Methodology to quantify clogging coefficients for grated inlets: application to SANT MARTI catchment (Barcelona)

This is the accepted version of the following article: Gómez, M, Parés, J, Russo, B, Martínez‐Gomariz, E. Methodology to quantify clogging coefficients for grated inlets. Application to SANT MARTI catchment (Barcelona). J Flood Risk Management. 2019; 12:e12479. https://doi.org/10.1111/jfr3.12479, which has been published in final form at https://onlinelibrary.wiley.com/doi/10.1111/jfr3.12479.Within the drainage system of a city, the set of inlets is in charge of taking the runoff produced by local storms to the stormwater/sewer. In the drainage system design the selection of appropriate inlet models and their location is one of the fundamental aspects. The hydraulics of these inlets has received great attention within the last years; however, few inlet makers provide the hydraulic capacity of their products. In addition, these data usually consider clean water, while in reality, numerous inlets can be either totally or partially clogged. This aspect should be kept in mind within the design process. In this paper, a methodology to consider the hydraulic effects of clogging phenomena is presented. The work started from a visual inspection of the grated inlets throughout the urban catchment of Sant Martí, Barcelona, as a means of identifying clogging patterns, their repetitive forms and their associated frequency. After that, clogged patterns were reproduced in laboratory testing of typical inlets types, thereby obtaining the real quantity of water that could be captured by each of them. It was shown that the same expression employed to describe the efficiency of clean inlets can be used to assess the efficiency of those clogged. A reduction factor in terms of hydraulic capacity and related to each clogging pattern has been defined for use in hydraulic studies of runoff along streets. Finally, the paper compares the obtained results in terms of clogging coefficient with another experimental campaign carried out in other catchment of the city.Peer ReviewedPostprint (author's final draft

Assessment of inlet efficiency through a 3D simulation: numerical and experimental comparison

Inlet efficiency is a requirement for characterizing the flow transfers between surface and sewer flow during rain events. The dual drainage approach is based on the joint analysis of both upper and lower drainage levels, and the flow transfer is one of the relevant elements to define properly this joint behaviour. This paper presents the results of an experimental and numerical investigation about the inlet efficiency definition. A full scale (1:1) test platform located in the Technical University of Catalonia (UPC) reproduces both the runoff process in streets and the water entering the inlet. Data from tests performed on this platform allow the inlet efficiency to be estimated as a function of significant hydraulic and geometrical parameters. A reproduction of these tests through a numerical three-dimensional code (Flow-3D) has been carried out simulating this type of flow by solving the RANS equations. The aim of the work was to reproduce the hydraulic performance of a previously tested grated inlet under several flow and geometric conditions using Flow-3D as a virtual laboratory. This will allow inlet efficiencies to be obtained without previous experimental tests. Moreover, the 3D model allows a better understanding of the hydraulics of the flow interception and the flow patterns approaching the inlet.Preprin

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

This is an Accepted Manuscript of an article published by Taylor & Francis Group in Urban water journal on 2017, available online at: http://www.tandfonline.com/doi/full/10.1080/1573062X.2017.1301501A 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.Peer ReviewedPostprint (author's final draft

New offset-free method for model predictive control of open channels

Irrigation or drainage canals can be controlled by model predictive control (MPC). Applying MPC with an internal model in the presence of unknown disturbances in some cases can lead to steady state offset. Therefore an additional component should be implemented along with the MPC. A new method eliminating the offset has been developed in this paper for MPC. It is based on combining two basic approaches of MPC. It has been implemented to control water levels in the three-pool UPC laboratory canal and further numerically tested using a test case benchmark proposed by the American Society of Civil Engineers (ASCE). It has been found that the developed offset-free method is able to eliminate the steady-state offset, while taking into account known and unknown disturbances.Peer ReviewedPostprint (author's final draft

Toward sustainable management: 2D modelling of a self-cleaning system to improve geometry in front of the flushing gate

This paper aims to show how numerical modelling based on 2D SWE can be used to analyze the cleaning effectiveness of flushing waves in storm tanks. The case study under consideration is an existing storm tank located in Badalona, a municipality of Barcelona, Spain. Storm tank cleaning systems are critical features that must be carefully addressed. If not appropriately addressed, operation and maintenance work costs can drastically increase. There are numerous currently available technologies for cleaning storage tanks. However, no specific guide on this field has been identified. References are provided by the manufacturers through their commercial catalogues. Generally, this information is not based on experimental or numerical experiences or results have not been published in the literature of scientific papers. In this study, a public domain software (IBER) was used to develop 2D hydraulic analysis of the selected tank. The results obtained show how the phenomenon of recirculation is acting in some areas of the lane. This implies a dissipation of energy, thus causing difficulties in terms of cleaning procedures. Furthermore, two new scenarios have been tested to determine how a different lane width might affect hydrodynamic behavior. A newly suggested geometry for the existing lane of the tank is proposed by using the numerical modeling software. The proposed geometry in the current pilot tank achieves higher velocities and avoids recirculation areas. The results demonstrate that numerical modelling of these types of processes is possible with the computer models available (commercial codes) and can be used to optimize cleaning system designPeer ReviewedPostprint (published version

