Urban Drainage Management Research Articles

Fully automated simplification of urban drainage models on a city scale

ABSTRACT The article presents an innovative method for simplifying urban drainage models. This approach strategically reduces complexity while preserving accuracy in large-scale, high-resolution models such as those of the city of Graz. It involves the selective removal and aggregation of sewer network elements like subcatchments and conduits, ensuring vital features like storage nodes and flow controls remain intact for precise simulations. Despite significant reductions in model components, the simplified version maintains high accuracy in hydrological and hydraulic aspects, including water balance components like infiltration loss, surface runoff, and external outflow. The method proves equally effective across both land cover and sewer shed-based models, offering computational efficiencies that speed-up processing by 20–45 times for the study site. This is particularly beneficial for rapid decision-making and resource optimization in urban planning. The model also adeptly predicts flood events, especially from larger, infrequent rainfall, although an overly restrictive flow capacity can refine flood predictions at the expense of other flow characteristics. Ultimately, this streamlined approach allows for the quick creation of simplified, yet accurate, models from high-resolution city-scale hydrodynamic data or digital twins, facilitating efficient and timely analyses in urban drainage management.

Stormwater Management in Urban Coastal Areas—A Review

Stormwater management in coastal urban cities, where drainage networks are influenced by marine dynamics and specific soil and altimetry conditions, has specific challenges that need to be addressed to ensure adequate management in such areas, which are also heavily affected by floods. Their location downstream of drainage basins and the interaction of network outfalls with current and tidal variability increases the vulnerability of populations and should therefore be the target of specific studies. This article presents a literature review, where publications that focus on stormwater management in coastal urban areas were identified and analyzed. The main objective was to present the key issues related to drainage in coastal areas, the most relevant challenges, the solutions and strategies that reveal the greater potential for application and the challenges for modeling this type of case. It is intended to provide a grounded basis for new ways of optimizing stormwater drainage in coastal areas and promote a sustainable urban water cycle. This review reveals the necessity to implement a multidisciplinary approach to minimize three main issues: urban flooding, stormwater pollution and groundwater salinization, including the adaptation of existing infrastructures, complementing them with control solutions at source, correct urban planning and the involvement of populations. For an effective management of urban stormwater drainage in coastal areas, this approach must be carried out on a watershed scale, duly supported by reliable decision support tools and monitoring systems.

Fluvial adjustments due to straightening and inadequate management of urban drainage: the Maringá Stream catchment, Southern Brazil

The morphological channel changes can occur through direct interventions, such as engineering works, or indirectly due to alterations in the catchment runoff. This study conducted morphometric evaluations using geoprocessing techniques and fieldwork in fluvial reaches altered by straightening and influenced by urbanization in the Maringá Stream catchment, located in the northern state of Paraná, Brazil. The study analyzed the sinuosity index and the average width of three representative reaches between the years 1970 and 2017. The sinuous morphology of the reaches was straightened in the 1970s and 1980s and did not re-establish itself. Over the past two decades, these reaches exhibited a trend of increasing average width (~100%) due to urbanization in the drainage areas. However, intermittent periods of channel narrowing were also observed. This behavior is associated with bank erosion and failure, leading to the formation of benches. The morphogenesis of this relief unit in the channel results from inadequate management of stormwater runoff from urban areas. This scenario indicates the need for coordinated efforts between urban stormwater management and fluvial geomorphology to maintain the physical integrity of rivers.

Identification of illicit discharges in sewer networks by an SWMM-Bayesian coupled approach.

Illicit discharges into sewer systems are a widespread concern within China's urban drainage management. They can result in unforeseen environmental contamination and deterioration in the performance of wastewater treatment plants. Consequently, pinpointing the origin of unauthorized discharges in the sewer network is crucial. This study aims to evaluate an integrative method that employs numerical modeling and statistical analysis to determine the locations and characteristics of illicit discharges. The Storm Water Management Model (SWMM) was employed to track water quality variations within the sewer network and examine the concentration profiles of exogenous pollutants under a range of scenarios. The identification technique employed Bayesian inference fused with the Markov chain Monte Carlo sampling method, enabling the estimation of probability distributions for the position of the suspected source, the discharge magnitude, and the commencement of the event. Specifically, the cases involving continuous release and multiple sources were examined. For single-point source identification, where all three parameters are unknown, concentration profiles from two monitoring sites in the path of pollutant transport and dispersion are necessary and sufficient to characterize the pollution source. For the identification of multiple sources, the proposed SWMM-Bayesian strategy with improved sampling is applied, which significantly improves the accuracy.

