Water

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22 pages, 10460 KiB

Open AccessArticle

A Self-Contained and Automated Method for Flood Hazard Maps Prediction in Urban Areas

by Marco Sinagra, Carmelo Nasello, Tullio Tucciarelli, Silvia Barbetta, Christian Massari and Tommaso Moramarco

Water 2020, 12(5), 1266; https://doi.org/10.3390/w12051266 - 29 Apr 2020

Cited by 7 | Viewed by 3223

Abstract

Water depths and velocities predicted inside urban areas during severe storms are traditionally the final result of a chain of hydrologic and hydraulic models. The use of a single model embedding all the components of the rainfall–runoff transformation, including the flux concentration in [...] Read more.

Water depths and velocities predicted inside urban areas during severe storms are traditionally the final result of a chain of hydrologic and hydraulic models. The use of a single model embedding all the components of the rainfall–runoff transformation, including the flux concentration in the river network, can reduce the subjectivity and, as a consequence, the final uncertainty of the computed water depths and velocities. In the model construction, a crucial issue is the management of the topographic data. The information given by a Digital Elevation Model (DEM) available on a regular grid, as well as all the other elevation data provided by single points or contour lines, allow the creation of a Triangulated Irregular Network (TIN) based unstructured digital terrain model, which provides the spatial discretization for both the hydraulic and the hydrologic models. The procedure is split into four steps: (1) correction of the elevation z* measured in the nodes of a preliminary network connecting the edges with all the DEM cell centers; (2) the selection of a suitable hydrographic network where at least one edge of each node has a strictly descending elevation, (3) the generation of the computational mesh, whose edges include all the edges of the hydrographic network and also other lines following internal boundaries provided by roads or other infrastructures, and (4) the estimation of the elevation of the nodes of the computational mesh. A suitable rainfall–runoff transformation model is finally applied to each cell of the identified computational mesh. The proposed methodology is applied to the Sovara stream basin, in central Italy, for two flood events—one is used for parameter calibration and the other one for validation purpose. The comparison between the simulated and the observed flooded areas for the validation flood event shows a good reconstruction of the urban flooding. Full article

(This article belongs to the Special Issue Design of Urban Water Drainage Systems)

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17 pages, 8237 KiB

Open AccessArticle

Hydrological Modelling and Evaluation of Detention Ponds to Improve Urban Drainage System and Water Quality

by Fernanda Pereira Souza, Maria Elisa Leite Costa and Sergio Koide

Water 2019, 11(8), 1547; https://doi.org/10.3390/w11081547 - 26 Jul 2019

Cited by 24 | Viewed by 6318

Abstract

Paranoá Lake is an urban lake and it is being used as a source for urban water supply since last year. Until 1990, algal blooms occurred and improvements on wastewater treatment plants carried out improved the water quality very rapidly due to phosphorus [...] Read more.

Paranoá Lake is an urban lake and it is being used as a source for urban water supply since last year. Until 1990, algal blooms occurred and improvements on wastewater treatment plants carried out improved the water quality very rapidly due to phosphorus load reduction. Recently, water quality is deteriorating, which is probably due to diffuse pollution. In Brazil, we adopt separated pipe networks for sewage and stormwaters, although cross flows occur. The evaluation of urban drainage stormwaters entering the lake and proposition of technical alternatives is crucial in minimizing the impacts on lake water quality. Quantitative and qualitative behavior of urban stormwaters were analyzed by means of monitoring the runoff flows and pollutant concentrations. Mathematical modelling while using the Storm Water Management Model—SWMM was carried out, and good correlations were found for flow modelling. However, poor response was achieved for water quality simulations, affecting the simulated pollutant loads entering the lake. The simulation of 13 alternatives for detention ponds location was also evaluated, as well as their influences on flow damping capability. The detention ponds that were tested were placed in line in the drainage mains to study the effects of their location on the removal of pollutants. As expected, the results showed that ponds located near the outfall are more efficient in reducing flow peaks. However, this layout requires construction woks in areas that are more sensitive to environmental and urbanistic problems and with higher land commercial values. Alternatives with smaller volumes in public areas near the center of the catchment area can lead to the peak flow damping required by the existing drainage network to avoid overflows. In conclusion, detention ponds can be a good alternative for improving the stormwater quantity and quality, but also alternatives that promote increased infiltration, should also be considered for compensating the infiltration lost due to urbanization. Full article

