Orientador: João Carlos Cury Saad / Banca: Roberto Lyra Villas Boas / Banca: Tarlei Arriel Botrel / Banca: Sergio Nascimento Duarte / Banca: Denise Laschi / Resumo: A irrigação é prática fundamental para o cultivo de crisântemo, porém seu manejo adequado tem sido negligenciado pelos produtores, resultando em prejuízos no crescimento vegetal e conseqüentes decréscimos na produtividade e na qualidade do produto final. A resposta das plantas à tensão de água no solo tem sido estudada como forma de controle da irrigação, já que irrigações deficitárias refletem diretamente na redução da produtividade, enquanto irrigações excessivas prejudicam a qualidade das flores. Buscando melhor representatividade dos dados obtidos, desenvolveu-se esta pesquisa na propriedade Steltenpool, no Distrito de Holambra II, município de Paranapanema-SP, em cultivos rotineiramente desenvolvidos pelo produtor. O objetivo principal deste experimento foi identificar a tensão de água no solo que pudesse resultar na melhor qualidade comercial do crisântemo de corte, cultivar Dark Orange Reagan. O delineamento experimental adotado foi inteiramente casualizado com 3 repetições, dividido em 30 parcelas, cada uma controlada por registro, com 4 fitas gotejadoras. Os tratamentos foram definidos por dez níveis de tensão de água no solo: 5, 10, 15, 20, 25, 30, 35, 40, 45 e 50 kPa. Foram realizadas avaliações da área foliar, matéria seca, diâmetro e altura das plantas, em intervalos de 14 dias, utilizando-se 3 plantas por parcela, escolhidas ao acaso, a partir dos quais se realizou análise de crescimento. Os resultados demonstram não haver diferença significativa entre os tratamentos para a maioria dos parâmetros avaliados. Os tratamentos irrigados com as tensões 20 e 50 kPa resultaram na maior produção de matéria seca e no maior número de pacotes A1, ou seja, com 2 o melhor padrão de qualidade. A maior durabilidade pós-colheita foi obtida com o emprego da giberelina (GA3) nas tensões de 30 e 50 kPa. / Abstract: Irrigation is an important practice for chrysantemum growing, but most of growers didnþt adopt any kind of water scheduling and it results in yield reduction and quality lost of the final product. Soil water tension has been used with success as a criterion of irrigation scheduling. It avoids the excessive application that frequently results in lost of quality. Looking for the best representation of the obtained data, this research was developed in the denominated property Steltenpool, in the municipal district of Holambra II, area of Paranapanema-SP, in cultivations developed by the producer. The aim of this research was identify the soil water tension that results in the best quality of the cut chrysanthemum, Dark Orange Reagan cultivar. Experimental design was totally randomized with 3 repetitions, subdivided in 30 parcels, each one controlled by a register, with drip tape lines. Treatments were defined for 10 soil water tension levels: 5, 10, 15, 20, 25, 30, 35, 40, 45 e 50 kPa. Evaluations of leaves area, dried weight, diameter and plants high were done each 14 days period, using 3 plants per parcel that were used in growing analysis. Results showed that there is no difference among treatments for most of the evaluated variables. Plants irrigated with soil water tensions of 20 and 50 kPa showed the biggest dried weight and in highest number of A1 pack that means the highest quality. The longest durability was obtained with gibberellin (GA3) associated with soil water tensions of 30 and 50 kPa. / Doutor

OLIVEIRA, Antônio Dimas Simão de. Avaliação do sensor de umidade TOPDEA no manejo da irrigação. 2008. 71 f. : Dissertação (mestrado) - Universidade Federal do Ceará, Centro de Ciências Agrárias, Departamento de Engenharia Agrícola, Progarma de Pós-Graduação em Engenharia de Agrícola, Fortaleza-CE, 2008. / Submitted by demia Maia (demiamlm@gmail.com) on 2016-06-14T12:51:05Z No. of bitstreams: 1 2008_dis_adsoliveira.pdf: 13748562 bytes, checksum: 57833bde003cd50858fd12de77a6e763 (MD5) / Approved for entry into archive by demia Maia (demiamlm@gmail.com) on 2016-06-14T12:51:34Z (GMT) No. of bitstreams: 1 2008_dis_adsoliveira.pdf: 13748562 bytes, checksum: 57833bde003cd50858fd12de77a6e763 (MD5) / Made available in DSpace on 2016-06-14T12:51:34Z (GMT). No. of bitstreams: 1 2008_dis_adsoliveira.pdf: 13748562 bytes, checksum: 57833bde003cd50858fd12de77a6e763 (MD5) Previous issue date: 2008 / The scientific community, in recent years, has intensified studies to measure the impacts to the environment caused by pollution, mainly the adverse effects to air and water. The fact that less than 1% of the global water resources is comprised of drinking water and available at the surface of the earth makes it a commodity of conflict. According to the FAO by 2030 to meet the demand caused by the growth of the world population a 14% increase in