Optimization of LID Strategies for Urban CSO Reduction and Cost Efficiency: A Beijing Case Study

Combined sewer overflow (CSO) can lead to serious urban water environment pollution and health risks to residents. Low Impact Development (LID) facilities are one of the important measures to alleviate CSO and have been widely applied. The rational selection of LID facility types, locations, and scales is the most important task, which can effectively improve resource utilization efficiency. Based on the NSGA-II multi-objective optimization algorithm and coupled with the SWMM sewer network hydraulic model, this study takes the combined sewer overflows and the construction cost of LID facilities as optimization objectives and optimizes the types and scales of LID layout in the study area, including eight different return periods. By using the Pareto frontier and visualizing the results of the model, the effects of different rainfall return periods on the CSO control and investment cost of LID layout schemes are compared. The results show the following: (1) the optimization model can demonstrate the relationship between CSO control volume and LID construction cost under different LID layout schemes through the Pareto frontier, showing three different trends, indicating that the relationship between overflow volume and investment cost is nonlinear; (2) with the increase in rainfall intensity, higher requirements are proposed for LID schemes to meet CSO control targets, leading to a decrease in the number of Pareto frontier solution sets. Under larger rainfall intensities, it is difficult to achieve the same overflow control effect by increasing the scale of LID construction. Therefore, considering constraining the LID construction cost between RMB 5.3 and 5.38 million is helpful to determine the most suitable solution; (3) in the optimal layout schemes under different return periods, 87.3% of the locations where LID is deployed have similar scales. Based on these locations with a relatively large proportion of deployment, it can be determined that special attention should be paid to spatial positions in LID planning and construction. This study provides valuable insights for solving combined sewer overflow problems and optimizing urban drainage management and provides guidance for future planning and decision-making processes.

Model predictive control of stormwater basins coupled with real-time data assimilation enhances flood and pollution control under uncertainty

Smart stormwater systems equipped with real-time controls are transforming urban drainage management by enhancing the flood control and water treatment potential of previously static infrastructure. Real-time control of detention basins, for instance, has been shown to improve contaminant removal by increasing hydraulic retention times while also reducing downstream flood risk. However, to date, few studies have explored optimal real-time control strategies for achieving both water quality and flood control targets. This study advances a new model predictive control (MPC) algorithm for stormwater detention ponds that determines the outlet valve control schedule needed to maximize pollutant removal and minimize flooding using forecasts of the incoming pollutograph and hydrograph. Comparing MPC against three rule-based control strategies, MPC is found to be more effective at balancing between multiple competing control objectives such as preventing overflows, reducing peak discharges, and improving water quality. Moreover, when paired with an online data assimilation scheme based on Extended Kalman Filtering (EKF), MPC is found to be robust to uncertainty in both pollutograph forecasts and water quality measurements. By providing an integrated control strategy that optimizes both water quality and quantity goals while remaining robust to uncertainty in hydrologic and pollutant dynamics, this study paves the way for real-world smart stormwater systems that will achieve improved flood and nonpoint source pollution management.

Calculation of Dry Weather Flows in Pumping Stations to Identify Inflow and Infiltration in Urban Drainage Systems

The performance of most urban drainage systems is adversely affected by unintended connections of groundwater and surface water, often denoted as inflow and infiltration (I&I). Various methods exist to locate and characterise these effects. Yet, it remains difficult to quantify them accurately, especially in terms of spatial distribution over a larger drainage area. One of the reasons for this is the lack of sufficient high-quality sewer flow measurements at a high temporal resolution, which would enable the calibration of detailed spatio-temporal relationships between rainfall and I&I flows. In this paper, a methodology is presented for deriving sewer flow time series from operational measurements at pumping stations, and the results from four pilot locations are discussed. It shows the potential of the methodology to be implemented at a large scale and to contribute to a better understanding and remediation of I&I in urban drainage management planning.

Determining demand for water, water supply and drainage balance to wastewater reuse for urbans in Vietnam

Wastewater reuse is very important in ensuring a stable water supply for the socio-economic development of cities in the future. That is even more meaningful for areas affected by climate change erratic, hot, arid, scarce and polluted due to different causes. Specifically, many regions and urban areas in Vietnam have not been proactive in water resources upstream; runoff through agricultural, industrial and urban areas contaminated by farming, industrial waste, wastewater and municipal solid waste. Based on published studies on the role and situation of wastewater reuse in urbans, as well as on legal documents Vietnam's current management related to wastewater drainage and reuse, the article presents how to calculate and determine the water demand in urban areas for calculating capacity of water supply plants; to set up the balance diagram of water supply and drainage for all types of urban areas (from special to grade V urbans) and the balance diagram of water supply and drainage in the works. The research results will be considered as a scientific basis for state management agencies as well as local authorities to appropriately and effectively use in formulating strategic orientations and objectives for urban water supply and drainage management in Vietnam urban areas.

