Guillermo Palau-Salvador

Generalization of ETo ANN Models through Data Supplanting

This paper describes the application of artificial neural networks (ANNs) for estimating reference evapotranspiration ( ETo ) as a function of local maximum and minimum air temperatures as well as exogenous relative humidity and reference evapotranspiration in different continental contexts of the autonomous Valencia region, on the Spanish Mediterranean coast. The development of new and more precise models for ETo prediction from minimum climatic data is required, since the application of existing methods that provide acceptable results is limited to those places where large amounts of reliable climatic data are available. The Penman-Monteith model for ETo prediction, proposed by the FAO as the sole standard method for ETo estimation, was used to provide the ANN targets for the training and testing processes. Concerning models which demand scant climatic inputs, the proposed model provides performances with lower associated errors than the currently existing temperature-based models, which only consider l...

Three-Dimensional Modeling and Geometrical Influence on the Hydraulic Performance of a Control Valve

The ability to understand and manage the performance of hydraulic control valves is important in many automatic and manual industrial processes. The use of computational fluid dynamics (CFD) aids in the design of such valves by inexpensively providing insight into flow patterns, potential noise sources, and cavitation. Applications of CFD to study the performance of complex three-dimensional (3D) valves, such as poppet, spool, and butterfly valves, are becoming more common. Still, validation and accuracy remain an issue. The Reynolds-averaged Navier-Stokes equations were solved numerically using the commercial CFD package FLUENT V6.2 to assess the effect of geometry on the performance of a 3D control valve. The influence of the turbulence model and of a cavitation model was also investigated. Comparisons were made to experimental data when available. The 3D model of the valve was constructed by decomposing the valve into several subdomains. Agreement between the numerical predictions and measurements of flow pressure was less than 6% for all cases studied. Passive flow control, designed to minimize vortical structures at the piston exit and reduce potential cavitation, noise, and vibrations, was achieved by geometric smoothing. In addition, these changes helped to increase C υ and reduce the area affected by cavitation as it is related to the jet shape originated at the valve throat. The importance of accounting for full 3D geometry effects in modeling and optimizing control valve performance was demonstrated via CFD. This is particularly important in the vicinity of the piston. It is worth noting that the original geometry resulted in a lower C υ with higher velocity magnitude within the valve, whereas after smoothing C υ increased and served to delay cavitation inception.

Integrated Emitter Local Loss Prediction Using Artificial Neural Networks

This paper describes an application of artificial neural networks (ANNs) to the prediction of local losses from integrated emitters. First, the optimum input-output combination was determined. Then, the mapping capability of ANNs and regression models was compared. Afterwards, a five-input ANN model, which considers pipe and emitter internal diameter, emitter length, emitter spacing, and pipe discharge, was used to develop a local losses predicting tool which was obtained from different training strategies while taking into account a completely independent test set. Finally, a performance index was evaluated for the test emitter models studied. Emitter data with low reliability were removed from the process. Performance indexes over 80% were obtained for the remaining test emitters.

Influence of the secondary motions on pollutant mixing in a meandering open channel flow

This paper presents large eddy simulation of turbulent flow in a meandering open channel with smooth wall and rectangular cross-section. The Reynolds number based on the channel height is 40,000 and the aspect ratio of the cross-section is 4.48. The depth-averaged mean stream-wise velocity agree well to experimental measurements. In this specific case, two interacting cells are formed that swap from one bend to the other. Transport and mixing of a pollutant is analysed using three different positions of release, e.g. on the inner bank, on the outer bank and on the centre of the cross section. The obtained depth-average mean concentration profiles are reasonably consistent with available experimental data. The role of the secondary motions in the mixing processes is the main focus of the discussion. It is found that the mixing when the scalar is released on the centre of the cross-section is stronger and faster than the mixing of the scalar released on the sides. When the position of release is close to a bank side, the mixing is weaker and a clear concentration of scalar close to the corresponding side-wall can be observed in both cases.

Numerical simulation of the hydrodynamics and turbulent mixing process in a drinking water storage tank

ABSTRACT Jet-mixing and residence time in a rectangular water storage tank with a constant water level are investigated using the tools of Computational Fluid Dynamics (CFD). A set of Unsteady Reynolds-Averaged Navier-Stokes (URANS) equations using a realisable k-ε model for different inlet configurations has been used. Numerical simulations were validated by means of experimental measurements. A saline inflow was simulated and the computed salinity in the outflow was compared with the measured values, with the aim of improving the tank performance based only on simple modifications of the inlet position and inflow rate. The results show that the URANS technique is able to adequately capture the experimental dilution curve measured at the outlet of the tank. The residence time is mainly influenced by advective transport. Modifications of the horizontal angle and Reynolds number of the inflow jet produce changes in the mixing characteristics when different performance indexes are compared.

