Papers by Luís Santos Pereira
el cultivo de la papaya durante los últimos años, resulta de interés el conocimiento de los eleme... more el cultivo de la papaya durante los últimos años, resulta de interés el conocimiento de los elementos técnicos y agronomicos necesarios para una adecuada programación del riego a partir de la estimación de las necesidades hidrícas del cultivo. Para esto se utilizo el modelo SIMDualKc el cual efectua el calculo de la evapotranspiración del cultivo (ET c ) y la programación del riego a partir de la metodología de los coeficientes culturales duales (K c =K cb +K e ). La investigación fue realizada en la Estación Experimental de Riego y Drenaje, situada en Alquízar, provincia La Habana, Cuba. Los experimentos fueron desarrollados entre el período marzo-noviembre 1997. Se utilizó la Papaya var. "Maradol roja". La calibración consistió en la búsqueda de los coeficientes culturales basales para las diferentes etapas de desarrollo del cultivo reduciendo al mínimo las diferencias entre los valores simulados y observados del contenido de humedad del suelo. Fue evaluada la bondad de ajuste de las predicciones del modelo, realizándose una serie de análisis estadísticos. Se puede concluir que el modelo puede ser utilizado para la generación de calendarios alternativos de riego destinados a mejorar el ahorro de agua y la productividad de la papaya en estas condiciones edafoclimáticas.
IFIP advances in information and communication technology, 2013
Win ISAREG is a model for performing soil water balance and estimating impacts of water stress on... more Win ISAREG is a model for performing soil water balance and estimating impacts of water stress on yields for crops, concentrating on the evaluation of irrigation scheduling. The soil water balance of different type of soil and crop were study in the typical semiarid Horqin Sandy land area in this paper. With the data from Agula experimental station and concentrate on site A3 with Artemisia and site D1 with leymus, the calibration and validation for both sites were performed by using field observations of 2008 and 2009, aiming to adjust the crop coefficients Kc and soil water depletion fractions for nonstress conditions p to the local conditions. Results show that the coefficients of regression was close to 1.0, the relative errors to estimate the soil water content was 0.09for Artemisia and 0.10 for leymus. Results prove the practicality and applicability of using ISAREG for the Horqin semiarid area.
Irrigation Science, Jun 18, 2023
Natural and planted grasslands play a very important role in agriculture as source of various eco... more Natural and planted grasslands play a very important role in agriculture as source of various ecosystem services, including carbon sequestration and biodiversity, and are responsible for a large fraction of agricultural water use in rainfed and irrigated fields. It is, therefore, relevant to precisely know their water use and vegetation requirements with consideration of relevant climate, from extremely cold, dry, with long winter seasons, to tropical humid and hot climates, thus with a large variability of vegetation. Semi-natural grasslands are basically used for grazing and mainly refer to highland pastures and meadows, steppes, savannas, pampas, and mixed forest systems. The FAO method to compute crop (vegetation) evapotranspiration (ET c ) through the product of a crop coefficient (K c ) by the reference evapotranspiration (ET o ) is adopted. The selected papers were those where actual ET c (ET c act ) was derived from field observations and ET o was computed with the FAO56 definition, or with another method that could be referred to the former. Field derived ET c act methods included soil water balance, Bowen ratio and eddy covariance measurements, as well as remote sensing vegetation indices or surface energy balance models, thus reviewed K c act (ET c act /ET o ) values were obtained from field data. These K c act refer to initial, mid-season and end season (K c act ini , K c act mid , K c act end ) when reported values were daily or monthly; otherwise, only average values (K c act avg ) were collected. For cases relative to cold or freezing winters, data refer to the warm season only. For grasses cut for hay, K c act ini , K c act mid , and K c act end refer to a cut cycle. K c act values rarely exceeded 1.25, thus indicating that field measurements reported did respect the available energy for evaporation. Overall, K c act mid for semi-natural grasslands in cold climates were lower than those in hot climates except when available water was high, with K c act mid for meadows and mountain pastures generally high. Steppes have K c act mid values lower than savannas. Grasses commonly planted for hay and for landscape generally showed high K c act mid values, while a larger variability was observed with grasses for grazing. The collected K c act values were used to define standard K c values for all grassland and grasses. Nevertheless, the tabulated K c act are indicative values of K c to be used for actual water management purposes and/or irrigation scheduling of planted grasslands. It is expected that a better knowledge of the standard and/or indicative K c values for a wide variety of grasslands and grasses will support better management aimed to improve grass productivity and ecosystem services, including biodiversity and carbon sequestration.
