Linear Quadratic Regulator - MIMO Multiple Inputs, Multiple Outputs - nI mO n Inputs, m Outputs - P Perturbation - P Estimation of perturbations - PID Proportional, Integral, Derivative Controller - PIR Contrôleur Proportionnel, Intégral, Retard (PI Delay controller) - Q Discharge in the canal - Q dn Downstream discharge in the canal - Q in Intermediate discharge in the canal - Q up Upstream discharge in the canal - SCP Société du Canal de Provence - SISO Single Input, Single Output - U Control action variable - V Volume in a canal pool - V Elementary control action variable - w Regulator gate opening - Y Controlled variable - Y c Target controlled variable - y Water elevation - y dn Downstream water elevation of the pool (therefore upstream of a regulator) - y in Intermediate water elevation in the pool - y up Upstream water elevation of the pool (therefore downstream of a regulator) - Z Measured variable  相似文献   

2.
A two-dimensional finite element model of solute transport in a tile — drained soil — aquifer system has been applied to study the effects of the depth of impervious layer and quality of irrigation water on salt distribution during drainage of an initially highly saline soil. The model assumes steady state water movement through partially saturated soil and to drains in the saturated zone. The exact in time numerical solution yields explicit expressions for concentration field at any future time without having to compute concentrations at intermediate times. The model facilitates predictions of long-term effects of different irrigation and drainage practices on concentration of drainage effluent and salt distribution in the soil and groundwater. The model results indicated that the depth of impervious layer from drain level, dI, does not significantly influence the salt distribution in the surface 1 m root zone of different drain spacings (drain spacing (2S)=25, 50, 75 m; drain depth (dd)=1.8 m), its effect in the aquifer becomes dominant as drain spacing increases. It was also observed that dI significantly governs the quality of drainage effluent. The salinity of drainage water increases with increasing dI in all drain spacings and this effect magnifies with time. The model was also applied to study the effects of salinity of irrigation water in four drain spacing-drain depth combinations: (2S=48 m, dd=1.0 m; 2S=67 m, dd=1.5 m; 2S=77 m, dd=2.0 m; 2S=85 m, dd=2.5 m). The results indicated that a favorable salt balance can be maintained in the root zone even while irrigating with water up to 5 dS/m salinity in drains installed at 48 to 67 m spacing and 1.0 to 1.5 m depth. Further, irrespective of the quality of irrigation water, the deep, widely spaced drains (dd=2.5 m, 2S=85 m) produced much saline drainage effluent during the initial few years of operation of the drainage system than the more shallow, closely spaced drains, thus posing a more serious effluent disposal problem.
Résumé Considérant les conséquences potentiellement sérieuses de la pollution du sol et de l'eau souterraine dans l'agriculture irriguée, il est devenu absolument nécessaire de développer des modèles de simulation en vue d'évaluer les effects à long terme des méthodes agricoles modernes. Un modèle d'éléments finis à deux dimensions du transport en solution dans un système de sol aquifère drainé au moyen de tuyaux a été développé et validé sur le terrain (Kamra et al. 1991 a, b). Le modèle assume le mouvement de l'eau à régime constant à travers un sol partiellement saturé et jusqu'aux drains dans la zone saturée. La solution numérique exacte dans le temps produit des expressions explicites pour le champ de concentration à un temps future quelconque sans avoir à calculer les concentrations aux temps intermédiares. Le modèle facilite les prédictions des effets à long terme des diverses méthodes d'irrigation et de drainage sur la concentration des effluents de drainage et sur la distribution de la salinité dans le sol et dans l'eau souterraine. Les résultats du modèle relatifs aux effets de la profondeur de la couche imperméable et de la qualité de l'eau d'irrigation sur la distribution de la salinité lors du drainage d'un sol fortement salé à l'origine sont mentionnés