available drinking water will be required for irrigation. To meet that expectation, the classical questions of when and how much to irrigate needs to be assessed. Thus, professionals in the fields of engineering have especially focused on practices to increase the efficiency of irrigation. This study aimed at evaluating a moisture sensor, a capacitive type, called TOPDEA, in irrigation management. The soil moisture is the most basic index to quantify water in a soil, expressed in units of mass or volume. The monitoring of the soil moisture is one of the most important factors for proper irrigation management. The experiment was carried out in the Irrigated Perimeter of the Lower Acaraú Basin – Ceará, in two different fields: The first one cultivated with bananas where preliminary tests were conducted to evaluate the sensor calibration, and the second one with watermelon for irrigation scheduling. The sensors were calibrated by means of the regression analysis between moisture and frequency output of the sensors from saturation to approximately 4% moisture content. The calibration was validated by comparing resulting irrigation timing produced by scheduling the irrigation with sensors and with a weather station. The number of sensors per hactare was analyzed by analyzing the timing of irrigation for each additional sensor in the field. The effect of the placement of the sensors (position in relation to the dripper and plant) was evaluated. The calibration equation for the sensor was found to be potential ( 1778371018 −2,3894213 q = f ). The highest readings occurred with frequency of the sensor installed 25.3 cm from the emitter, while the lowest occurred at 19.85 cm. The largest irrigation time was found when two sensors were used for each hectare, while the lowest was found using five sensors per hectare. The total irrigation depth with the scheduling conducted with capacitive sensors was 377.96 mm, which resulted in a total volume of 532.17 m³ of water in the entire cycle of watermelon. Crop yield was 36.0 t ha-1 and the water efficiency of 0.068 kg L-1. Water productivity was 16.18 to 26.47% higher compared to the irrigation management commonly practiced in the irrigation district for watermelon. Given the characteristic of soil physics with low water storage capacity, the daily irrigation requirement must be fractioned into several irrigation pulses starting early morning and the application of the total daily requirement in one irrigation event during the night (practice commonly conduction in the district to reduce the electricity bill) should be avoided leading to inefficient of irrigation. The distance between the sensor and the emitter has direct influence on its output. The TOPDEA sensor has proven to be accurate and efficient in the management of irrigation. / A comunidade científica mundial, nos últimos anos, tem intensificado os estudos para mensurar os impactos causados ao ambiente pela poluição, principalmente os efeitos adversos ao ar e água. O fato de menos de 1% da água ser potável e estar disponível à superfície da terra torna a mesma um bem de conflito. Segundo a FAO até 2030 será necessário um incremento de 14% da água potável, na irrigação, a fim de suprir a demanda provocada pelo crescimento da população mundial. Um dos problemas clássicos, no manejo da irrigação, é determinar quando e quanto irrigar e no intuito de sanar tal problema, profissionais da área de engenharia buscam cada vez mais, através de pesquisas, aumentar a eficiência de irrigação. O presente trabalho teve como objetivo avaliar um sensor de umidade, do tipo capacitivo, denominado TOPDEA, no manejo da irrigação. A umidade do solo é o indicador mais básico da água em uma amostra de solo. O monitoramento da umidade do solo é um dos fatores mais importantes para manejo correto da irrigação, contribuindo de forma direta para a determinação de quando e quanto irrigar. O experimento foi realizado no Perímetro Irrigado do Baixo Acaraú – Ceará, em duas áreas distintas: A primeira com banana para ensaios preliminares de campo e avaliação da equação de calibração do sensor e a segunda com melancia para o manejo da irrigação propriamente dito. Os sensores foram calibrados através de análise de regressão entre umidade e freqüência produzida pelos mesmos, partindo do ponto de saturação até aproximadamente 4% de umidade. A avaliação da equação de calibração ocorreu através da comparação entre os dados dos sensores e os dados da estação meteorológica, para tempo de irrigação. O número de sensores por hectare foi analisado pela comparação entre o número de sensores por hectare e seus respectivos tempos de irrigação. O efeito geométrico da distância de instalação dos sensores, em relação aos emissores, foi analisado através do teste de médias das leituras com as respectivas distâncias de instalação. A equação de calibração para