(This article belongs to the Special Issue Design of Urban Water Drainage Systems)

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14 pages, 5368 KiB

Open AccessArticle

Effectiveness of Rainwater Harvesting Systems for Flood Reduction in Residential Urban Areas

by Gabriele Freni and Lorena Liuzzo

Water 2019, 11(7), 1389; https://doi.org/10.3390/w11071389 - 6 Jul 2019

Cited by 87 | Viewed by 20333

Abstract

Rainwater harvesting (RWH) systems have many benefits being an effective alternative water supply solution, not only in arid and semi-arid regions. Also, these systems can be useful in the reduction of flood risk in urban areas. Nevertheless, most of the studies in literature [...] Read more.

Rainwater harvesting (RWH) systems have many benefits being an effective alternative water supply solution, not only in arid and semi-arid regions. Also, these systems can be useful in the reduction of flood risk in urban areas. Nevertheless, most of the studies in literature focused on the potential of RWH in reducing water consumption, whereas few examples examined their efficiency in the retention of stormwater in flood-susceptible residential areas. The aim of this work was to investigate the reliability of RWH systems in terms of stormwater retention. Specifically, the performance of RWH tanks to supply water for toilet flushing, in more than 400 single-family houses in a residential area of Sicily (Southern Italy) was analyzed. The area of study was chosen due to its high susceptibility to flooding. A flushing water demand pattern was defined using water consumption data collected during a measurement campaign. The yield-after-spillage algorithm was used to simulate the daily water balance of the RWH tanks. The effect of the RWH implementation on flood volumes in the area of study was quantified using FLO-2D. Results point out that the potential of neighborhood RWH installation in the mitigation of flood risk is highly related to rainfall amount. Full article

(This article belongs to the Special Issue Design of Urban Water Drainage Systems)

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17 pages, 1948 KiB

Open AccessArticle

Hydrological Effectiveness of an Extensive Green Roof in Mediterranean Climate

by Stefania Anna Palermo, Michele Turco, Francesca Principato and Patrizia Piro

Water 2019, 11(7), 1378; https://doi.org/10.3390/w11071378 - 4 Jul 2019

Cited by 74 | Viewed by 6517

Abstract

In urban water management, green roofs provide a sustainable solution for flood risk mitigation. Numerous studies have investigated green roof hydrologic effectiveness and the parameters that influence their operation; many have been conducted on the pilot scale, whereas only some of these have [...] Read more.

In urban water management, green roofs provide a sustainable solution for flood risk mitigation. Numerous studies have investigated green roof hydrologic effectiveness and the parameters that influence their operation; many have been conducted on the pilot scale, whereas only some of these have been executed on full-scale rooftop installations. Several models have been developed, but only a few have investigated the influence of green roof physical parameters on performance. From this broader context, this paper presents the results of a monitoring analysis of an extensive green roof located at the University of Calabria, Italy, in the Mediterranean climate region. To obtain this goal, the subsurface runoff coefficient, peak flow reduction, peak flow lag-time, and time to the start of runoff were evaluated at an event scale by considering a set of data collected between October 2015 and September 2016 consisting of 62 storm events. The mean value of subsurface runoff was 32.0% when considering the whole dataset, and 50.4% for 35 rainfall events (principally major than 8.0 mm); these results indicate the good hydraulic performance of this specific green roof in a Mediterranean climate, which is in agreement with other studies. A modeling approach was used to evaluate the influence of the substrate depth on green roof retention. The soil hydraulics features were first measured using a simplified evaporation method, and then modeled using HYDRUS-1D software (PC-Progress s.r.o., Prague, Czech Republic) by considering different values of soil depth (6 cm, 9 cm, 12 cm, and 15 cm) for six months under Mediterranean climate conditions. The results showed how the specific soil substrate was able to achieve a runoff volume reduction ranging from 22% to 24% by increasing the soil depth. Full article