A suitable deterministic modeling approach of urban stormwater nutrient, metal and organic pollutant removal in plant biofiltration

ABSTRACT Urban water managers regard stormwater runoff and its treatment as one of the greatest challenges, due to its diffused nature and pollutant range. In response, plant biofiltration, a water-sensitive urban design technology, is increasingly preferred. However, due to varying removal performances influenced by design and operational conditions, as well as pollutant removal process complexity, it is under-utilised. This note reviews relevant pollutant removal processes and pathways; and subsequently proffers a first step summary of fundamental processes and pathways applicable to generic plant biofiltration for removal of typical stormwater pollutants. The treatment model combines relevant existing models applicable to the removal pathways of organics, NH3, NO3-, PO4 3- and metal pollutant change, as well as recommends further refinements. Advancing the understanding of plant biofilter complexity represents a significant in the urban drainage management strategy, from simple flood reduction to the recognition of the stochastic nature of interactions influencing water quality.

Incorporating Urban Drainage System Resilience in Public Policies for a City in a Developing Country—Colombia

Scientific studies have shown that conventional practices on urban drainage management are not sustainable. Resilience has emerged to manage and protect socio-ecological and socio-technical systems. This paper reviews how urban drainage system resilience has been incorporated effectively into public policies worldwide to make recommendations for a city in a developing country. To this end, we carried out literature reviews to identify key actions that other countries have implemented and determine the policy baseline at the national level for Colombia. These findings were used to formulate recommendations for incorporating resilience in national Public Policies, which were validated during a workshop with experts. At the national level, we evidenced pathways to update public policies, involving a multi-step local and national activities process. A pilot project using the Santiago de Cali Resilience Strategy was proposed to implement the initial findings and identify actions by the stakeholder group. The process can be monitored and improved to be replicated in other areas.

Climate change impacts on intensity duration frequency curves of precipitation: A case study of Shiraz synoptic station, Iran

Intensity-duration-frequency (IDF) curves are among the standard design tools for many engineering applications such as urban drainage management. Since climate change may considerably affect precipitation, updating of IDF curves is highly necessary. The present study aims to examine the impacts of climate change on IDF curves of Shiraz synoptic station using downscaled outputs of Hadcm3 AOGCM under various emission scenarios (A1B, A2,B1) applying larswg-5 model for the period of 2046 to 2065. The fitted Gumbel distribution was used to estimate the maximum short-term precipitation quantiles in the base period (1968-2000) and the verified empirical Bell type equation was used for the future period. The results show that the mean of maximum daily precipitation and annual precipitation will decrease in the future. Also, the maximum precipitation intensities up to 60 min duration will reducefrom 0.15 mm hr-1 to about 10.79 mm hr-1 compared to the observed period in all returns periods and various scenarios. Overall, there were no tangible changes in intensities for durations higher than 60 min. The highest reduction in precipitation intensity would be at the 20 min duration with 100-year return period in the A2 scenario.

Feasibility of using smart meter water consumption data and in-sewer flow observations for sewer system analysis: a case study

Abstract Globally, smart meters measuring the water consumption with a high temporal resolution at consumers' households are deployed at an increasing rate. In addition to their use for billing or leak detection purposes, smart meters may provide detailed knowledge of the wastewater inflow to the sewer systems in space and time and open up new types of system analyses aimed at closing the urban water balance. In this study, we first validate the smart meter data against other, independent water distribution data. Subsequently, we use a detailed hydrodynamic sewer system model to link the smart meter data from almost 2,000 consumers with in-sewer flow observations in order to simulate the wastewater component of the dry weather flow (DWF) and to identify potential anomalies. Results show that it is feasible to use smart meter data as input to a distributed urban drainage model, as the temporal dynamics of the model results and in-sewer flow observations match well. Furthermore, the study suggests that in-sewer flow observations may be subject to unrecognised uncertainties, which make them unsuitable for advanced investigations of the DWF composition, and this underlines the necessity of collecting data from independent sources. The study also exemplifies that digital system integration in the water sector may be complicated. However, overcoming these obstacles may improve both offline and real-time urban drainage management.