Central theme, technology for all: sharing the knowledge for development. Proceedings of the International Conference of Agricultural Engineering, XXXVII Brazilian Congress of Agricultural Engineering, International Livestock Environment Symposium - ILES VIII, Iguassu Falls City, Brazil, 31st Aug..., 2008
Water
Vineyards represent complex Mediterranean agrosystems that deliver significant ecosystem services... more Vineyards represent complex Mediterranean agrosystems that deliver significant ecosystem services to society. Yet, many vine-growers still need to assimilate the importance of crop and soil management to the conservation of soil and water resources. The main objective of this study was to evaluate water use and the water balance terms in rainfed and irrigated vineyards in Italy and Portugal, respectively, in both cases aiming at the sustainability of natural resources use. The SIMDualKc model is used for both sites after calibration and validation by fitting soil water content measurements. The Italian case study focused on the impacts of inter-row conservation management in hillslope vineyards while the Portuguese case study analyzed irrigation water management under scarcity in flat vineyards. For the Italian vineyards, the model results focused on the evapotranspiration fluxes and their partition, control of surface runoff, and soil water recharge provided by the inter-row soil m...
Agricultural Water Management, 2020
The computation of the grass reference evapotranspiration with the FAO56 Penman-Monteith equation... more The computation of the grass reference evapotranspiration with the FAO56 Penman-Monteith equation (PM-ET o) requires data on maximum and minimum air temperatures (T max , T min), actual vapour pressure (e a), shortwave solar radiation (R s), and wind speed at 2 m height (u 2). Nonetheless, related datasets are often not available, are incomplete, or have uncertain quality. To overcome these limitations, several alternatives were considered in FAO56, while many other procedures were tested and proposed in very numerous papers. The present study reviews the computational procedures relative to predicting the missing variables from temperature, i.e., the PM temperature approach (PMT), and estimating ET o with the Hargreaves-Samani (HS) equation. For the PMT approach, procedures refer to predicting: (a) the dew point temperature (T dew) from the minimum or the mean air temperature; (b) shortwave solar radiation (R s) from the air temperature difference (TD = T max-T min) combined with a calibrated radiation adjustment coefficient (k Rs); and (c) wind speed (u 2) using a default value or a regional or local average. The adequateness of computing T dew from air temperature was reassessed and the preference for using an average u 2 has been defined. To ease the estimation of R s, for the PMT approach and the coefficient of the HS equation, multiple linear regression equations for predicting k Rs were developed using local averages of the temperature difference (TD), relative humidity (RH) and wind speed as independent variables. All variables were obtained from the Mediterranean set of CLIMWAT climatic data. Two types of k Rs equations were developed: climate-focused equations specific to four climate types-humid, sub-humid, semi-arid, and hyper-arid and arid-, and a global one, applicable to any type of climate. The usability of the k Rs equations for the PMT and HS methods was assessed with independent data sets from Bolivia, Inner Mongolia, Iran, Portugal and Spain, covering a variety of climates, from hyper-arid to humid. With this purpose, ET o estimated with PMT and HS (ET o PMT and ET o HS) were compared with PM-ET o computed with full data sets to evaluate the usability of the k Rs equations. Adopting the climate-focused k Rs equations with ET o PMT , the RMSE averaged 0.59, 0.64, 0.65 and 0.72 mm d −1 for humid, sub-humid, semi-arid, and arid and hyper-arid climates, respectively, while the RMSE values relative to ET o HS when using the respective climate-focused k Rs equations averaged 0.58, 0.60, 0.60 and 0.69 mm d −1 for the same climates. These results are similar to those obtained with the k Rs global equation. The accuracy of the PMT approach when using the k Rs equations was also evaluated when one, two, or all three T dew , R s and u 2 variables are missing and the resulting goodness-of-fit indicators demonstrated the advantage of the combined use of observed and estimated weather variables. The usability of the k Rs equations for an efficient parameterization of both the PMT approach and the HS equation is demonstrated with similar performance of PMT and HS procedures for a variety of climates. Because the ET o HS results depend almost linearly on temperature, the PMT approach, using estimates of the weather variables, is able to mitigate those temperature impacts, which trends may be contrary to those of other variables that determine ET o. The clear advantage of the PMT approach is that it allows using the available weather data in combination with estimates of the missing variables, which provides for more accurate ET o computations.