(This article belongs to the Special Issue Design of Urban Water Drainage Systems)

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18 pages, 4001 KiB

Open AccessArticle

Evaluating Curb Inlet Efficiency for Urban Drainage and Road Bioretention Facilities

by Xiaoning Li, Xing Fang, Gang Chen, Yongwei Gong, Jianlong Wang and Junqi Li

Water 2019, 11(4), 851; https://doi.org/10.3390/w11040851 - 23 Apr 2019

Cited by 14 | Viewed by 5066

Abstract

An updated two-dimensional flow simulation program, FullSWOF-ZG, which fully (Full) solves shallow water (SW) equations for overland flow (OF) and includes submodules modeling infiltration by zones (Z) and flow interception by grate-inlet (G), was tested with 20 locally depressed curb inlets to validate [...] Read more.

An updated two-dimensional flow simulation program, FullSWOF-ZG, which fully (Full) solves shallow water (SW) equations for overland flow (OF) and includes submodules modeling infiltration by zones (Z) and flow interception by grate-inlet (G), was tested with 20 locally depressed curb inlets to validate the inlet efficiency (E_ci), and with 80 undepressed curb inlets to validate the inlet lengths (L_T) for 100% interception. Previous curb inlet equations were based on certain theoretical approximations and limited experimental data. In this study, 1000 road-curb inlet modeling cases from the combinations of 10 longitudinal slopes (S₀, 0.1–1%), 10 cross slopes (S_x, 1.5–6%), and 10 upstream inflows (Q_in, 6–24 L/s) were established and modeled to determine L_T. The second 1000 modeling cases with the same 10 S₀ and 10 S_x and 10 curb inlet lengths (L_ci, 0.15–1.5 m) were established to determine E_ci. The L_T and E_ci regression equations were developed as a function of input parameters (S₀, S_x, and Q_in) and L_ci/L_T with the multiple linear regression method, respectively. Newly developed regression equations were applied to 10,000 inlet design cases (10 S₀, 10 S_x, 10 Q_in, and 10 L_ci combinations) and comprehensively compared with three equations in previous studies. The 100% intercepted gutter flow (Q_g₁₀₀) equations were derived, and over-prediction of Q_g₁₀₀ from previous methods was strongly correlated to smaller S₀. Newly developed equations gave more accurate estimations of L_T and E_ci over a wide range of input parameters. These equations can be applied to designing urban drainage and road bioretention facilities, since they were developed using a large number of simulation runs with diverse input parameters, but previous methods often overpredict the gutter flow of total interception when the longitudinal slope S₀ is small. Full article

(This article belongs to the Special Issue Design of Urban Water Drainage Systems)

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21 pages, 3466 KiB

Open AccessArticle

Measurement of Permeability and Comparison of Pavements

by Lu-Ming Chen, Jui-Wen Chen, Ting-Hao Chen, Timothy Lecher and Paul C. Davidson

Water 2019, 11(3), 444; https://doi.org/10.3390/w11030444 - 2 Mar 2019

Cited by 17 | Viewed by 10519

Abstract

Permeable pavements have the ability to reduce surface runoff by allowing water to infiltrate into the underlying soil. The potential of permeable pavements to assist in managing stormwater and improve water quality has gained attention as an option, other than conventional impermeable concrete [...] Read more.

