1,720,983 research outputs found
Modelling physical and ecological processes in medium-to-large deep European perialpine lakes: directions of past research and issues to address for the future
No full textDeep intrusions of tributaries are suppressed for increasing winter residual stratification in deep oligomictic perialpine lakes south of the Alps
No full textHydrodynamics of a bordered collar as a countermeasure against pier scouring: Hydrodynamics countermeasure scouring
No full textAn experimental campaign on long-term clear-water scour at bridge piers with different configurations was performed in a laboratory to investigate the effects of different countermeasures. Tests were performed in a flume with a movable sediment bed for an unprotected cylindrical pier, a cylindrical pier with a standard collar and a cylindrical pier with a bordered collar. The scoured beds at the equilibrium stage were acquired through the photogrammetry technique and the efficiencies of the tested countermeasures were measured. Results showed a reduction in the maximum scour depth as well as in the scour hole volume with respect to the unprotected pier. The maximum scour depth was reduced by 59.63% with the standard collar and by 63.51% with the bordered collar. The scoured volume was reduced by 43.80% with the standard collar and by 60.00% with the bordered collar. The three-dimensional Reynolds-averaged Navier-Stokes equations were solved numerically to reproduce the hydrodynamics of the experiments. The volume of fluid technique was used to reproduce the free surface. For each test, the results of the simulations were analysed to investigate the flow field around the pier both at the initial (flat-bed) and at the equilibrium stages, highlighting the changes in the velocity field owing to the presence of the standard collar and of the bordered collar
Modelling physical and ecological processes in medium-to-large deep European perialpine lakes: A review
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A complete methodology to assess hydraulic risk in small ungauged catchments based on HEC-RAS 2D Rain-On-Grid simulations
No full textThis paper explores the use of the rain-on-grid (or direct rainfall) method for flood risk assessment at a basin scale. The method is particularly useful for rural catchments with small vertical variations and complex interactions with man-made obstacles and structures, which may be oversimplified by traditional hydrologically based estimations. The use of a hydrodynamic model solving mass and momentum conservation equations allows the simulation of runoff over the watershed at a basin scale. As a drawback, more detailed and spatially distributed data are needed, and the computational time is extended. On the other hand, a smaller number of parameters is needed compared to a hydrological model. Roughness and rainfall loss coefficients need to be calibrated only. The direct rainfall methodology was here implemented within the two-dimensional HEC-RAS model for the low-land rural, and ungauged, watershed of the Terdoppio River, Northern Italy. The resulting hydrographs at the closing section of the watershed were compared to synthetic design hydrographs evaluated through pure hydrological modelling, showing agreement on the peak discharge values for the low-probability scenarios, but not on the total volumes. The results in terms of water depth and flow velocity maps were used to create flood hazard maps using the Australian Institute for Disaster Resilience methodology. The Index of Proportional Risk model was then adopted to generate a basin-scale flood risk map, by combining flood hazard maps, damage functions for different building-use classes, and the value of reconstruction and content per unit area
Using ecohydrological regionalisation to estimate long term series of total nutrient loads flowing into Lake Como from institutional discrete monitoring data
No full textTwo decades of limnological investigation on Lake Como: field data analysis and ecosystem modeling
No full textPossible effects of climate change on the mixing regime of Lake Maggiore and implications for its water quality
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