Water, 2019
The authors wish to make the following corrections to this paper [...]
… 2010, held 2-7 May …, 2010
The main purpose of this work is to evaluate the most appropriate Vegetation Indices (VI) from MO... more The main purpose of this work is to evaluate the most appropriate Vegetation Indices (VI) from MODIS (250 m resolution), to identify and assess the growth pattern of semi-natural meadows in northern Portugal. Sixteen-day MODIS-TERRA (250x250m) ...
CI HEAM, 2007
Karam F. (ed.), Karaa K. (ed.), Lamaddalena N. (ed.), Bogliotti C. (ed.). Harmonization and integ... more Karam F. (ed.), Karaa K. (ed.), Lamaddalena N. (ed.), Bogliotti C. (ed.). Harmonization and integration of water saving options. Convention and promotion of water saving policies and guidelines Bari : CIHEAM / EU DG Research Options Méditerranéennes : Série B. Etudes et Recherches; n. 59 2007 pages 19-35 Article available on lin e / Article dispon ible en lign e à l'adresse :
FAO, Rome, 1998
This publication presents an updated procedure for calculating reference and crop evapotranspirat... more This publication presents an updated procedure for calculating reference and crop evapotranspiration from meteorological data and crop coefficients. The procedure, first presented in the FAO Irrigation and Drainage Paper No. 24 'Crop Water Requirements', is termed the 'K c ET o ' approach, whereby the effect of the climate on crop water requirements is given by the reference evapotranspiration ET o and the effect of the crop by the crop coefficient K c. Other procedures developed in FAO Irrigation and Drainage Paper No. 24 such as the estimation of dependable and effective rainfall, the calculation of irrigation requirements and the design of irrigation schedules are not presented in this publication but will be the subject of later papers in the series. iv to derive crop evapotranspiration from ET o are presented. The first approach integrates the relationships between evapotranspiration of the crop and the reference surface into a single K c coefficient. In the second approach, K c is split into two factors that separately describe the evaporation (K e) and transpiration (K cb) components. The selection of the K c approach depends on the purpose of the calculation and the time step on which the calculations are to be executed. The final chapters present procedures that can be used to make adjustments to crop coefficients to account for deviations from standard conditions, such as water and salinity stress, low plant density, environmental factors and management practices. Examples demonstrate the various calculation procedures throughout the publication. Most of the computations, namely all those required for the reference evapotranspiration and the single crop coefficient approach, can be performed using a pocket calculator, calculation sheets and the numerous tables given in the publication. The user may also build computer algorithms, either using a spreadsheet or any programming language. These guidelines are intended to provide guidance to project managers, consultants, irrigation engineers, hydrologists, agronomists, meteorologists and students for the calculation of reference and crop evapotranspiration. They can be used for computing crop water requirements for both irrigated and rainfed agriculture, and for computing water consumption by agricultural and natural vegetation. Crop evapotranspiration v Acknowledgements These guidelines constitute the efforts of eight years of deliberations and consultations by the authors, who together formed the working group to pursue the recommendations of the FAO expert consultation that was held in May 1990 in Rome. The consultation was organized to review the then current FAO guidelines to determine Crop Water Requirements, published in 1977 as FAO Irrigation and Drainage paper No. 24 (FAO-24) and authored by J. Doorenbos and W. Pruitt. The conceptual framework for the revised methodologies introduced in this publication came forth out of the advice of the group of eminent experts congregated in the 1990 meetings and who have importantly contributed to the development of the further studies conducted in the framework of the publication.