Permeable pavements have the ability to reduce surface runoff by allowing water to infiltrate into the underlying soil. The potential of permeable pavements to assist in managing stormwater and improve water quality has gained attention as an option, other than conventional impermeable concrete for paving purposes. This study examined the permeability of three different pavement systems, including the JW Eco-technology pavement (JW), which has not previously been installed or studied in the U.S., standard impermeable concrete (IC), and pervious concrete (PC). Each pavement type was installed in triplicate. Devices based on the ASTM C1701/C1701M and ASTM C1781/C1781M constant-head methods, the National Center for Asphalt Technology (NCAT) falling-head permeameter, and two new square frames, SF-4 and SF-9, modified to fit the JW pavement, were utilized for permeability measurement on several locations of each pavement system. The results showed that the JW Eco-technology pavement had comparable permeability to the commonly used PC pavement in each method used. In addition, there was a strong correlation between the permeability measurements of NCAT method and SF-4, and between the ASTM standard and SF-9. The square frames used in this study showed their effectiveness and efficiency in performing permeability measurements. It was also found that the permeability obtained had a pronounced difference in values between the falling head and the constant head methods, with an average ratio ranging from 4.08–6.36. Full article

(This article belongs to the Special Issue Design of Urban Water Drainage Systems)

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14 pages, 2222 KiB

Open AccessArticle

Comprehensive Performance Evaluation System Based on Environmental and Economic Benefits for Optimal Allocation of LID Facilities

by Yiran Bai, Yuhong Li, Ruoyu Zhang, Na Zhao and Xiaofan Zeng

Water 2019, 11(2), 341; https://doi.org/10.3390/w11020341 - 18 Feb 2019

Cited by 45 | Viewed by 5117

Abstract

In recent years, urban flooding occurred frequently because of extreme rainstorms. Sponge city construction can effectively mitigate urban flooding and improve urban rainwater utilization. Low-impact development (LID) is regarded as a sustainable solution for urban stormwater management. In this project, a comprehensive evaluation [...] Read more.

In recent years, urban flooding occurred frequently because of extreme rainstorms. Sponge city construction can effectively mitigate urban flooding and improve urban rainwater utilization. Low-impact development (LID) is regarded as a sustainable solution for urban stormwater management. In this project, a comprehensive evaluation system was developed based on environmental and economic benefits using the analytical hierarchy process (AHP) and the Storm Water Management Model (SWMM) of the United States (US) Environmental Protection Agency (EPA). The performance of four LID scenarios with the same locations but different sizes of green roof, permeable pavement, concave greenbelt, and rain garden were analyzed in the Sucheng district of Jiangsu province in China. Results illustrate that the green roof performed best in reducing runoff, while the rain garden performed worst. The LID combination scenario (1) that contained more green roof, permeable pavement, and concave greenbelt facilities, but fewer rain gardens had the better comprehensive performance on the basis of environmental and economic benefits. The combined scenario (2) (LID proportion of maximum construction area was 40%) could also be an alternative. This study provides a guide to optimize LID layouts for sponge city construction, which can also provide optimal selection for other sponge city constructions. Full article

(This article belongs to the Special Issue Design of Urban Water Drainage Systems)

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17 pages, 4187 KiB

Open AccessArticle

A Data-Driven Surrogate Modelling Approach for Acceleration of Short-Term Simulations of a Dynamic Urban Drainage Simulator

by Mahmood Mahmoodian, Jairo Arturo Torres-Matallana, Ulrich Leopold, Georges Schutz and Francois H. L. R. Clemens

Water 2018, 10(12), 1849; https://doi.org/10.3390/w10121849 - 13 Dec 2018

Cited by 6 | Viewed by 3890

Abstract

In this study, applicability of a data-driven Gaussian Process Emulator (GPE) technique to develop a dynamic surrogate model for a computationally expensive urban drainage simulator is investigated. Considering rainfall time series as the main driving force is a challenge in this regard due [...] Read more.

In this study, applicability of a data-driven Gaussian Process Emulator (GPE) technique to develop a dynamic surrogate model for a computationally expensive urban drainage simulator is investigated. Considering rainfall time series as the main driving force is a challenge in this regard due to the high dimensionality problem. However, this problem can be less relevant when the focus is only on short-term simulations. The novelty of this research is the consideration of short-term rainfall time series as training parameters for the GPE. Rainfall intensity at each time step is counted as a separate parameter. A method to generate synthetic rainfall events for GPE training purposes is introduced as well. Here, an emulator is developed to predict the upcoming daily time series of the total wastewater volume in a storage tank and the corresponding Combined Sewer Overflow (CSO) volume. Nash-Sutcliffe Efficiency (NSE) and Volumetric Efficiency (VE) are calculated as emulation error indicators. For the case study herein, the emulator is able to speed up the simulations up to 380 times with a low accuracy cost for prediction of the total storage tank volume (medians of NSE = 0.96 and VE = 0.87). CSO events occurrence is detected in 82% of the cases, although with some considerable accuracy cost (medians of NSE = 0.76 and VE = 0.5). Applicability of the emulator for consecutive short-term simulations, based on real observed rainfall time series is also validated with a high accuracy (NSE = 0.97, VE = 0.89). Full article