dans la présente communication.Les résultats du modéle ont indiqué que la profondeur de la couche imperméable depuis le niveau du drain, dI, n'influence pas d'une façon significative la distribution de la salinité dans la zone superficielle radiculaire de 1 m des divers écartements de drains (écartement de drains, 2S=25, 50, 75 m; profondeur des drains, dd=1.8 m); son effet dans l'aquifère devient dominant à mesure que l'écartement de drains augmente. On a aussi constaté que le niveau du drain dI influence d'une manière significative les effluents du drainage. La salinité de l'eau de drainage augmente à mesure que dI augmente dans tous les écartements de drains et cet effet s'amplifie avec le temps. Le modèle a été aussi appliqué pour étudier les effets de la salinité de l'eau d'irrigation dans le cas de quatre conbinaisons d'écartement de drain et de profondeur de drain: (2S=48 m, dd=1,0 m; 2S=67 m, dd=1,5 m; 2S=77 m, dd=2,0 m; 2S=85 m, dd=2,5 m). Les résultats ont indiqué qu'un bilan de salinité favorable peut être maintenu dans la zone radiculaire même en irrigant avec de l'eau d'une salinité de 5 dS/m dans des drains installés à un écartement de 48 à 67 m et une profondeur de 1,0 à 1,5 m. De plus, indépendamment de la qualité de l'eau d'irrigation les drains profonds à grand écartement (dd=2,5 m, 2S=85 m) produisaient une grande quantité d'effluents salés de drainage durant les quelques premières années de l'exploitation du système de drainage par rapport aux drains peu profonds à écartement serré, posant ainsi un problème plus sérieux d'évacuation des effluents.Les résultats du développement et de l'évaluation du modèle on montré qu'il peut être utilement employé en vue d'une évaluation judicieuse de la variation de temps escomptée dans la salinité des effluents de drainage lors de la mise en valeur des sols salins et peut ainsi aider à formuler son règlement plus sûr du point de vue environnement et les projects d'évacuation.
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3.
The simulation model SIDRA is based on a semi-analytical and semi-numerical solution to the Boussinesq equation. It has been developed on the ground of theoretical and field experimental results with the aim of a good prediction of both drainage peak and recession flow rates. Theoretical aspects and basic equations of the model are presented for the most general case where both soil physical properties and water table shapes are depth-dependent. The parameter sensitivity and field performances of the model are estimated in shallow loamy soils facing a seasonal waterlogging during winter season in France. Water table shape factors are the most sensitive parameters. Drainable porosity is slightly more sensitive than hydraulic conductivity for drainflow rate prediction whereas hydraulic conductivity is slightly more sensitive for water table elevation prediction. A comparison of experimental and simulated long term discharge and water table exceedance duration curves shows that the model could be a useful tool to assess the performances and control the relevance of a given subsurface drainage design.
Résumé Le modèle de simulation SIDRA est basé sur une résolution semi-analytique et semi-numérique de l'équation de Boussinesq. Il a été développé à partir d'une approche théorique et de l'analyse de résultats d'expérimentations de terrain avec pour principal objectif d'atteindre une bonne prédiction des débits de pointe et de tarissement. Les principales équations du modèles sont présentées dans leur forme la plus générale qui permet de prendre en compte des propriétés hydrodynamiques et des formes de nappe dépendantes de la profondeur. L'étude de sensibilité aux paramètres et l'évaluation des performances du modèle sont réalisées dans le cas de sols limoneux peu profonds, sur la période hivernale où se manifeste l'engorgement des sols en France. Le modèle est très sensible aux variations des facteurs de forme de nappe. Concernant les paramètres hydrodynamiques, les débits simulés sont plus sensibles aux variations de la porosité de drainage qu'à celles de la conductivité hydraulique. A l'inverse les hauteurs de nappe simulées sont plus sensibles aux variations de conductivité hydraulique. Une comparaison sur une longue période des fréquences de dépassement de débits et hauteurs de nappe, simulées et observées, montre que le modèle peut constituer un bon outil de contrôle de l'efficacité d'un réseau de drainage et de son dimensionnement.
