Beniamino Russo

Experimental study of the stability of pedestrians exposed to urban pluvial flooding

Abstract Populations in urban environments are extremely mobile throughout the day and in various weather conditions; accounting for this pedestrian mobility and security becomes high importance. Research into the security and stability of the pedestrian environment under exposure to critical water flows provides an essential knowledge base with which the associated hazard unto them can be critically evaluated. This research seeks to analyse degrees of hazard in relation to persons exposed to high-volume rain events in urban areas. Several human trials of critical urban flows were conducted in order to determine the stability limits of pedestrians, crossing through a water flow in a real-scale physic model. Additionally, the critical first step from a dry footpath into fast-flowing water is considered and an assessment of the tested subjects’ emotional responses when entering and crossing flooded roadways was carried out. Results from this study are compared with various proposed human stability criteria as well as alternatives proposed in other written works. The presented study offers a stability threshold focused on shallow depths and high-velocity conditions, the most common urban flooding conditions.

Methodology to Estimate the Hydraulic Efficiency of Nontested Continuous Transverse Grates

The aim of this paper is to improve and complete the results presented in a previous work published on this journal about an experimental campaign focused on the hydraulic efficiency of continuous transverse grates for draining paved areas. This type of surface drainage structure is commonly used in urban or impervious areas (public squares, airport pavements, parks, and pedestrian areas), where conventional inlets are not recommended because they are rendered ineffective by the lack of a well-defined channelized flow path and gradients capable of directing flows toward the collecting hydraulic structures. In this paper, a methodology is presented to estimate the hydraulic efficiency of nontested continuous transverse grates. Empirical expressions are proposed to relate grate hydraulic performance to flow parameters and grate geometry without the need for laboratory tests. Moreover, the spectrum of the grates was extended in terms of dimensions and hydraulic design with respect to the first study, to enlarge the range of validity of the proposed empirical expressions.

Stability criteria for flooded vehicles: a state‐of‐the‐art review

Hazard conditions related to vehicular circulation are important in flood risk management. The knowledge of vehicles stability when those are exposed to flooding is crucial for an informed flood risk management in urban areas. After losing stability, the vehicle becomes buoyant and may be washed away with potential injuries and fatalities. Therefore, the analysis of the stability of vehicles exposed to flooding is important in order to make decisions to reduce the damages and hazards. Herein a comprehensive state-of-the-art on stability of vehicles exposed to flooding is presented. The different studies have been gathered in experimental, theoretical and guidelines proposals and all of them focusing on parked vehicles. There is a clear need to conduct more research in this field by testing a greater variety of models in order to offer a more general methodology to define stability threshold for any vehicle exposed to flooding. Nevertheless, in this work, it has been demonstrate that the most safety stability criterion for vehicles exposed to flooding up to now is the proposed in the Guide AR&R.

Flood damage assessment in urban areas. Application to the Raval district of Barcelona using synthetic depth damage curves

This paper presents a detailed flood damage assessment in the Raval district of Barcelona. The implementation of a new 1D-2D coupled model is used to obtain flood depths, and new stage damage curves are developed to estimate the direct tangible damages. The curves have been validated using data from surveys and actual reported damages to the Spanish re-assurance. Finally, combining hazard and vulnerability levels by using a GIS-based toolbox, the expected annual damage of the area is obtained. This enables the determination of the critical points of the district in terms of flooding impacts, and highlights the need to implement strategies to cope with these impacts.

Experimental campaign to determine grated inlet clogging factors in an urban catchment of Barcelona

Urban drainage systems have two different drainage layers, one superficial and another underground, that are connected through drain inlets and manholes. Specifically, a collection system is formed by inlets distributed throughout a basin, with the function of collecting and directing the surface runoff into sewers. Generally, the hydraulic characterisation of the inlet system considers the grates in an ideal state, free of dirt and debris obstructions, although often this is not the case. In these cases, clogging effects should be considered as a reduction in terms of hydraulic efficiency. The aim of this paper is to present a methodology to determine, quantitatively, the hydraulic efficiency reduction of partially clogged grated inlets. With this aim, clogging patterns for the most common grated inlets operating in Barcelona (Spain) were defined and experimental tests at real scale were carried out in order to determine the hydraulic efficiency reduction due to clogging phenomena.

