Impact of Short Duration Intense Rainfall Events on Sanitary Sewer Network Performance

Nasrin, Tasnim; Sharma, Ashok; Muttil, Nitin

doi:10.3390/w9030225

Cited by 30 publications

(13 citation statements)

References 41 publications

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“…Various modelling studies have applied continuous rainfall data to simulate CSO discharges under baseline and climate change scenarios (Abdellatif et al 2014, Abdellatif et al 2015, Dirckx et al 2017, Nie et al 2009, Nilsen et al 2011, Semadeni-Davies et al 2008; to analyse stormwater control performance for CSO reductions (Dirckx et al 2011, Lucas and Sample 2015, Montalto et al 2007, Tavakol-Davani 2016; to validate CSO solution designs (Shoemaker et al 2011); to address the impact of rainfall spatial variability on CSO volumes (Verwom and Stuecken 2001); to evaluate combined sewer system performance under dry and wet years (Nasrin et al 2017); or to assess modelling performances for CSO impact estimations (Ruan 1999, Vaes et al 2001. It could be noted that whereas most studies analysed CSO by comparing resulting volume, duration and/or frequency, the study of Ruan (1999) also assessed water quality impacts of CSOs on receiving waters by evaluating model simulation accuracies for estimating total suspended solids loads and concentrations.…”

Section: Continuous and Quasi-continuous Rainfall Datamentioning

confidence: 99%

Selection of rainfall information as input data for the design of combined sewer overflow solutions

Jean

Duchesne

Pelletier

et al. 2018

Journal of Hydrology

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Combined sewer overflows (CSOs) cause environmental problems and health risks, but poor guidance exists on the use of rainfall data for sizing optimal CSO control solutions. This study first reviews available types of rainfall information as input for CSO modelling and, secondly, assesses the impacts of three rainfall data selection methods (continuous simulation, historical rainstorms selected based on rainfall depth or maximum intensity and IDF-derived storms) on the estimation of CSO volume thresholds to control in order to reach specific seasonal CSO frequency targets. The methodology involves hydrological/hydraulic modelling of an urban catchment in the Province of Québec (Canada). Continuous simulation provides the most accurate volume estimations and shows high sensitivity to the number of simulated *Revised Manuscript with no changes marked Click here to view linked References 2 years. Alternatively, when historical events extracted from rainfall data separated by a minimum inter-event time (MIT) criterion are selected based on their total rainstorm depth, the CSO volumes are underestimated significantly; whereas an analysis based on rainstorm maximum intensities over durations similar to the time of concentration provides more conservative volumes. Finally, synthetic storms constructed from multiple points of an IDF curve tend to underestimate slightly the CSO volumes, but provide acceptable results compared to single point derived storms. It was found that the overflow structures local characteristics had a marginal influence on results obtained from continuous simulation compared to event-based simulation. The use of design rainfall events should thus be restricted to preliminary assessment of CSO volume thresholds, and the final volume estimation for solution sizing should be reviewed under continuous simulation. The innovative contribution lies in the improvement of modelling procedures for solutions design to achieve a maximum CSO frequency, such as specified by many regulating agencies.

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Section: Continuous and Quasi-continuous Rainfall Datamentioning

confidence: 99%

Selection of rainfall information as input data for the design of combined sewer overflow solutions

Jean

Duchesne

Pelletier

et al. 2018

Journal of Hydrology

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“…The uncertainty of runoff from the SWMM model was evaluated through parameter calibration [6][7][8]. Runoff caused by extreme rainfall and the overflowing manholes were simulated [9]. To simulate stormwater pipe network, the network must be simplified [10].…”

Section: Introductionmentioning

confidence: 99%

Evaluation of the Structure of Urban Stormwater Pipe Network Using Drainage Density