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

The final publication is available at Springer via http://dx.doi.org/10.1007/s11069-016-2242-zPopulations 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.Peer ReviewedPostprint (author's final draft

Application of the KINEROS 2 model to natural basin for estimation of erosion

This study compares different methods to calculate erosion and sedimentation processes in the Aviar Basin, a natural peri-urban basin located in Comúd’Encamp (Andorra). The basin area is small, covering less than one square kilometer. Currently, increased densities of houses and buildings under natural basins can cause drainage problems. This is due to the heavy accumulation of eroded solid material in the sewer systems. Therefore, for a given basin condition, accurate estimation of erosion and sedimentation amounts is important. The development of erosion models aims to facilitate the estimation of eroded solid material and the design of possible protective measures to prevent soil losses. Both empirical and physically based erosion models were used to study the Aviar Basin for these purposes. Empirical models include USLE (Universal Soil Loss Equation), RUSLE (Revised USLE) and MUSLE (Modified USLE), while one physically based model, KINEROS 2, was used. The volumes of solid materials produced in the Aviar Basin during the year 2012 were determined using these four different erosion models and then compared between them. The results of this study show that the estimation of soil loss using KINEROS 2 is useful in practice because the results obtained are close to those obtained from the empirical models.Peer ReviewedPostprint (published version

An approach to the modelling of stability of waste containers during urban flooding

This is the accepted version of the following article: Martínez‐Gomariz, E, Russo, B, Gómez, M, Plumed, A. An approach to the modelling of stability of waste containers during urban flooding. J Flood Risk Management. 2020; 13 ( Suppl. 1):e12558. https://doi.org/10.1111/jfr3.12558, which has been published in final form at https://onlinelibrary.wiley.com/doi/full/10.1111/jfr3.12558.Before the solid waste is dumped in landfills, the collection process for large Spanish cities starts from a regular collection of household waste municipal service which is carried out through street containers. When an urban flood occurs those containers may lose their stability, thereby allowing debris (i.e., solid waste contained) and leachate to escape from the container and contaminate the flood water. Moreover, once a container loses its stability it can further constrict a narrow street and increase flooding, thereby creating a closed basin with no outlet for runoff and exacerbating the effects of flooding. Therefore, the waste containers stability when exposed to flooding is definitely an environmental, safety and health concern to be addressed. In this research stability functions for waste containers exposed to urban floods have been derived. These thresholds have been employed to analyse the containers' potential behaviour during floods in Barcelona. In order to validate the model a historical rainfall has been modelled and low-return-period design storms (i.e., 1, 5, and 10 years) have been used to assess the containers vulnerability against floods for frequent rainfall events. Once the number of potentially unstable containers has been estimated, an adaptation measure has been proposed in order to increase the resilience of waste sector against urban floods in Barcelona.Peer ReviewedPostprint (author's final draft

Physically and chemically modified starches as texturisers of low-fat milk gels

In reduced fat-milk gels lack of fat globules results in undesirable texture changes. This study evaluates application of chemically modified (E-1412,E-1414,E-1422,E-1442), pregelatinized, and both pregelatinized (PG) and chemically modified (PGE-1414) starches as fat replacers. Skimmed milk was substituted with 2% of each starch. The pH and rheological evolution during the acidification process, viscosity of the stirred gels, texture of the set gels and syneresis of all gels were measured. Skimmed and full-fat milk gels were included as controls. All starches had lower or higher pH values, than skimmed or full fat milk gels during acidification. Gelation time was reduced for all starches compared to the skimmed milk gel. For both stirred and set milk gels, with PG, PGE-1414, E-1422 and E-1442 had viscosity/texture values similar or higher to those found for full fat milk gel. For syneresis, E-1412 had drastically increased values when compared with both controls.  Spanish Ministry of Economy and Competitiveness (Project AGL2014-52928-C2)European Regional Development Fund (FEDER

Quantification of energy loss in two grated inlets under pressure

Grated inlets have the normal function of collecting the surface runoff into sewer networks, but when the flow exceeds the capacity of the sewer pipes and conduits get pressurized, an outflow from the sewer manholes and grates can occur. In this case, the grate produces an energy loss in the outflow from sewer to street that could be hydraulically quantified characterizing this kind of flow. Energy loss analysis in trash racks can be found in technical literature, but no specific studies on sewer grate inlets have been found. For this reason, some experiments in full scale were developed in the hydraulic laboratory of the Technical University of Catalonia (UPC) in order to quantify hydraulic energy losses associated with flow through grated inlets during surcharging conditions. The main goal of this research work was to experimentally quantify the values of the local loss coefficient k for two different surcharged real scale grated inlets existing in Barcelona. For the tested overflows between 20 and 50 L/s, a range from 0.25 to 3.41 was observed for k coefficients under different average velocities of reference and different flow conditions.Peer ReviewedPostprint (published version