a umidade foi do tipo potencial ( 1778371018 −2,3894213 q = f ). As maiores leituras de frequência ocorreram com o sensor instalado a 25,3 cm do emissor, enquanto que as menores ocorreram a 19,85 cm. Os maiores tempos de funcionamento do sistema de irrigação ocorreram utilizando-se dois sensores por hectares, enquanto os menores tempos ocorreram utilizando-se cinco sensores por hectare. A lâmina total de irrigação utilizando-se sensores foi de 377,96 mm, o que resultou em um volume total de água igual a 532,17 m³ para todo o ciclo da cultura. A produtividade foi de 36,0 t ha-1 e a eficiência do uso da água foi de 0,068 kg L-1. A produtividade da água foi de 16,18 a 26,47% superior àquela obtida com o manejo da irrigação local praticado no perímetro para a cultura da melancia. Dada a característica de armazenamento do solo, deve-se fracionar a irrigação com a primeira ocorrendo nas primeiras horas da manhã. Assim, a irrigação noturna de uma grande lâmina (prática comum do Perímetro) conduz à ineficiência da irrigação. A distância entre o sensor e o emissor tem influência direta da resposta do mesmo. O sensor TOPDEA mostrou-se preciso e eficiente no manejo da irrigação.

Made available in DSpace on 2014-06-11T19:32:43Z (GMT). No. of bitstreams: 0 Previous issue date: 2006-02-06Bitstream added on 2014-06-13T20:43:46Z : No. of bitstreams: 1 farias_mf_dr_botfca.pdf: 610419 bytes, checksum: 276016d016772019969a7ff54d9cfcd3 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Universidade Estadual Paulista (UNESP) / A irrigação é prática fundamental para o cultivo de crisântemo, porém seu manejo adequado tem sido negligenciado pelos produtores, resultando em prejuízos no crescimento vegetal e conseqüentes decréscimos na produtividade e na qualidade do produto final. A resposta das plantas à tensão de água no solo tem sido estudada como forma de controle da irrigação, já que irrigações deficitárias refletem diretamente na redução da produtividade, enquanto irrigações excessivas prejudicam a qualidade das flores. Buscando melhor representatividade dos dados obtidos, desenvolveu-se esta pesquisa na propriedade Steltenpool, no Distrito de Holambra II, município de Paranapanema-SP, em cultivos rotineiramente desenvolvidos pelo produtor. O objetivo principal deste experimento foi identificar a tensão de água no solo que pudesse resultar na melhor qualidade comercial do crisântemo de corte, cultivar Dark Orange Reagan. O delineamento experimental adotado foi inteiramente casualizado com 3 repetições, dividido em 30 parcelas, cada uma controlada por registro, com 4 fitas gotejadoras. Os tratamentos foram definidos por dez níveis de tensão de água no solo: 5, 10, 15, 20, 25, 30, 35, 40, 45 e 50 kPa. Foram realizadas avaliações da área foliar, matéria seca, diâmetro e altura das plantas, em intervalos de 14 dias, utilizando-se 3 plantas por parcela, escolhidas ao acaso, a partir dos quais se realizou análise de crescimento. Os resultados demonstram não haver diferença significativa entre os tratamentos para a maioria dos parâmetros avaliados. Os tratamentos irrigados com as tensões 20 e 50 kPa resultaram na maior produção de matéria seca e no maior número de pacotes A1, ou seja, com 2 o melhor padrão de qualidade. A maior durabilidade pós-colheita foi obtida com o emprego da giberelina (GA3) nas tensões de 30 e 50 kPa. / Irrigation is an important practice for chrysantemum growing, but most of growers didnþt adopt any kind of water scheduling and it results in yield reduction and quality lost of the final product. Soil water tension has been used with success as a criterion of irrigation scheduling. It avoids the excessive application that frequently results in lost of quality. Looking for the best representation of the obtained data, this research was developed in the denominated property Steltenpool, in the municipal district of Holambra II, area of Paranapanema-SP, in cultivations developed by the producer. The aim of this research was identify the soil water tension that results in the best quality of the cut chrysanthemum, Dark Orange Reagan cultivar. Experimental design was totally randomized with 3 repetitions, subdivided in 30 parcels, each one controlled by a register, with drip tape lines. Treatments were defined for 10 soil water tension levels: 5, 10, 15, 20, 25, 30, 35, 40, 45 e 50 kPa. Evaluations of leaves area, dried weight, diameter and plants high were done each 14 days period, using 3 plants per parcel that were used in growing analysis. Results showed that there is no difference among treatments for most of the evaluated variables. Plants irrigated with soil water tensions of 20 and 50 kPa showed the biggest dried weight and in highest number of A1 pack that means the highest quality. The longest durability was obtained with gibberellin (GA3) associated with soil water tensions of 30 and 50 kPa.

Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico / A comunidade cientÃfica mundial, nos Ãltimos anos, tem intensificado os estudos para mensurar os impactos causados ao ambiente pela poluiÃÃo, principalmente os efeitos adversos ao ar e Ãgua. O fato de menos de 1% da Ãgua ser potÃvel e estar disponÃvel à superfÃcie da terra torna a mesma um bem de conflito. Segundo a FAO atà 2030 serà necessÃrio um incremento de 14% da Ãgua potÃvel, na irrigaÃÃo, a fim de suprir a demanda provocada pelo crescimento da populaÃÃo mundial. Um dos problemas clÃssicos, no manejo da irrigaÃÃo, à determinar quando e quanto irrigar e no intuito de sanar tal problema, profissionais da Ãrea de engenharia buscam cada vez mais, atravÃs de pesquisas, aumentar a eficiÃncia de irrigaÃÃo. O presente trabalho teve como objetivo avaliar um sensor de umidade, do tipo capacitivo, denominado TOPDEA, no manejo da irrigaÃÃo. A umidade do solo à o indicador mais bÃsico da Ãgua em uma amostra de solo. O monitoramento da umidade do solo à um dos fatores mais importantes para manejo correto da irrigaÃÃo, contribuindo de forma direta para a determinaÃÃo de quando e quanto irrigar. O experimento foi realizado no PerÃmetro Irrigado do Baixo Acaraà â CearÃ, em duas Ãreas distintas: A primeira com banana para ensaios preliminares de campo e avaliaÃÃo da equaÃÃo de calibraÃÃo do sensor e a segunda com melancia para o manejo da irrigaÃÃo propriamente dito. Os sensores foram calibrados atravÃs de anÃlise de regressÃo entre umidade e freqÃÃncia produzida pelos mesmos, partindo do ponto de saturaÃÃo atà aproximadamente 4% de umidade. A avaliaÃÃo da equaÃÃo de calibraÃÃo ocorreu atravÃs da comparaÃÃo entre os dados dos sensores e os dados da estaÃÃo meteorolÃgica, para tempo de irrigaÃÃo. O nÃmero de sensores por hectare foi analisado pela comparaÃÃo entre o nÃmero de sensores por hectare e seus respectivos tempos de irrigaÃÃo. O efeito geomÃtrico da distÃncia de instalaÃÃo dos sensores, em relaÃÃo aos emissores, foi analisado atravÃs do teste de mÃdias das leituras com as respectivas distÃncias de instalaÃÃo. A equaÃÃo de calibraÃÃo para a umidade foi do tipo potencial ( 1778371018 −2,3894213 q = f ). As maiores leituras de frequÃncia ocorreram com o sensor instalado a 25,3 cm do emissor, enquanto que as menores ocorreram a 19,85 cm. Os maiores tempos de funcionamento do sistema de irrigaÃÃo ocorreram utilizando-se dois sensores por hectares, enquanto os menores tempos ocorreram utilizando-se cinco sensores por hectare. A lÃmina total de irrigaÃÃo utilizando-se sensores foi de 377,96 mm, o que resultou em um volume total de Ãgua igual a 532,17 m para todo o ciclo da cultura. A produtividade foi de 36,0 t ha-1 e a eficiÃncia do uso da Ãgua foi de 0,068 kg L-1. A produtividade da Ãgua foi de 16,18 a 26,47% superior Ãquela obtida com o manejo da irrigaÃÃo local praticado no perÃmetro para a cultura da melancia. Dada a caracterÃstica de armazenamento do solo, deve-se fracionar a irrigaÃÃo com a primeira ocorrendo nas primeiras horas da manhÃ. Assim, a irrigaÃÃo noturna de uma grande lÃmina (prÃtica comum do PerÃmetro) conduz à ineficiÃncia da irrigaÃÃo. A distÃncia entre o sensor e o emissor tem influÃncia direta da resposta do mesmo. O sensor TOPDEA mostrou-se preciso e eficiente no manejo da irrigaÃÃo. / The scientific community, in recent years, has intensified studies to measure the impacts to the environment caused by pollution, mainly the adverse effects to air and water. The fact that less than 1% of the global water resources is comprised of drinking water and available at the surface of the earth makes it a commodity of conflict. According to the FAO by 2030 to meet the demand caused by the growth of the world population a 14% increase in available drinking water will be