(This article belongs to the Special Issue Design of Urban Water Drainage Systems)

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13 pages, 1882 KiB

Open AccessArticle

Effect of a Submerged Zone and Carbon Source on Nutrient and Metal Removal for Stormwater by Bioretention Cells

by Mo Wang, Dongqing Zhang, Yong Li, Qinghe Hou, Yuying Yu, Jinda Qi, Weicong Fu, Jianwen Dong and Yuning Cheng

Water 2018, 10(11), 1629; https://doi.org/10.3390/w10111629 - 12 Nov 2018

Cited by 40 | Viewed by 5556

Abstract

A bioretention system is a low-impact and sustainable treatment facility for treating urban stormwater runoff. To meet or maintain a consistently satisfactory performance, especially in terms of increasing nitrogen removal efficiency, the introduction of a submerged (anoxic) zone (SZ) combined with a module-based [...] Read more.

A bioretention system is a low-impact and sustainable treatment facility for treating urban stormwater runoff. To meet or maintain a consistently satisfactory performance, especially in terms of increasing nitrogen removal efficiency, the introduction of a submerged (anoxic) zone (SZ) combined with a module-based carbon source (C) has been recommended. This study investigated the removal of nitrogen (N), phosphorus (P) and heavy metals with a retrofitted bioretention system. A significant (p < 0.05) removal enhancement of N as well as total phosphorus (TP) was observed, in the mesocosms with additions of exogenous carbon as opposed to those without such condition. However, even in the mesocosm with SZ alone (without exogenous C), TP removal showed significant enhancement. With regard to the effects of SZ depth on nutrient removal, the results showed that the removal of both N and P in module with a shallow SZ (200 mm) showed significant enhancement compared to that in module with a deep SZ (300 mm). Removal efficiencies greater than 93% were observed for all three heavy metals tested (Cu, Pb, and Zn) in all mesocosms, even in the bioretention module without an SZ or plants, and it indicated that adsorption by the filtration media itself is probably the most important removal mechanism. Only Cu (but not Pb or Zn) showed significantly enhanced removal in module with an SZ as compared to those without an SZ. Carbon source played a minor role in metal removal as no significant (p > 0.05) improvement was observed in module with C as compared to that without C. Based on these results, the incorporation of SZ with C in stormwater biofilters is recommended. Full article

(This article belongs to the Special Issue Design of Urban Water Drainage Systems)

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14 pages, 2030 KiB

Open AccessArticle

The Influence of Geotextile Type and Position in a Porous Asphalt Pavement System on Pb (II) Removal from Stormwater

by Yao Zhao, Shuyu Zhou, Chen Zhao and Caterina Valeo

Water 2018, 10(9), 1205; https://doi.org/10.3390/w10091205 - 7 Sep 2018

Cited by 21 | Viewed by 4527

Abstract

Porous asphalt (PA) pavement systems with and without a geotextile layer were investigated in laboratory experiments to determine the impacts of the geotextile layer on the processes leading to lead ion (Pb²⁺) removal from stormwater runoff. Two types of geotextile membranes [...] Read more.