Lee

Chung

Park

et al. 2018

Water

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In mega cities such as Seoul in South Korea, it is very important to protect the cities from surface flooding even for a short time period due to the enormous economic damage. That is why stormwater pipe networks are commonly applied to mega cities with large impervious areas to drain runoff from the city. Therefore, the stormwater pipe networks in urban catchments should be carefully designed for quick and efficient runoff removal. In this study, the structures of different stormwater pipe networks were evaluated based on the relationship between peak rainfall and runoff in the urban catchments in South Korea. More than 400 historical rainfall events from five urban catchments were used to develop respective linear regression models for estimating peak runoff for different pipe network structures. The developed regression models exhibited greater than 0.9 in determination coefficients and demonstrated overall the broader ranges in peak runoff with the greater rainfall amount, especially when the pipe networks were branched. This implies that the effect of pipe network structures on runoff is more profound in the branched networks whose runoff water flow is one-directional and thus tends to concentrate to the catchment outlet. In the case of the looped networks in which runoff paths are multiple, rainfall runoff can be routed to several alternative water paths depending on rainfall events resulting in the reduced peak runoff. The structures of pipe networks can be measured in drainage density which is defined as the ratio of total pipe length to catchment area. As a result, the range of the estimated runoff at the 95% confidence level increased as the drainage density increased, which implies increased uncertainty with the looped networks which commonly involve more pipe installation for unit area as compared to the branched. However, the looped networks with multiple water paths can reduce the time to drain rainfall from the catchments and thus the 95% confidence interval becomes narrow, which means greater reliability in peak runoff estimation. It would therefore be favorable to adopt looped stormwater pipe networks within an affordable budget and the complexity of pipe networks needs to be counted to reduce urban flood risk.

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“…In urban catchments, important rainfall events last a few hours or even minutes, and therefore the time step of measurement records is usually only of a few minutes. The urban drainage literature reports NSE values from the calibration of hydrologic or hydraulic models, normally between 0.5 and 0.9 [2], most of them being greater than 0.7 [7,10,20,22,[46][47][48][50][51][52][53]. However, in some cases, NSE values above 0.95 are reported [1,53,55], while in other specific cases, usually for water quality parameters, very low values, close to zero, are considered as acceptable [9].…”

Section: Main Metrics Used In Calibration and Assessment Of Hydrologi...mentioning

confidence: 99%

“…For example, in a model developed for flood risk assessment, emphasis is put on calibrating peak flows of the most severe storms [11,12], while in a model designed to manage combined sewer overflows (CSO), greater accuracy is required in calibrating the volumes of hydrographs for a much wider range of events, which includes medium and small magnitude rainfall [13][14][15]. In the latter case in particular, daily and seasonal variations in dry weather flow [16] and rainfall derived infiltration and inflow (RDII) may play a very important role [17][18][19][20][21].…”

Section: Introductionmentioning

confidence: 99%

Quality Assessment of Small Urban Catchments Stormwater Models: A New Approach Using Old Metrics

David

Mota

2022

Hydrology

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Small urban catchments pose challenges in applying performance metrics when comparing measured and simulated hydrographs. Indeed, results are hampered by the short peak flows, due to rainfall variability and measurement synchronization errors, and it can be both difficult and inconvenient to remove base flows from the analysis, given their influence on combined sewer overflow (CSO) performance. A new approach, based on the application of metrics to peak flows for a selected set of different durations, is proposed and tested to support model quality assessment and calibration. Its advantages are: avoiding inconveniences arising from lags in peak flows and subjectivity of possible adjustments; favouring the assessment of the influence of base flow variability and flow lamination by CSOs; promoting integrated analysis for a wide range of rainfall events; facilitating bias identification and also guiding calibration. However, this new approach tends to provide results (e.g., for NSE, r2 and PBIAS) closer to optimal values than when applying metrics to compare the measured and simulated values of hydrographs, so the comparison of results with thresholds widely used in the literature should be done with caution. The various case study examples highlight the importance of using a judicious set of different metrics and graphical analyses.

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Impact of Short Duration Intense Rainfall Events on Sanitary Sewer Network Performance

Cited by 30 publications

References 41 publications

Selection of rainfall information as input data for the design of combined sewer overflow solutions

Selection of rainfall information as input data for the design of combined sewer overflow solutions

Evaluation of the Structure of Urban Stormwater Pipe Network Using Drainage Density

Quality Assessment of Small Urban Catchments Stormwater Models: A New Approach Using Old Metrics

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