required for irrigation. To meet that expectation, the classical questions of when and how much to irrigate needs to be assessed. Thus, professionals in the fields of engineering have especially focused on practices to increase the efficiency of irrigation. This study aimed at evaluating a moisture sensor, a capacitive type, called TOPDEA, in irrigation management. The soil moisture is the most basic index to quantify water in a soil, expressed in units of mass or volume. The monitoring of the soil moisture is one of the most important factors for proper irrigation management. The experiment was carried out in the Irrigated Perimeter of the Lower Acaraà Basin â CearÃ, in two different fields: The first one cultivated with bananas where preliminary tests were conducted to evaluate the sensor calibration, and the second one with watermelon for irrigation scheduling. The sensors were calibrated by means of the regression analysis between moisture and frequency output of the sensors from saturation to approximately 4% moisture content. The calibration was validated by comparing resulting irrigation timing produced by scheduling the irrigation with sensors and with a weather station. The number of sensors per hactare was analyzed by analyzing the timing of irrigation for each additional sensor in the field. The effect of the placement of the sensors (position in relation to the dripper and plant) was evaluated. The calibration equation for the sensor was found to be potential ( 1778371018 −2,3894213 q = f ). The highest readings occurred with frequency of the sensor installed 25.3 cm from the emitter, while the lowest occurred at 19.85 cm. The largest irrigation time was found when two sensors were used for each hectare, while the lowest was found using five sensors per hectare. The total irrigation depth with the scheduling conducted with capacitive sensors was 377.96 mm, which resulted in a total volume of 532.17 m of water in the entire cycle of watermelon. Crop yield was 36.0 t ha-1 and the water efficiency of 0.068 kg L-1. Water productivity was 16.18 to 26.47% higher compared to the irrigation management commonly practiced in the irrigation district for watermelon. Given the characteristic of soil physics with low water storage capacity, the daily irrigation requirement must be fractioned into several irrigation pulses starting early morning and the application of the total daily requirement in one irrigation event during the night (practice commonly conduction in the district to reduce the electricity bill) should be avoided leading to inefficient of irrigation. The distance between the sensor and the emitter has direct influence on its output. The TOPDEA sensor has proven to be accurate and efficient in the management of irrigation.

By using the Soil Conservation Service (SCS) “polynomial” method for corn in the Mississippi Irrigation Scheduling Tool (MIST), the total number of irrigations required during the growing season can be reduced depending on the variety, growing degree days required to reach maturity, and the length of the growing season. Results showed that even though the SCS method called for irrigations earlier in the season, the method did not trigger irrigation events after the crop reached physiological maturity. In addition, although changing the timing of model initiation (planting vs emergence) was not important on the total crop water use, it may have other benefits. Lastly, Watermark 200SS sensors generally did not trigger similar irrigation events, especially around the mid-season, but shallower sensors somewhat matched and showed similar trends with the MIST modeled results and irrigation records. Therefore, using MIST with sensors may be beneficial when making precise irrigation scheduling decisions.