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4.
Modeling flow and transport in heterogeneous,dual-porosity drained soils   总被引：6，自引：0，他引：6  
A finite element solution of the equations for coupled flow of water and transport of chemicals in slowly permeable soils containing macropores is presented. Two example solutions are presented for the condition of a horizontal soil profile with a drainage ditch. The first is for steady state saturated flow while the second is for transient water flow produced by time varying rainfall. Through these examples it is found that the characteristic leaching time of a chemical from the soil matrix is determined by the rate of transfer of chemical mass between the pore domains. When the rate of transfer is zero, the rate of leaching is greatly retarded compared to the case where the rate of transfer is nonzero. The chemical outflow from the macropore domain is very rapid when the rate of transfer is zero, while the chemical outflow is greatly delayed, but increased in magnitude when the rate of chemical transfer is nonzero.
Résumé Une solution par éléments finis des équations régissant lécoulement de l'eau et son influence sur le transport des composés chimiques à l'intérieur de sols à perméabilité lente contenant des macropores est présentée.Deux solutions sont citées en exemple, traitant le cas d'un sol sans pente avec un fossé d'évacuation.La première solution est pour un écoulement saturé en régime permanent alors que la seconde traite de l'écoulement variable résultant de pluies d'intensités changeantes.Ces exemples ont permis de déterminer que le temps caractéristique nécessaire à la désorption d'un composé chimique donné de la matrice du sol est fonction du taux de transfert de ce composé entre les domaines de macropores.Lorsque le taux de transfert est nul, le taux de désorption est considérablement ralenti par rapport aux cas où le taux de transfert n'est pas nul.Le composé chimique s'évacue très rapidement des domaines des macropores lorsque le taux de transfert est nul, alors que l'évacuation est considérablement retardée mais beaucoup plus volumineuse lorsque le taux de transfert du composé chimique n'est pas nul.
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5.
In FRANCE, for about twenty years now, water control has been achieved in canals specially designed for optimum efficiency in water conveyance and distribution. The regulation techniques consist in particular in using downstream or upstream float gates and baffle distributors — often used in Morocco for example. Their use implies specially designed canals with adapted civil engineering works and dykes. The application of these regulation techniques on old canals with continuous flow very often implies heavy investment and is impossible on natural rivers. On the other hand, the development of micro-computers and data transmission networks, and the definition of mathematical methods dealing with control systems, have pointed the way to another approach to the problem set by improving the efficiency of the feeder canal control. Using these new techniques, the Compagnie d'Aménagement des Coteaux de Gascogne (CACG), in collaboration with a staff of researchers, has studied a new approach to water management, and since 1984 has produced a complete set of automatic control equipment allowing the irrigation of 4000 ha, with a system efficiency close to 0.9. This approach has been set up in particularly difficult conditions, the river being used to supply several irrigated perimeters. It could as easily be installed on a canal, where it is not economical to invest in the large hydraulic structures necessary for traditional control.; The economic stakes are important because it is a matter of improving the performance of existing structures with little specific investment (sensors, micro-computers, software) and with extensive improvement in the systems management.  相似文献   