Water, Jan 13, 2018
The sustainability of the Hetao Irrigation System, located in the water scarce upper Yellow River... more The sustainability of the Hetao Irrigation System, located in the water scarce upper Yellow River basin, is a priority considering the need for water saving, increased water productivity, and higher farmers' incomes. The upgrading of basin irrigation, the main irrigation method, is essential and includes the adoption of precise land levelling, cutoff management, improved water distribution uniformity, and adequate irrigation scheduling. With this objective, the current study focuses on upgrading wheat basin irrigation through improved design using a decision support system (DSS) model, which considers land parcels characteristics, crop irrigation scheduling, soil infiltration, hydraulic simulation, and environmental and economic impacts. Its use includes outlining water saving scenarios and ranking alternative designs through multi-criteria analysis considering the priorities of stakeholders. The best alternatives concern flat level basins with a 100 and 200 m length and inflow rates between 2 and 4 L s −1 m −1. The total irrigation cost of designed projects, including the cost of the autumn irrigation, varies between 2400 and 3300 Yuan ha −1 ; the major cost component is land levelling, corresponding to 33-46% of total irrigation costs. The economic land productivity is about 18,000 Yuan ha −1. The DSS modelling defined guidelines to be applied by an extension service aimed at implementing better performing irrigation practices, and encouraged a good interaction between farmers and the Water Users Association, thus making easier the implementation of appropriate irrigation management programs.
InTech eBooks, Sep 6, 2011
Efficient Decision Support Systems-Practice and Challenges in Multidisciplinary Domains 292 irrig... more Efficient Decision Support Systems-Practice and Challenges in Multidisciplinary Domains 292 irrigation include the BORDER model (Strelkoff et al., 1996). The models SRFR (Strelkoff, 1993) and SIRMOD (Walker, 1998) apply to furrows, basin and border irrigation and adopt various approaches for solving the continuity and momentum equations. Reviews were recently produced by Pereira et al. (2006) and Strelkoff & Clemmens (2007). In addition to hydraulics simulation models, surface irrigation design requires the application of other type of models such as for irrigation scheduling, land leveling, distribution systems, and cost and environmental analysis. In practice, it is usually difficult to manage data for an interactive application of these models in design when they are not integrated with a common database. The decision support systems (DSS) methodology provides the framework to explore the synergy between mathematical simulation models, data and user knowledge through its integration aimed to help the decision-maker to solve complex problems. The DSS methodology makes handling data of various types easier and effective, and favors the integration of simulation models and their interactive application. It provides for a decision-maker learning process and it supports a decision process and related choices through multicriteria analysis. DSS models are often applied to irrigation planning and policy analysis (
Agrociencia
Barley is usually cropped during the Winter-Spring season and may require supplemental irrigation... more Barley is usually cropped during the Winter-Spring season and may require supplemental irrigation in dry years. When malt barley is cropped for the industry, irrigation is used to achieve high commercial yields taking into consideration that irrigation should be ceased about one month prior to harvesting in order to achieve high malt quality. Data from two crop seasons of Hordeum vulgare L. cv. Publican, one dry and the second wet, cropped in a farmer's field located in the Ribatejo region, Portugal, were used for calibrating and validating the SIMDualKc soil water balance model, to assess the ability of a simplified approach (SIMDualKc model coupled with the Stewart's global model) for grain yield predictions and to parameterize and test the AquaCrop crop growth and yield model. The SIMDualKc model calibration consisted in deriving the basal crop coefficients (Kcb) and depletion fractions for no stress (p) along the crop growth stages using available soil water (ASW) observ...