Doctor of Philosophy / Department of Agricultural Economics / Jeffrey M. Peterson / The High Plains aquifer is a primary source of irrigation in western Kansas. Since World War II, producers increased irrigation and the irrigated acreage with the widespread adoption of newer irrigation technologies, causing a reduction in the saturated thickness of the High Plains aquifer. In an effort to conserve water and reduce further decline of the aquifer, the state of Kansas administered cost-share programs to producers who upgraded to an efficient irrigation system. But evidence suggests that the efforts to reduce water consumption have been undermined by producers, who under certain conditions have increased irrigation and irrigated acreage of high-valued and water-intensive crops. The state of Kansas is in a quandary to reduce water consumption and stabilize the saturated thickness of the aquifer while maintaining the economic viability of irrigated agriculture. A producer is faced with the choice of crop, irrigation timing and irrigation technology at the start of the season. This research identifies the conditions for risk-efficient crop choices and estimates the effect of an irrigation technology upgrade on the aquifer. Simulation models based on data from Tribune, Kansas were executed under various scenarios, varying by crop (corn or sorghum), irrigation system (conventional center-pivot or center-pivot with drop nozzles) and well capacity (190, 285 or 570 gallons per minute). Each well capacity was associated with a pre-season soil moisture level (0.40, 0.60 or 0.80 of field capacity). Each scenario was simulated over weather data observed during the 36-year period (1971-2006). Results indicate that producers with slower wells could maximize their net returns while conserving water by choosing less water-intensive crops like sorghum, while irrigating with a conventional center-pivot irrigation system. Producers with faster wells could maximize net returns by choosing water-intensive crops like corn and irrigate with the more efficient center-pivot with drop nozzle irrigation system. In order to reduce groundwater consumption and maintain the saturated thickness of the aquifer, water policies should internalize the interests of all stakeholders and be a combination of irrigation technology, economic factors, hydrological conditions, agronomic practices, conservation practices and local dynamics of the region.

The actual evapotranspiration rate for wheat at the Campus Agriculture Center (CAC) and alfalfa at the Maricopa Agricultural Center (MAC) were measured using the Bowen ratio technique for near real-time irrigation scheduling. The Bowen ratio method underestimated evapotranspiration when compared with AZMET and Penman data. There were problems with the hygrometer and the net radiometer which might have caused this underestimation. The height-fetch ratio requirement was not met, and this may have affected the data. Irrigation scheduling programs and the technique to schedule irrigation in a near real-time were developed. Irrigation programs were not field tested because of the problem with field data. Simulated data was successfully used to demonstrate its application. It was found that irrigation could be scheduled in a near real-time with the programs provided reliable data and proper data acquisition systems are used.

Thesis (M.S.)--Michigan State University. Dept. of Forestry, 2008. / "Major professor, Dr. Pascal Nzokou"--Acknowledgements. Title from PDF t.p. (viewed on July 30, 2009) Includes bibliographical references. Also issued in print.

La plupart des réseaux d'irrigation gravitaire traditionnels, encore majoritaires dans le monde, distribuent l'eau aux parcelles agricoles à travers un réseau de canaux à surface libre. La distribution de l'eau sur ce type de réseau suit en général le mode de distribution au tour d'eau (tour d'eau fixe, modulé, arrangé ou mixte) et nécessite de définir un planning de manœuvre des vannes et un calendrier d'arrosage. La performance de la distribution d'eau est généralement très faible, du fait de contraintes de l'infrastructure, de main d'œuvre et d'évolutions des demandes en eau.La thèse propose une méthode générique permettant d'optimiser les manœuvres des vannes et le calendrier d'arrosage, ainsi que des stratégies de modernisation basées sur la mise en place de vannes automatiques et réservoirs tampon.La méthode est basée sur la programmation linéaire en variables mixtes (MILP). La définition des contraintes et des objectifs s'appuie sur l'analyse de deux périmètres traditionnels du Sud de la France, ainsi que sur une description des principales caractéristiques hydrauliques des systèmes de transport d'eau. Les méthodes prennent en compte trois critères d'optimisation : l'adéquation, la main d'œuvre et l'efficience hydraulique, ces critères pouvant être pondérés pour tenir compte de priorités.La méthode développée est testée sur un réseau virtuel, puis appliquée à un système réel où les évolutions récentes ont profondément dégradé l'adéquation offre-demande. La méthode permet alors de réduire fortement les volumes d'eau prélevés en tête de réseau mais non utilisés par les usagers, tout en assurant une très bonne adéquation offre-demande.L'enjeu