RIBAGUA-Revista Iberoamericana del Agua最新文献

Se describe la recuperación ambiental de un río urbano y torrencial que cruza el área metropolitana de Barcelona. Se repasa su historia, problemas ambientales, limitaciones de la restauración, diseño morfodinámico, estudios técnicos en modelo físico y de transporte sólido, aspectos sociales, y se hace una evaluación de la intervención doce años después de realizada.

The paper describes the environmental restoration of a torrential urban river flowing through the metropolitan area of Barcelona (Spain). An overview of the river history, environmental problems, constraints for the restoration, morphodynamical design, technical studies in a physical model, sediment transport and social aspects are presented. The restoration is assessed twelve years after its completion.

Regulating siphons present important advantages when the discharge capacity of a dam needs to be augmented. In addition to the increase of discharge capacity other advantages include: the lack of effects on the operating conditions; no modification is needed to the normal maximum level or spill level; and it is possible to design a discharge rule for the siphon as appropriate.

Furthermore, it is possible for these siphons to begin discharging before the reservoir level reaches the threshold discharge level with the possibility of reducing the reservoir level before arrival of a flood event, thus improving the flood attenuation. In this paper the operation of a siphon to start working before the reservoir reaches the discharge threshold is described, as well as, how to limit the risk of operational error. Finally, an example of the effectiveness of these siphons is given.

This article summarizes the main advances made by our group in the study of flow and substance transport dynamics in the Río de la Plata, based on the implementation of various models (RMA, MOHID, MARS) and incorporating existing high-quality field information. In the Río de la Plata, the main forcings that influence water circulation are flow discharge from its tributaries, tide waves (astronomic and meteorologic), and winds. There is a clear difference between the inner-middle region and the outer region of the Río de la Plata. The division between these two regions is known as the frontal region, where there is considerable widening of the section and an increase in depth. Because of these characteristics, the salinity field coming from the Atlantic Ocean reaches this region, with greater intensity in the deep regions where the saline stratification is more pronounced. This in turn gives the residual velocities in the middle region the typical two-dimensional characteristics of a flow discharge (net transport toward the outer region), while the residual flow in the outer region shows more complex, three-dimensional characteristics, with mainly incoming flow toward the continent in the deep areas and flow discharge mainly through the shallow coastal areas. There is an area of almost nil residual current in the frontal region. In addition to this clear spacial difference in the behavior of the body of the water, the meteorological conditions have a determining influence. The present study discusses diverse behaviors of the currents, salinity and fine sediment dynamics under calm and storm conditions.

In this study, the distributed hydrological and sedimentological model TETIS was applied in the Ésera River catchment (Spain). The aim of this study was to analyze the effect of Climate Change on the sediment dynamics in the catchment and the siltation of Barasona reservoir that drains it. The implementation of the sediment sub-model was performed using the volumes of sediment deposited in the reservoir and measured from three historical bathymetries as reference. To analyze the effects of Climate Change, the precipitation and temperature series obtained from the PRUDENCE project, for the current and future A2 and B2 climate scenarios have been used as model inputs. From the results of the simulations with TETIS, it can be concluded that the flow discharges tend to decrease in the future as a direct result of reduced precipitation, increased potential evapotranspiration and reduced soil moisture within the catchment. Despite the trend towards more torrential rainfall, model results indicate that floods will also tend to decrease, more markedly for the A2 scenario than for the B2 scenario, due to the large decrease in soil moisture already mentioned. Moreover, sediment transport tends to decrease for the A2 and increase for the B2 scenario. This situation is reflected in the siltation rates of Barasona reservoir, wherein for B2 no substantial changes are expected, as compared to the situation of the current climate condition, whereas for the A2 scenario a significantly longer service life is expected.

Gravity currents are flows generated by horizontal pressure gradients resulting from the effect of gravity on fluids of different density. When they occur in nature, gravity currents have a strong nonlinear behavior and have a wide range of temporal and spatial scales. In addition, the rotation of the earth raises the level of complexity of gravity currents due to the effect of the Coriolis force. This work addresses rotating gravity currents in planar geometry by direct numerical simulation (DNS). The simulations allow for a detailed analysis of the flow development, macroscopic parameters of the flow and turbulence structure. Simulations were performed using a pseudospectral code that uses Fourier expansions in the two horizontal directions and Chebyshev expansions in the vertical direction. This work documents in detail the code developed and the validation performed by comparing a simulation with experimental observations and theoretical predictions. This work also reports on two simulations with different rotation speeds. It was found that the flow rotation restricts the development of the current in the propagating direction, and induces oscillations in the front position. The frequency of these oscillations varies linearly with the rotation speed. Finally, this work also reports on Kelvin-Helmholtz-like turbulent structures at the front of the current produced by the rotation of the system.