6.
不同灌溉方式对制种玉米产量及水分利用效率的影响   总被引：1，自引：0，他引：1  
通过田间试验,研究了畦灌、常规沟灌、隔沟交替灌3种灌溉方式对制种玉米产量及水分利用效率的影响,结果表明,不同灌溉方式下,制种玉米产量为8.73~10.87 t/hm~2,耗水量为349.7~625.0 mm,WUE为1.40~3.01kg/m~3。隔沟交替灌溉方式耗水量最低,畦灌方式最高,常规沟灌居中。相同灌溉定额条件下,隔沟交替灌制种玉米产量较常规沟灌增减幅度在-2.43%~10.24%。常规沟灌方式若能保证作物需水关键期的灌溉,适度减少灌水不会造成制种玉米减产。产量构成要素结果表明,行粒数、出籽率、穗长、穗粗、秃尖长、千粒重产量构成要素对产量的累积贡献率达85.54%。在甘肃河西地区,制种玉米全生育期灌水8次(苗期1次,拔节期2次,抽穗期1次,灌浆期2次,乳熟期2次),灌溉定额2 250 m~3/hm~2的隔沟交替灌溉方式(T6处理)能稳定提高产量和水分利用效率。  相似文献   

7.
不同灌水方式下春玉米的根系生长分布   总被引：2，自引：0，他引：2  
为了研究不同灌水方式对春玉米根系分布的影响,在大田条件下对玉米进行垄植沟灌,设计常规沟灌（CI）、交替隔沟灌溉（AI）和固定隔沟灌溉（FI）3种灌水方式.结果表明,（0,40]cm土层中,根长密度以AI较大,FI较小;（60,100]cm土层中,CI下根长密度较小;FI下的植株两侧根长密度差异明显,CI和AI与之相反.（0,100]cm土层中,监测时期内,AI下的玉米总根长和总根干质量都较大.相较FI,AI下的籽粒产量、生物产量和灌溉水利用率分别提高17.37%,18.42%和17.45%.CI表现介于AI与FI之间.抽雄期、植株两侧和（0,40]cm土层根系生长分布受土壤含水率影响较大.可见,局部灌溉对深层根系生长有利,抽雄期植株两侧（0,40]cm土层根系生长分布受灌水方式影响最大;CI与AI下的根系分布相对均匀;与FI和CI相比,AI方式既能促进根系生长,也有利于产量和灌溉水利用率的提高.  相似文献   

8.
Canopy temperature measurements with infrared thermometry have been extensively studied as a means of assessing plant water status for field and row crops but not for fruit trees such as peaches. Like in many regions of the world, the lack of water is beginning to impact production of tree fruit such as peaches in the San Joaquin Valley of California. This is an area where irrigation is the only source of water for agricultural crops in the summer growing season. A two-year field study was conducted to assess plant water stress using infrared canopy temperature measurements and to examine its feasibility for managing postharvest deficit irrigation of peach trees. Twelve infrared temperature sensors were installed in a mature peach orchard which received four irrigation treatments: furrow and subsurface drip irrigation with or without postharvest water stress. During the two-year period, measured midday canopy to air temperature differences in the water-stressed postharvest deficit irrigation treatments were in the 5-7 °C range, which were consistently higher than the 1.4-2 °C range found in the non-water-stressed control treatments. A reasonable correlation (R2 = 0.67-0.70) was obtained between stem water potential and the canopy to air temperature difference, indicating the possibility of using the canopy temperature to trigger irrigation events. Crop water stress index (CWSI) was estimated and consistently higher CWSI values were found in the deficit irrigation than in the control treatments. Results of yield and fruit quality assessments were consistent with the literature when deficit irrigation was deployed.  相似文献   

9.
Root distribution of field grown potatoes (cv. Folva) was studied in 4.32 m2 lysimeters and subjected to full (FI), deficit (DI), and partial root-zone drying (PRD) irrigation strategies. Drip irrigation was applied for all irrigations. Irrigations were run in three different soils: coarse sand, loamy sand, and sandy loam. Irrigation treatments started after tuber bulking and lasted until final harvest with PRD and DI receiving 65% of FI. Potatoes irrigated with water-saving irrigation techniques (PRD and DI) did not show statistically different dry root mass and root length density (RLD, cm root per cm3 soil) compared with root development in fully irrigated (FI) potatoes. Highest RLD existed in the top 30-40 cm of the ridge below which it decreased sharply. The RLD was distributed homogenously along the ridge and furrow but heterogeneously across the ridge and furrow with highest root density in the furrow. Most roots accumulated in the surface layers of coarse sand as compared to the other soil types. In the deep soil profile (30-70 cm) a higher root density was found in loamy sand compared with the sandy loam and coarse sand. Approximately twice the amounts of roots were found below the furrows compared with the corresponding layers below the ridges. The RLD values in the soil profile of the ridges and the furrows followed the Gerwitz and Page model: RLD = α × exp(−β × z). The highest value of surface root density (α) and rate of change in density (β) was found in coarse sand while the lowest values of α and β were found in the sandy loam and loamy sand. The model estimated the effective rooting depth in coarse sand and sandy loam quite well but did slightly overestimate it in the loamy sand. Statistical analysis showed that one α and β value can be used for each soil irrespective of the irrigation treatment. Thus, the effective rooting depths corresponding to root length densities of 0.1 and 0.25 cm cm−3 for sandy loam, loamy sand, and coarse sand soils were 99, 141, and 94 cm, and 80, 115, and 78 cm, respectively, calculated from top of the ridge. The findings of this study can be used in practice for efficient use of water and nutrients in the field.  相似文献   