Multicriteria GIS-Based Approach in Priority Areas Analysis for Sustainable Urban Drainage Practices: A Case Study of Pato Branco, Brazil

Geographic information systems (GIS) and multicriteria decision methods are robust techniques for supporting the urban planning process, including urban drainage. New low-impact management approaches (LID) for rainwater have been investigated and have become increasingly used. Considering the central region of Pato Branco city, which suffers recurrent problems related to flooding, this work presents a method to identify potential areas for the application of LIDs, such as rainwater collection tanks, permeable pavements, green roofs, and rain gardens. The identification of these areas is based on the analysis in a GIS environment considering criteria related to both the land slope, the characteristics of land use and technical parameters. Thus, we observe that rainwater collection tanks are indicated for all habitations, permeable pavements are recommended for 6.30% of the study area, while green roofs can be implemented in 3.97% of the area. Finally, 3.03% can receive rain gardens. In total, 13.30% of the central region of Pato Branco can receive LIDs. The results obtained reveal that the use of the GIS tool associated with multicriteria analysis is efficient in choosing locations for the implementation of LIDs as alternatives for the management of urban drainage.

Climate technology transfer in BRI era: needs, priorities, and barriers from receivers’ perspective

ABSTRACT Technology is an instrument to build BRI relationships, mitigate the environmental and climate impacts of BRI projects, as well as to enhance environmental sustainability in the regions. This study aims to reposition China in global climate technology transfer in BRI era and to obtain initial knowledge on needs, priorities, and barriers from the receivers’ perspective. Focus group method with aid of questionnaire survey and follow-up face-to-face interviews was adopted to capture the major issues directly expressed by receivers from these countries. A total of 63 valid questionnaires were collected, and 13 respondents were face-to-face interviewed. The results confirmed that energy and agriculture were the most prioritized sectors for mitigation and adaptation in the developing countries alongside OBOR. The prioritized technologies for mitigation included cogeneration, solar photovoltaic, and biomass/biogas electricity. Irrigation, conservation agriculture, and soil management were prioritized for adaptation in agricultural sector, and water recycling and reuse, source water protection, and urban drainage management in water resource sector. Technology cost during installation and operation was stressed as the most important factor constraining the application and diffusion of climate technologies. But communication including language, information, and ways of communication, was also identified as an important factor. This implied that the conventional climate technology transfer need adapt to changing contexts of BRI and be complemented with innovative approaches involving multi-actors in different phases of climate technology development. Due to the limited representativeness of the sample, the results can hardly be generalized to all the countries, but raised interesting topics for future researches.

Integrated Urban Drainage Management for Flood Inundation Controlling in Sidokare Area at Sidoarjo Regency

Flood and inundation had become a serious problem in Sidoarjo Regency annually. This study aimed to apply integrated urban drainage management for flood inundation controlling at Sidokare Region in Sidoarjo Regency. This integrated drainage management consisted of retarding pond, drainage channel redesign, and pump utilization. The study region was divided into Sidokare Pump station, Sepande, and Diponegoro Street catchment area. Rainfall intensity during historical floods was analysed using Mononobe formula and Log Pearson Type III method was used to analyze design rainfall. From the result of the analysis, it wasfoundthat thehistoricalfloodsinstudyregioncausedbyrainfall withreturnperiodof1.01 years, with rainfall intensity of 17.55 mm/hour. It was also found that by implementing this integratedurbandrainagemanagementatSidokareRegion,floodcouldbereducedupto100%. ForSidokarePumpStationcatchmentarea,theinundationmanagementwasconductedbyusing combination of storage pool, existing drainage channel, and the existing flood pump. For Sepandecatchmentarea,itwasmanagedtousethecombinationofstoragepoolandtheexisting drainage channel. Meanwhile, Diponegoro Street catchment area was solved by utilizing new flood pump combining with new tertiary channel and existing drainagechannel.

Socio-technological tool for mapping susceptibility to urban flooding

The intensification of flooding in urban areas and the management of susceptibility areas has become a global issue and has been the subject of several studies in recent decades. The integration of alternative approaches, such as socio-hydrological and socio-technological sciences, has gained prominence in urban space planning and development. The mapping of environmental susceptibility represents a promising alternative for the integrated management of natural disasters. However, for this to be used as a socio-technological tool, transiting to a participative management of urban environment, it is necessary to simplify and reduce the associated costs. In this sense, the objective of this study was to propose a socio-technological tool for the punctual and spatial mapping of the susceptibility to the occurrence of flooding in urban regions. The method is designed to combine ease and low cost of application with a simplified but physically sensitive socio-hydrological assessment of eight factors of influence. The methodological tool was tested in a Brazilian district where entire socio-hydrological scenario of urban flooding in developing countries is observed. The results show that the method can provide a simple and consistent view, reaching an overall accuracy of 73.67% of the flooding points. In general, the method provides information that can support decision-making by government agencies in developed and developing countries, as well as civil society, in relation to participatory urban zoning, drainage management, and water conservation.