Agricultural Water Management
Jute mallow (Corchorus olitorius L.) is an annual crop grown for human consumption of its nutriti... more Jute mallow (Corchorus olitorius L.) is an annual crop grown for human consumption of its nutritious leaves in many regions of the world. Despite its importance for household food security and farmers' income, reliable information on the crop's water requirements is still quite scarce. To overcome this knowledge gap, the irrigation needs of jute mallow grown in the Akkar region in Syria were investigated. The analysis focused on a three-year period (2017-2019) where the SIMDualKc model was calibrated and validated for simulating soil water contents and computing the soil water balance in jute mallow plots irrigated with basin and drip methods. The model was further used to determine the probabilities of the demand for irrigation water in scenarios considering different crop season lengths, irrigation methods, and application depths over a longer period of 23 years (1998-2020). The SIMDualKc model was able to simulate soil water contents measured in the field plots, returning root mean square error values lower than 0.001 m 3 m-3 and modeling efficiencies ranging from 0.358 to 0.812. The calibrated basal (non-stressed) crop coefficients (K cb) were 0.15, 0.95, and 0.95 for the initial (K cb ini), mid-season (K cb mid), and end-season (K cb end) stages, respectively. The crop was harvested twice per season, with the drip treatments presenting the highest water productivity and economic indicators. In contrast, the basin treatment resulted in substantial percolation losses, which affected yields and indicators. Although net irrigation requirements showed a large variation for the extremes of the long-term weather time series, differences between the years representing average water demand and those representing very high water demand were only found for the drip irrigation scenarios. This study contributes to improving irrigation water management of jute mallow in the Syrian Akkar region, and for the sustainability of local production systems.
Excess water is often applied to horticultural crops irrigation, which contributes to inefficient... more Excess water is often applied to horticultural crops irrigation, which contributes to inefficient water use and lower yields in horticultural production. However, these problems may be controlled when improved irrigation scheduling is adopted. The water balance and irrigation scheduling simulation model ISAREG was selected for searching improved irrigation schedules for selected horticultural crops in Cuba. The calibration and validation of the model was first performed using two independent data sets for each studied crop. The calibration refers to the crop coefficients (Kc) and the soil water depletion fraction for no stress (p). Results show a good agreement between observed and model predicted available soil water, with the root mean square error ranging 0.97 – 2.82 mm, and a index of agreement ranging 0.93 0.99. After this calibration and validation process the simulation model ISAREG was used to analyze the current irrigation schedules and develop appropriate alternatives that...
Water resources management in the Yellow River basin, China, is facing a paradigmatic change in c... more Water resources management in the Yellow River basin, China, is facing a paradigmatic change in consequence of an unbalanced supply and demand due to an increased demand for water from non-agricultural sectors and a reduced supply due to climate change that reduced precipitation and increased climatic demand. The problem is aggravated by low equity of spatial water allocation in the basin. A supply reduction in the upstream basin area aims to control the water scarcity conditions occurring in the middle and lower reaches of the basin. Forecasted scenarios on water resources allocation and use for agriculture in the upper reaches of the Yellow River basin point out for the need to reduce irrigation water withdrawal and increasing land and water productivity. This paper focus on the Hetao Irrigation District, Inner Mongolia, in upper reaches of Yellow River, where sustainable water saving irrigation is being implemented in response to global changes occurring in the Yellow River basin...