10.
A field experiment was conducted for 2 years to investigate the effects of deficit irrigation, nitrogen and plant growth minerals on seed cotton yield, water productivity and yield response factor. The treatment comprises six levels of deficit irrigation (Etc 1.0, 0.9, 0.8, 0.7, 0.6 and 0.5) and four levels of nitrogen (80, 120, 160 and 200 kg N ha−1). These were treatments superimposed with and without plant growth mineral spray. Furrow irrigation treatments were also kept. Cotton variety Ankur-651 Bt was grown during 2006 and 2007 cotton season. Drip irrigation at 1.0 Etc saved 26.9% water and produced 43.1% higher seed cotton yield over conventional furrow irrigation (1.0 Etc). Imposing irrigation deficit of 0.8 Etc caused significant reduction in seed cotton yield to the tune of 9.3% of the maximum yield. Further increase in deficit irrigation from 0.7 Etc to 0.5 Etc significantly decreased seed cotton yield over its subsequent higher irrigation level. Decline in the yield under deficit irrigation was associated with reduction in number of bolls plant−1 and boll weight. Nitrogen at 200 kg ha−1 significantly increased mean seed cotton yield by 36.3% over 80 kg N ha−1. Seed cotton yield tended to increase linearly up to 200 kg N ha−1 with drip Etc 0.8 to drip Etc 1.0. With drip Etc 0.6-0.5, N up to 160 kg ha−1 provided the highest yield, thereafter it had declined. Foliar spray of plant growth mineral (PGM) brought about significant improvement in seed cotton yield by 14.1% over control. The water productivity ranged from 0.331 to 0.491 kg m−3 at different irrigation and N levels. On pooled basis, crop yield response factor of 0.87 was calculated at 20% irrigation deficit.  相似文献   

11.
The factor limiting the increase in winter wheat yield was not the deficiency of light radiation but the low radiation use efficiency (RUE). In 2004-2005 and 2005-2006, an experiment was conducted at the Agronomy Station of Shandong Agricultural University to study the effects of irrigation and different planting patterns on the photosynthetic active radiation (PAR) capture ratio, PAR utilization, and winter wheat yield. In this experiment, winter wheat was planted in four patterns as follows: uniform row planting (U; row spacing, 30 cm), “20 + 40” wide-narrow row planting (W), “20 + 40” furrow planting (F), and “20 + 40” bed planting (B), which are very popular in North China. The results showed that under different irrigation regimes, there was no significant difference (less than 15.93%) between any of the planting patterns with respect to the amount of PAR intercepted by the winter wheat canopies. However, significant differences were observed between different planting patterns with respect to the amount of PAR intercepted by plants that were 60-80 cm above the ground surface (53.35-225.16%). This result was mainly due to the changes in the vertical distributions of leaf area index (LAI). As a result, the effects of the planting patterns on RUE and the winter wheat yield were due the vertical distribution of PAR in the winter wheat canopies. During the late winter wheat growing season, irrespective of the applied irrigation, the RUE in case of F was higher than that in case of U, W, and B by 0.05-0.09, 0.04-0.08, and 0.02-0.12 g/mol, respectively, and the yield was higher by 238.39-693.46, 160.02-685.96, and 308.98-699.06 kg/ha, respectively. Only under the fully irrigated conditions, the RUE and winter wheat yield significantly (LSD; P < 0.05) increased in case of B. This experiment showed that in North China, where the water shortage is the highest, application of planting pattern B should be restricted. Instead, F should be used in combination with deficit irrigation to increase the RUE and grain yield of winter wheat.  相似文献   

12.
Water for irrigation is in short supply worldwide, therefore reduced irrigation options will have to be explored. We did this for ‘Golden Smoothee’ apple over the growing seasons of 2003-2005 at the IRTA-Estaciò Experimental de Lleida (41°37′ N; 0° 52′ E; 260 m a.s.l.), Catalonia, Spain. This region has a temperate climate with winter-dominant rainfall. Averages of annual rainfall and reference evapotranspiration over 2000-2009 were, respectively, 371 and 1023 mm. The treatments were: Control (C), receiving full irrigation; spring irrigation (SI), where at the budbreak 80 mm of water was applied followed by watering so that the total water applied in the season was either at 33% of C (SI-33) or at 50% of C (SI-50); and deficit irrigation (DI), where trees were irrigated either with 33% of C (DI-33) or with 50% of C (DI-50). Water in DI was applied either through one dripper per tree (DI-33-1d and DI-50-1d) or through two drippers per tree (DI-33-2d and DI-50-2d). Trees showed biennial bearing with 2004 being an ‘off-year’ when treatment effects on yield were largely masked by the higher values of stem water potential associated with lower crop loads. SI-50 and SI-33 performed poorly and cannot be recommended. For each of the DI treatments, the one-dripper version increased fresh market yield and fruit size. For example, although DI-50 performed better than DI-33, DI-33-1d was similar in performance to DI-50-2d. Under water shortage, we recommend whole-season application of DI-50-1d and DI-33-1d depending on the availability of water supply.  相似文献   