Porous asphalt (PA) pavement systems with and without a geotextile layer were investigated in laboratory experiments to determine the impacts of the geotextile layer on the processes leading to lead ion (Pb²⁺) removal from stormwater runoff. Two types of geotextile membranes that were placed separately at upper and lower levels within the PA systems were tested in an artificial rainfall experiment while using synthetic rainwater. The effect of storage capacity within the system on Pb²⁺ removal was also investigated. Results indicated that the use of a geotextile layer resulted in a longer delay to the onset of effluent. The non-woven geotextile membrane that was placed below the reservoir course improved the Pb²⁺ removal rate by 20% over the removal efficiency of the system while using a woven geotextile placed just below the surface but before the choker course. Pb²⁺ ions were reduced by over 98% in the effluent after being held for 24 h in reservoir storage. Results suggest that temporary storage of stormwater in the reservoir course of a PA system is essential to improving Pb²⁺ ion removal capability. Full article

(This article belongs to the Special Issue Design of Urban Water Drainage Systems)

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14 pages, 6424 KiB

Open AccessArticle

Clogging Impacts on Distribution Pipe Delivery of Street Runoff to an Infiltration Bed

by Min-Cheng Tu and Robert Traver

Water 2018, 10(8), 1045; https://doi.org/10.3390/w10081045 - 7 Aug 2018

Cited by 19 | Viewed by 4888

Abstract

The performance of flow through orifices on a perforated distribution pipe between periods with and without partial clogging (submersion of part of the distribution pipe) was compared. The distribution pipe receives runoff and delivers it to an underground infiltration bed. Clogging appeared in [...] Read more.

The performance of flow through orifices on a perforated distribution pipe between periods with and without partial clogging (submersion of part of the distribution pipe) was compared. The distribution pipe receives runoff and delivers it to an underground infiltration bed. Clogging appeared in winter but was reduced in summer. Performance of flow delivery was found to be defined by the effective pipe length and the pressure head. ANCOVA (ANalysis of COVAriance) was used to examine the clogging effect with flow rate plotted against the effective pipe length times the square root of the mean pressure head, and found that it was significant during low or no rainfall. During larger storms, clogging had little effect on pipe performance. Clogging might be caused by leaves and other trash accumulating in the lower section of the pipe in winter and its effect was insignificant when the water level rose in the pipe, utilizing significantly more orifices on the distribution pipe. Larger storms might also move the debris, thus exposing the orifices. The current maintenance schedule was sufficient to keep the distribution pipe at a satisfactory performance even though partial clogging can exist. Full article

(This article belongs to the Special Issue Design of Urban Water Drainage Systems)

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13 pages, 3134 KiB

Open AccessArticle

The Testing of Standard and Recyclable Filter Media to Eliminate Hydrogen Sulphide from Sewerage Systems

by Petr Hluštík and Jiří Novotný

Water 2018, 10(6), 689; https://doi.org/10.3390/w10060689 - 25 May 2018

Cited by 7 | Viewed by 7624

Abstract

This article focuses on the subject of odours forming in sewage transfer chambers with displacement inlets, as well as the odours in their vicinity. It further covers the locations of odour formation, factors influencing the formation of hydrogen sulphide in wastewater, methods of [...] Read more.

This article focuses on the subject of odours forming in sewage transfer chambers with displacement inlets, as well as the odours in their vicinity. It further covers the locations of odour formation, factors influencing the formation of hydrogen sulphide in wastewater, methods of removing hydrogen sulphide from wastewater, and laboratory testing of filtration media efficacy at various concentration levels of H₂S. The laboratory testing of filtration media efficacy is performed for products normally used by sewerage system operators guaranteeing the elimination of hydrogen sulphide (activated carbon, natural minerals and gels), recyclable materials (paper) and secondary raw materials in the field of waste management (biochar—the final product of microwave pyrolysis). Odour generated by sewerage systems is a secondary issue faced by all sewerage system operators, who sustain considerable expense in corrective measures to address this problem. The most economical and widespread measure used by those operators is hydrogen sulphide removal by filtration (filtration materials). Filtration media are installed in special cartridges under sewage covers in locations where the irritating odour is formed. These filtration cartridges, designed solely to eliminate odour from the surroundings, show various degrees of efficacy in removing H₂S. Full article

(This article belongs to the Special Issue Design of Urban Water Drainage Systems)

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