Revista de Ciências Agrárias, 2013
O presente estudo caracteriza os efeitos de uma conducao tipica de rega em olival superintensivo ... more O presente estudo caracteriza os efeitos de uma conducao tipica de rega em olival superintensivo (1,35 x 3,75 m) na regiao de Evora (Alentejo) e em solo Cambissolo Eutrico. Analisa-se o regime hidrico praticado em dois tratamentos de rega, normal (FI) e deficitario (DI), este com reducao da dotacao de rega depois do endurecimento do caroco e seus efeitos sobre a transpiracao, a humidade do solo e o potencial hidrico, um parâmetro fisiologico indicador do estado hidrico da cultura. Analisam-se os resultados de transpiracao potencial do olival obtidos com o modelo de condutância estomatica global da copa de Orgaz et al. (2007) aplicado ao modelo big leaf de Penman Monteith (Jones, 1992). Analisa-se tambem a possibilidade de prever a transpiracao do olival com os valores do indice de vegetacao NDVI estimados de assinaturas espectrais do olival, obtidos por deteccao remota atraves dos sensores instalados nos satelites Landsat Thematic Mapper e Terra. Em relacao ao regime hidrico da re...
Agricultural Water Management, 2021
The present study reviews the research on the FAO56 crop coefficients of fruit trees and vines pe... more The present study reviews the research on the FAO56 crop coefficients of fruit trees and vines performed over the past twenty years. The main objective was to update information and extend tabulated single (K c) and basal (K cb) standard crop coefficients. The selection and analysis of the literature for this review have been done to consider only studies that adhere to FAO56 method, computing the reference ET with the FAO Penman-Monteith ET o equation and field measuring crop ET with proved accuracy. The crops considered refer to vine fruit crops, berries and hops, temperate climate evergreen fruit trees, temperate climate deciduous fruit trees and, tropical and subtropical fruit crops. Papers satisfying the conditions expressed above, and that studied the crops under pristine or appropriate eustress conditions, were selected to provide for standard K c and K cb data. Preference was given to studies reporting on the fraction of ground cover (f c), crop height (h), planting density, crop age and adopted training systems. The K c and K cb values obtained from the selected literature generally show coherence relative to the crop biophysical characteristics and reflect those characteristics, mainly f c , h and training systems. The ranges of reported K c and K cb values were grouped according to crop density, particularly f c and h, and were compared with FAO56 (Allen et al., 1998) previously tabulated K c and K cb values, as well as by Allen and Pereira (2009) and Jensen and Allen (2016), which lead to define update indicative standard K c and K cb values. These values are aimed for use in crop water requirement computations and modeling for irrigation planning and scheduling, thus also aimed at supporting improved water use and saving in orchards and vines.
Agricultural Water Management, 2016
Intercropping is commonly used in the Hetao irrigation district, upper Yellow River basin, where ... more Intercropping is commonly used in the Hetao irrigation district, upper Yellow River basin, where the main crops are wheat, maize and sunflower. For a better use of land, water, radiation energy, and nutrients, spring wheat is traditionally intercropped with maize (W-M) and, more recently, with sunflower (W-S). Considering the need to reduce diversions of water for irrigation in Hetao, this study aims to assess crop water use of W-M and W-S intercropping systems in comparison to the same crops in monocropping. The dual crop coefficient approach was adopted with the SIMDualKc model, which allows partitioning crop evapotranspiration into crop transpiration and soil evaporation. A new model approach was tested to compute a combined basal crop coefficient for the intercropping, K cb inter , which uses the daily values of the K cb of the component crops together with the respective heights and fractions of ground covered by the crops. SIMDualKc was first calibrated and validated for wheat, maize and sunflower as single crops using field data of 2010-2012 and was later used with the new developed approach, which was validated with W-M and W-S field data of 2010-2011. The K cb values calibrated for wheat, maize and sunflower compared well with literature and goodness of fit indicators have shown high accuracy of simulations used for calibration and validation. Results evidenced the importance of groundwater contribution in Hetao, and that soil evaporation is there low under surface irrigation. Moreover, it was found that actual evapotranspiration, crop transpiration, irrigation water use and groundwater contribution of intercropping systems were larger than those of the component sole crops, which led to significantly higher yields of intercropping relative to those of single crops.
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Papers by Luís Santos Pereira