Performance of an automatic upstream controlled irrigation system: conveyance efficiencies

This paper presents a study of conveyance efficiencies in the Sorraia Irrigation Project, Portugal. The Irrigation Project is briefly described and flow measurement techniques are analyzed. Results show that efficiencies are higher during week days and normal labour hours and lower during weekends and at night. Water losses are higher than in other similar systems and the main reason is the substitution of the flow rotation method by restricted arranged schedules. An improvement process for saving water and accommodating deliveries to demands is also briefly presente

AVALIAÇÃO DO RISCO DA DEGRADAÇÃO DA QUALIDADE DA ÁGUA EM SISTEMAS PÚBLICOS DE ABASTECIMENTO

A água para consumo humano está sujeita a ameaças desde o seu ponto de captação até ao ponto de consumo, que podem comprometer em diversos graus e formas, a qualidade da água fornecida ao consumidor e originar riscos para a saúde pública. Na actualidade, não é suficiente disponibilizar água em quantidade e pressão adequadas ao longo das 24 horas do dia, pois a sua qualidade é de uma importância crescente para todos os agentes envolvidos. A gestão do risco aplicada à qualidade da água assume, assim, uma importância superior, sendo necessária e emergente a discussão apresentada neste trabalho, sobre a problemática da avaliação e gestão do risco da qualidade da água em sistemas públicos de abastecimento procurando que o risco seja minimizado. Neste trabalho começa-se pela adaptação do conceito técnico do risco à qualidade da água para consumo humano em sistemas públicos de abastecimento. Não sendo o risco percepcionado necessariamente coincidente com o risco real, discutir-se-ão os mecanismos que influenciam a percepção da qualidade da água pelo consumidor e respectivos riscos para a saúde humana. Na sequência desta abordagem ao tema, pretende-se apresentar as ameaças e riscos a que a qualidade da água num sistema de abastecimento está sujeita, assim como, as medidas a tomar para a sua prevenção e/ou diminuição. Considerando eficaz a aplicação da metodologia de Gestão do Risco da Norma ISO 31000 à Gestão do Risco da Qualidade da Água para consumo humano em sistemas públicos de abastecimento de água, são apresentadas as considerações finais

3.4 : La gestion du risque barrage-vallée au Portugal

After a review of the risk concept within the present society framework as well as the technology knowledge and public perception, the paper applies that concept to valleys with dams. It is also presented the main concepts related to risk management, valley vulnerability and computational systems developped in Portugal by a NATO research project. Benefits obtained by this project are referred specially in what concerns the civil protection level and the valley safety measures.Après un rappel du concept de risque dans le contexte de la société actuelle par rapport aux connaissances techniques et à la perception du public, la contribution ci-après développe ce concept pour le cas des barrages et des vallées. On présente aussi les principaux concepts concernant la gestion du risque, la vulnérabilité des vallées et les logiciels développés au Portugal dans le cadre d'un projet OTAN de recherche scientifique. Les retombées du projet au niveau de la protection civile et des consignes de sécurité dans les vallées sont également présentées.Betâmio de Almeida António. 3.4 : La gestion du risque barrage-vallée au Portugal. In: Les logiciels de mécanique des fluides au service de l'industrie et de l'environnement. Congrès de la Société Hydrotechnique de France. 26èmes journées de l'hydraulique. Paris-Marne la Vallée, du 11 au 13 septembre 1998. 2000

Tempos de resposta às variações de caudal em canais de rega

Apresenta-se o conceito de tempo de resposta em canais de rega e comenta-se a respectiva variação em função da existência ou não de reguladores de nível no interior dos canais. Apresenta-se um caso real de cálculo que tem em conta o caudal inicial, a amplitude e o sentido da variação provocada. Comentam-se também as implicações do tempo de resposta na gestão hidráulica do canai

Hydraulic state and disturbances estimation in canals. A case study

Social reasons, the new irrigation methods and the water use improvement are the main reasons for changing the rigid water delivery methods by on-demand methods and improve the water conveyance and distribution efficiency. In this domain, there is a great program of rehabilitation and modernization of traditional irrigation systems in Portugal. In this program, have been used the supervisory and real time control. Real time control needs, in each instant, the knowledge of the hydraulic state and external disturbances, only measuring a few state variables. The paper presents a pole placement method to estimate both the state variables and external disturbances (demand delivery). The obtained results are presented to Salvaterra Canal of Sorraia Irrigation Schem

Modelling automatic upstream control with SIMCAR

The model SIMCAR solves the gradually varied unsteady flow in a branched canal network with upstream control, with particular attention given to the simulation of the AMIL radial gates. It is based on the Saint-Venant system of equations, which are solved by a finite-difference technique with a four-point implicit scheme weighted in time and space. model calibration and validation are made for the canal network of the Sorraia Irrigation Project, Portugal

Application of a Numerical Implicit Model to an Irrigation Canal

A case study is presented regarding an application of a computational model to the unsteady flow in an irrigation canal, using an implicit numerical technique. The Saint-Venant equations of continuity and momentum for one-dimensional gradually varied flow were written in a finite-difference form. The system of equations was solved by the double-sweep algorithm. A computer program was written to solve the problem in which a discharge hydrograph is given at the upstream boundary of the canal and a time-dependent water level is specified at the downstream boundary. the model was validated by field tests. A sensitivity analysis was also made concerning the numerical weighting parameter value and the choice of the time step in order to improve the model accuracy. This model will be the basis for an improved canal management in the near futur

Simulation of Transient Flows in Irrigation Canals: Automatic AMIL Radial Gates

The computer model SIMCAR for simulation of upstream controlled canal systems was developed. The model solves the gradually unsteady flow in a branched canal network, regarding the singularities: AMIL radial gates, siphons, transitions and confluences. The model is based on the Saint-Venant systems of equations, which are solved by a four-point linear finite-difference implicit scheme weighted in time and space. The final linear system of equations is solved by the double-sweep algorithm. A numerical approach for submerged and free discharge at the gates are presente