A new experiments-based methodology to define the stability threshold for any vehicle exposed to flooding

Abstract A vehicle exposed to flooding, after losing stability, becomes buoyant and may be washed away with potential injuries and fatalities. Such vehicles cause additional disruption to traffic that is already affected by flooding, which may lead to substantial indirect economic impact, especially in urban areas. Therefore, the analysis of the stability of vehicles exposed to flooding is important in order to make decisions to reduce damages and hazards. In this research, based on an experimental campaign that included a range of twelve car models, a new methodology to obtain the stability threshold for any real vehicle exposed to flooding is developed. A stability coefficient (SCmod) is derived with which the vehicles can be sorted by stability against water flows and their stability functions may be determined. The experiments were conducted with three different model scales (1:14, 1:18 and 1:24) and involved analysis of both friction and buoyancy effects, which made this the most comprehensive research study to date. This methodology enables the definition of a stable area in the flow depth-velocity domain for any real vehicle. A tool is provided that decision-makers in the field of urban flood risk management can employ and after defining a design vehicle they can obtain its corresponding stability threshold.

Assessment of the Ability of a Volume of Fluid Model to Reproduce the Efficiency of a Continuous Transverse Gully with Grate

This paper deals with the numerical investigation of the drainage efficiency of a continuous transverse gully with the grate’s slots aligned in the flow direction and compared with experimental data sets. The gully efficiency attained with a three-dimensional (3D) numerical model is compared and validated against experimental data. The numerical simulations are performed using a computational fluid dynamics volume of fluid solver. Different slopes, from 0 to 10%, and a wide range of drainage flows, from 6.67 to 66.67??L/s/m66.67??L/s/m, are simulated. The linear relation between Froude number and efficiency of the gully is in agreement to the one experimentally obtained.

Experimental and Numerical Study of Stability of Vehicles Exposed to Flooding

Hazard conditions related to cars in urban areas circulation are important in flood riskmanagement. The definition of stability conditions for vehicles when they are in rban areas during flood events is extremely relevant in the hazard and risk studies related to floods. When we test the stability of a car, the vehicle can be buoyant and may be swept away creating potential injuries and even casualties. In this document a description and presentation of results of an experimental campaign developed at the UPC laboratory in Barcelona is presented. For all the cars tested it is possible to define their specific stability limits that can be used by municipalities in their hazard and risk studies. Moreover, same process has been repeated but in a numerical way, with a 3D commercial code (Flow3D). The results obtained showed the possibilities of 3D numerical model to complement physical tests as a virtual lab, with the only drawback of the high computational time, several days to reproduce few seconds of real time.

Assessment of the effectiveness of structural and non‐structural measures to cope with global change impacts in Barcelona

In a context of high uncertainty of hydro-climatic variables, the development of updated methods to assess climate change impacts is as important as the provision of improved climate change data. This article presents the impacts of climate change on the flooding problems concerning a critical area of Barcelona and the assessment of the effectiveness of structural and nonstructural measures to cope with such impacts. For this purpose, a specific study tackling climate change influence on extreme precipitation in Barcelona and a detailed 1D/2Dcoupled model were used. Once the model was developed and calibrated, several scenarios of adaptation measures were considered to cope with climate change effects for the 2050 horizon. Results concerning these scenarios were compared to a defined ‘business as usual scenario’. Climate change impacts were assessed in terms of flood hazard and risk maps concerning vehicular and pedestrian circulation for several return periods (1, 10 and 100 years) for all the considered scenarios. Additionally, direct tangible damages were estimated using depth-damage curves. The expected annual damage of the area is obtained by combining hazard and vulnerability levels using a Geographic Information System-based toolbox. By undertaking a cost-benefit analysis, the effectiveness of the strategies is assessed.