LBM method for roughness effect in open channel flows

In this workwe present an enhancement of a free-surface Lattice Boltzmannmethod to evaluate pressure losses and wall roughness effects. Recent works in literature propose strategies to account for wall roughness, but mainly in small-scale computational domains, [1,2] or by means of a 2D approach, [3]. In the frame of 2D analyses, friction term has been defined in the shallow water problem as a function of slope of the bottom of the domain, roughness and water depth, [4]. In this work, three different strategies are proposed to account for wall roughness: a Smagorinsky-based approach, with an ad-hoc function to vary turbulent viscosity with the distance from the wall, an implementation of a partial-slip wall boundary collision and the simulation of roughness effects by means of an external force field, accounted for in the collision phase. © 2012 American Institute of Physics

Coping with extreme events. Effect of different reservoir operation strategies on flood inundation maps

The need of addressing "residual flood risk" associated with structural protection measures, such as levee systems and flood-control reservoirs, has fostered actions aimed at increasing flood risk awareness. Structural measures have lowered risk perception by inducing a false sense of safety. As a result, these structures contribute to an underestimation of the "residual risk". We analyze the effect of different reservoir operations, such as coping with drought versus coping with flood events, on flood inundation patterns. First, a hydrological model simulates different scenarios, which represent the dam regulation strategies. Each regulation strategy is the combination of an opening of the outlet gate and of the initial water level in the reservoir. Second, the corresponding outputs of the dam in terms of maximum discharge values are estimated. Then, in turn, each output of the dam is used as an upstream boundary condition of a hydraulic model used to simulate the flood propagation and the inundation processes in the river reach. The hydraulic model is thus used to determine the effect, in terms of inundated areas, of each dam regulation scenario. Finally, the ensemble of all flood inundation maps is built to define the areas more prone to be flooded. The test site is the Casanuova dam (Umbria, central Italy) which aims at: (i) mitigating floods occurring at the Chiascio River, one of the main tributaries of Tiber River, while (ii) providing water supply for irrigation. Because of these two competitive interests, the understanding of different scenarios generated by the dam operations offers an unique support to flood mitigation strategies. Results can lead to draw interesting remarks for a wide number of case studies

Using choice experiments to assess environmental impacts of dams in Portugal

Despite their well-known benefits in electricity production, dams are also responsible for some adverse environmental impacts affecting particularly the wellbeing of residents of the local communities. These environmental damages have not been included in the cost-benefit analysis of hydropower developments mainly because of the difficulty to determine their value. The prime objective of this paper is to measure the economic values of several environmental impacts due to the dams’ activity in Portugal, using a discrete choice experiments approach. With the results of this research paper, we expect to contribute to a more efficient and thorough cost-benefit analysis within the complex process of deciding the optimal location of future dams to be built not only in Portugal, but elsewhere. The addition of this stage to the decision-making process allows the integration of economic, social and environmental dimensions, promoting a richer and more informed decision processFinancial support from PTDC/EGE-ECO/122402/2010 is greatly appreciated