Numerical modeling for the urban drainage gallery systems design

ABSTRACT Considering the frequent flooding of urban centers, the financial limitations and the inefficient management of Urban Drainage (UD) systems in Brazilian municipalities, it is necessary that projects be developed efficiently. These objectives are achieved with the correct definition of the diameter and galleries slope, resulting in adequate hydraulic ratios. It is also necessary to guarantee the flow without backwater, by verifying the energy grade line along the network. There are software capable of assisting the calculation, which, however, do not report optimized solutions. A vector-based numerical modeling is presented for the optimized sizing of a UD gallery system. This model was applied in an area and its results were compared with those obtained by two software in the Brazilian market. It is demonstrated the optimization developed contributes to increases the efficiency in the design. The main scientific contributions are: to characterize and model the typical design slopes, to obtain the optimum slope combined with the smaller diameter; to explore the potential of the hydraulic ratios above those normally employed, with positive effects on the definition of {D, ig} and the economy in the system; and to implement a recursive solution from a cycle of interdependent information, ensuring accuracy of results.

Methodology for the construction of an urban flood hazard chart

ABSTRACT Flood events are one of the major causes of economic loss and the loss of life worldwide. Unfortunately, their occurrence has become increasingly more frequent and of greater magnitude. In order to minimize the population’s exposure to danger, it is necessary to invest in tools that aid in the decision-making process related to urban drainage management. The present work proposes a methodology for the construction of a Flood Hazard Chart for urban watersheds. The Storm Water Management Model (SWMM) was applied to the Cachoeirinha Watershed (Belo Horizonte, Brazil). The model was calibrated and validated using precipitation data and water levels recorded in monitoring stations located in the study area. The Nash-Sutcliffe Coefficients for the calibration and validation were 0.72 and 0.70, respectively. The performance of the model was satisfactory, although the model was not able to represent the more intense rain events that led to emergency and overflow warnings. Modeling results allowed the construction of the hazard chart, which defined hazard ranges or warning levels of hazard as a function of accumulated rainfall and duration. The constructed graph was assessed from real precipitation events and proved to be valid, since most events corresponded with the defined warning levels in the chart. The Flood Hazard Chart proposed in this research is a valuable tool for flood risk management as it has the potential to reduce exposure to flood disasters.

Modified NRCS-CN-TUH methods for distributed rainfall-runoff modeling

ABSTRACT Due to the relative ease of application, the CN and the Triangular Unit Hydrograph (TUH) methods are commonly used in hydraulic facilities design. This work adapts these methods to incorporate the spatial variability of the physical characteristics of the catchment. The flow travel time (tv) is computed from the DEM and the CN and TUH methods are adapted to produce results on a pixel basis. This methodology is applied to the Cascata I catchment (Porto Alegre - RS), considering two variants: i) TUHout - tv calculated from each pixel up to the catchment outlet; ii) TUHdown - tv computed from one pixel to the immediate downstream. The proposed methodology showed potential to be used for hydrologic modeling of rainfall events in small catchments, as an alternative for providing information useful for urban drainage management, as the characterization of catchment areas with distinct behavior regarding velocities and potential for runoff generation. On the other side, the results showed an underestimation of peak discharges and time to peak. Initial abstraction losses of the CN method lower than the one originally prescribed provided more realistic results, in agreement to recent studies. There is the need for an improvement of the methodology for the characteristics of the Brazilian catchments besides the simple adaptation of the classical equations of the CN method to its distributed form.

O planejamento da drenagem urbana em cidades médias do Triângulo Mineiro e Alto Paranaíba

As relações entre o meio ambiente e as cidades se modificaram ao longo dos anos em função, sobretudo, do desenvolvimento econômico e das funcionalidades assumidas pelo espaço urbano. Tais modificações trouxeram diversos problemas ambientais que desafiam os planejadores, não apenas nas grandes metrópoles. As cidades médias, por apresentarem uma ocupação menos densa em relação às grandes cidades, e por terem uma legislação ainda em desenvolvimento no que diz respeito à drenagem urbana, apresentam maiores possibilidades para adequar seu planejamento para essa temática. Neste trabalho são discutidas medidas aplicadas no planejamento de drenagem urbana propostas para seis cidades médias do Triângulo Mineiro e Alto Paranaíba. Entre os resultados encontrados, destacaram-se a desarticulação da participação popular no processo de planejamento, diferenças de custo entre diversas medidas e as justificativas para a implantação de algumas medidas adotadas, quase sempre amparadas por problemas que poderiam ser evitados com uma gestão prévia da ocupação urbana.