Expansión del regadío tradicional y control local en la Real Acequia de Moncada

Resumen. Son numerosos los ejemplos de sistemas de riego que han sido capaces de auto-gestionar el agua como un recurso comunal a largo plazo y en condiciones de marcada escasez, entre ellos el de la Comunidad de Regantes de la Real Acequia de Moncada (RAM), con 5000 ha y 13000 propietarios que gestionan de forma colectiva los recursos hidricos del rio Turia. Ostrom (1990), basandose en el caso de la Huerta de Valencia, propuso varios principios asociados al exito de la gestion comunal. El objetivo de este trabajo es revisar dos de ellos (a) la existencia de limites claramente definidos y (b) la capacidad de los usuarios de modificar las normas de operacion, para el caso de la RAM, basandonos en la consulta de archivos historicos. Los resultados muestran que, pese a que el espacio regado no ha permanecido totalmente constante, si que han existido unos limites prefijados que han permitido mantener una relacion entre tierra regable y disponibilidad de recursos que se ha adaptado a las necesidades de los usuarios y donde es destacable la importancia de la gestion y toma de decisiones a escala local. Palabras clave: riego, gestion colectiva, expansion del riego, derechos de riego, extremal. Abstract. There are wide arrays of examples of irrigation systems that have been able to self-manage water as a common resource in the long term and in severe scarcity conditions. One of them is the Real Acequia de Moncada (RAM) Irrigators Community, with 5000 ha and 13000 owners who collectively manage water resources from the Turia River. Ostrom (1990), based in the case of the Huerta of Valencia, proposed several principles associated to the success of collective management. The objective of this work is to analyze two of them for the case ofthe RAM, (a) the presence of clearly defined boundaries and (b) capacity of users to modify operational rules. We contrast these principles with the information of historical archives. We show that limits have existed, allowing maintaining a relation between irrigated land and resources, andadapting to users’ needs. Local management and decision making has been also of remarkable importance. Keywords: irrigation, collective management, irrigation expansion, water rights, extremal. doi: http://dx.doi.org/10.4995/ISL2014.2014.75

Factors Conditioning the Adoption of Water Conserving Techniques

In the Jucar River Basin (JRB), located in eastern Spain, there is significant of competition over water resources, were agricultural demand represents 80% of total demand. Desalinated and treated waste water are being integrated in water management. In addition, public policies aiming at conserving water have been implemented, mainly for the transformation from furrow to drip irrigation. In order to understand the process of adoption of drip irrigation technologies and its implications interviews were conducted to farmers and members of the management boards of two irrigation communities, the Acequia Real del Jucar (ARJ) and the Canal Jucar-Turia (CJT). Preliminary results show drip irrigation has led to a more centralized water management and to a technification of the irrigation staff. The adoption of water conserving technologies at IC level has been promoted by the existing water policies. However at field level, farmers assume the cost of implementing this technology. One of the significant reasons to adopt drip irrigation at plot level was to be obliged by the IC. In addition, the water price factor impact on farmers’ water use was mentioned to be less significant than the price of the harvest. Furthermore, a significant increase on the price would result on significant levels of abandonment.

Equity and Transparency: General Principles of the Success of Collective River and Ground Water Management in Valencia, Southeast Spain

This research focuses on nine irrigation communities situated in Valencia (Spain), where farmers have been working together for over a thousand years in order to create successful institutions for self-governance with regards to using scarce water from the Turia River.

Mathematical Model for Predicting and Estimating Evapotranspiration in Valencia Region, Spain

The Potential Evapotranspiration (ETo) is a powerful and useful tool in order to estimate and manage the amount of water that it is necessary for irrigating crops and trees. Several equations can be used for calculating ETo, although Penman-Monteith equation is the most accurate equation, function of the temperature, relative humidity, wind velocity and net radiation. Moreover, ETo is currently obtained from sparsely located weather stations around different zones or states. These values are often extrapolated for calculating the requirements within a zone or it is directly taken into account the nearest station from the crop. However, the limitations in the number of stations make sometimes that this procedure does not fit perfectly with the real water requirements of the plants. On the other hand, meteorology mathematical models for predicting weather behaviour have been developed over the last years based on basic fluid dynamics equations (Conservation of the mass, momentum and energy equations). Its usage has been validated in many studies for environmental and climatology studies. In the present paper, the authors have been used a mathematical model, RAMS, for evaluating the ETo around a wide zone, using the standard and homogeneous data in the Region of Valencia, Spain. The results show that this tool is a very powerful way to calculate ETo from sparsely stations. This ETo map has been obtained from a mathematical model, instead of extrapolating empirical values from the stations around a zone.