de la modernisation des réseaux traditionnels est abordé sur un réseau au tour d'eau fixe, fortement contraint par la charge de travail pour manœuvrer les ouvrages. On montre, sur un site réel, comment définir des priorités de mise en place de vannes automatiques. Dans d'autres cas, la modernisation peut se faire par la mise en place de réservoirs tampon dont l'emplacement et le volume peuvent être optimisés. / Most traditional gravity irrigation networks, still the majority in the world, deliver water to farm field (offtakes) through an open channel network. Water distribution on this type of network is generally based on irrigation schedule/delivery methods (fixed rotation, central system, arranged or mixed schedule) and requires two schedules: one for irrigation and another for gate operations. Water distribution performance of this system is low due to hydraulics infrastructures constraints, manpower and water demand evolution.The thesis proposes a generic method for optimizing gate operations and irrigation schedules, as well as modernization strategies based on the development of automated gates and buffer reservoirs.The method uses mixed integer linear programming (MILP). The definition of constraints and objectives is based on the analysis of two traditional irrigation networks of Southern France, as well as a description of the main characteristics of hydraulic systems for water delivery. Methods take into account three optimization criteria: adequacy, hydraulic efficiency and manpower. These criteria can be weighted for setting the priorities.The developed method is tested on a virtual network, and then applied to a real system where recent evolution have profoundly damaged the adequacy between supply and demand. We show that the method can greatly reduce the volume of water withdrawn by the network, and not used by users, for ensuring a good adequacy between supply and demand.The challenge of modernization is taken into account for an open channel network which is strongly constrained by manpower for gates operations. It is shown on a real network, how to set priorities for implementation of automatic gates. In other cases, the modernization may be achieved by the implementation of the buffer reservoir which location and volume can be optimized.

Submitted in fulfilment of the requirements of the Degree of Doctor of Engineering, Durban University of Technology, 2017. / Water is an essential natural resource for human existence and survival on the earth. South Africa, a water stressed country, allocates a high percentage of its available consumptive water use to irrigation. Therefore, it is necessary that we optimize water use in order to enhance food security. This study presents the development of mathematical models for irrigation scheduling of crops, optimal irrigation water release and crop yields in Vaal Harts irrigation scheme (VIS) of South Africa. For efficient irrigation water management, an accurate estimation of reference evapotranspiration (ETₒ) should be carried out. However, due to non-availability of enough historical data for the study area, mathematical models were developed to estimate ETₒ. A 20-year monthly meteorological data was collected and analysed using two data–driven modeling techniques namely principal component analysis (PCA) and adaptive neuro-fuzzy inference systems (ANFIS). Furthermore, an artificial neural network (ANN) model was developed for real time prediction of future ETₒ for the study area. The real time irrigation scheduling of potatoes was developed using a crop growth simulation model called CROPWAT. It was used to determine the crop water productivity (CWP), which is a determinant of the relationship between water applied and crop yield. Finally, a new and novel evolutionary multi-objective optimization algorithm called combined Pareto multi-objective differential evolution (CPMDE) was applied to optimize irrigation water use and crop yield on the VIS farmland. The net irrigation benefit, land area and irrigation water use of maize, potatoes and groundnut were optimized. Results obtained show that ETₒ increases with temperature and windspeed. Other variables such as rainfall and relative humidity have less significance on the value of ETₒ. Also, ANN models with one hidden layer showed better predictive performance compared with other considered configurations. A 5-day time step irrigation schedule data and graphs showing the crop water requirements and irrigation water requirements was generated. This would enable farmers know when, where, and how much water to apply to a given farmland. Finally, the employed CPMDE optimization algorithm produced a set of non-dominated Pareto optimal solutions. The best solution suggests that maize, groundnut and potatoes should be planted on 403543.44 m2, 181542.00 m2 and 352876.05 m2areas of land respectively. This solution generates a total net benefit of ZAR 767,961.49, total planting area of 937961.49 m2 and irrigation water volume of 391,061.52 m3. Among the three crops optimized, maize has the greatest land area, followed by potatoes and groundnut. This shows that maize is more profitable than potatoes and groundnut with respect to crop yield and water use in the study area. / D