13.
结合中水绿地灌溉对植物影响的研究,采用美国国家科学院(NAS)提出的四步评价法,对深圳罗芳污水治理厂生产的中水水质中有害的化学物质和致病微生物检测结果进行了评价。结果表明,中水水质中的化学致癌物质(铬、砷、镉)、化学非致癌物质(铅、镍、氰化物、氟化物、氨氮、挥发酚)致癌风险P分别在10-6/a、10-7/a数量级以下,分别小于国际权威机构制定的风险阈值10-5/a、10-6/a数量级;致病微生物(轮状病毒、甲肝病毒、柯萨奇病毒)致病风险P均在10-5数量级以下,小于风险阈值10-4数量级。由此表明,中水运用于城市绿地灌溉中是安全的、可行的,不会对人体的健康造成危害。  相似文献   

14.
Olive is one of the fruit tree species for which measurements of the trunk diameter variation (TDV) has shown a lower potential both for monitoring water stress and for scheduling irrigation. This is particularly true in the case of old, big olive trees with heavy fruit load. Fernández et al. (2011, J. Environ. Exp. Bot. 72, 330-338) observed that the daily difference for maximum trunk diameter between deficit irrigated ‘Manzanilla’ olive trees and control trees growing under non-limiting soil water conditions, termed DMXTD, is more sensitive and reliable for detecting the water stress of the trees than other widely used TDV-derived indices. However, they considered their results as preliminary because of the lack of replications. The aim of this work was to evaluate the usefulness of the DMXTD index for detecting plant water stress in an orchard with 12-year-old ‘Arbequina’ olive trees with heavy fruit load. The performance of DMXTD for detecting water stress of the trees was compared to that of the signal intensity for the maximum daily shrinkage (SI-MDS) derived from the same TDV records. Results showed that SI-MDS was not useful for indicating the water stress of the trees. On the other hand, the dynamics of DMXTD mimicked those of the soil and plant water status. Four instrumented trees per treatment (replicates) were enough to reduce the uncertainty of the TDV measurements to a reasonable level. Our results show that DMXTD is a useful index to detect the onset, and severity, of water stress in mature ‘Arbequina’ olive trees with heavy fruit load. They also suggest a potential of DMXTD for scheduling low frequency deficit irrigation strategies.  相似文献   

15.
The evapotranspiration of hedge-pruned olive orchards (Olea europaea L. cv. Arbequina) was measured under the semiarid conditions of the middle Ebro River Valley in a commercial olive orchard (57 ha) during 2004 and 2005. No measured ETc values for this type of olive orchards have previously been reported. An eddy covariance system (krypton hygrometer KH20 and 3D sonic anemometer CSAT3, Campbell Scientific) was used. The eddy covariance measurements showed a lack of the energy balance closure (average imbalance of 26%). Then sensible and latent heat (LE) flux values were corrected using the approach proposed by Twine et al. (2000) in order to get daily measured olive evapotranspiration (ETc) and crop coefficient (Kc) values. The highest measured monthly ETc averages were about 3.1-3.3 mm day−1, while the total seasonal ETc during the irrigation period (March-October) was about 585 mm (in 2004) and 597 mm (in 2005). Monthly Kc values varied from about 1.0 (Winter) to 0.4-0.5 (Spring and Summer). These Kc values were similar to Kc values reported for round-shape canopy olive orchards, adjusted for ground cover, particularly during late Spring and Summer months when differences among measured and published Kc values were about less than 0.1.  相似文献   

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