Cincinnati’s SWMM Model: A Journey Through Time

Shamsi, Uzair M.; Gamble, Ben; Koran, Joseph

doi:10.14796/jwmm.c398

Cited by 3 publications

(4 citation statements)

References 3 publications

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“…The Q-filter was used in the present work, but it was discovered that a similar damping filter was also needed for the surcharged pressure head in pipes. An equivalent H-filter can be derived by simply replacing Q with H in the flowrate oscillation damping filter presented in Hodges and Liu [31]-see their Equations (18)- (22). Herein, the H-filter only applies to surcharged cells and does not alter mass conservation.…”

Section: Timescale Interpolation From Finite-volume Elements To Facesmentioning

confidence: 99%

“…There is an ongoing need for city-wide models of stormwater networks to facilitate real-time modeling and operational control [1][2][3], design for urban growth [4][5][6], low-impact development [7][8][9], flood mitigation [10][11][12], runoff water quality [13], and address impacts of the changing climate [14,15]. Such models must be computationally efficient to allow a large number of simulations for calibration [16], design optimization [17,18], Monte-Carlo uncertainty analysis [19], and simulation of stochastic rainstorms instead of a single design storm [20,21]; however, the models must also be detailed and comprehensive is their treatment of the piping system for an entire city [22]. Two major…”

Section: Introductionmentioning

confidence: 99%

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An Artificial Compressibility Method for 1D Simulation of Open-Channel and Pressurized-Pipe Flow

Hodges

2020

Water

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Piping systems (e.g., storm sewers) that transition between free-surface flow and surcharged flow are challenging to model in one-dimensional (1D) networks as the continuity equation changes from hyperbolic to elliptic as the water surface reaches the pipe ceiling. Previous network models are known to have poor mass conservation or unpredictable convergence behavior at such transitions. To address this problem, a new algorithm is developed for simulating unsteady 1D flow in closed conduits with both free-surface and surcharged flow. The shallow-water (hydrostatic) approximation is used as the governing equations. The artificial compressibility (AC) method is implemented as a dual-time-stepping discretization for a finite-volume solver with timescale interpolation used for face reconstruction. A new formulation for the AC celerity parameter is proposed such that the AC celerity matches the equivalent gravity wave speed for the local hydraulic head—which has some similarities to the classic Preissmann Slot used to approximate pressurized flow in conduits. The new approach allows the AC celerity to be set locally by the flow (i.e., non-uniform in space) and removes it as a free parameter of the AC solution method. The derivation of the AC method provides for only a minor change in the form of the solution equations when a computational element switches from free-surface to surcharged. The new solver is tested for both unsteady free-surface (supercritical, subcritical) and surcharged flow transitions in a circular pipe and is implemented in an open-source Python code available under the name “PipeAC.” The results are compared to laboratory experiments that include rapid flow changes due to opening/closing of gates. Results show that the new algorithm is satisfactory for 1D representation of unsteady transition behavior with two caveats: (i) sufficient grid resolution must be applied, and (ii) the shallow-water equation approximations (hydrostatic, single-fluid) limit the accuracy of the solution with regards to the celerity of the turbulent unsteady bore that propagates upstream. This research might benefit any piping network model that must smoothly handle unsteady transitions from free surface to surcharged flow.

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Section: Timescale Interpolation From Finite-volume Elements To Facesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

An Artificial Compressibility Method for 1D Simulation of Open-Channel and Pressurized-Pipe Flow

Hodges

2020

Water

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“…The final WWIP was approved by the U.S. Environmental Protection Agency (USEPA) and the Department of Justice in 2009 and it calls for system wide improvements to address CSOs and SSOs. These improvements are to be implemented over the next 20 y with a total estimated construction value of $1.145 billion for Phase 1 (by December 2018) and an additional $2.0 billion for Phase 2 projects (Shamsi et al 2016). …”

Section: Green Infrastructure Cincinnati Ohiomentioning

confidence: 99%

Green First Approach for Wet Weather Programs

Shamsi

2018

JWMM

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Many United States and Canadian cities have recently started to initiate combined sewer overflow (CSO) and sanitary sewer overflow (SSO) control projects to comply with their regulatory mandates (permits and consent decrees). The capital costs of these projects are estimated to be in hundreds of millions of dollars. Both conventional gray and new green infrastructure solutions are generally required but some communities are more interested in a green first approach that requires realizing the full potential of green solutions before committing to gray solutions. This paper suggests that green infrastructure is not a panacea and green first does not mean green only. Comparing the life cycle costs and hydraulic performance of green and gray solutions is essential in the justification of a green first approach. A good green first approach should maximize the strengths and minimize the limitations of both the gray and green solutions. This paper compares green and gray infrastructure and discusses green vs gray cost and performance comparison approaches and tools. Real world examples are included and relevant software tools and models are summarized.

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“…The reasons for continuing with the project given the current model status may include the relative size of the areas that don't qualify as fully calibrated and verified, or the degree to which the model (or parts thereof ) are out of C&V criteria. Table 2 shows Shamsi's model application criteria which can be used to make the best use of the partially calibrated and/ or verified models (Shamsi 2016;Shamsi et al 2016). In 2014, the WaPUG website acknowledged that their modeling code of practice was some twelve years old and in need of a major update to reflect the current needs of the industry.…”

Section: Wapug Criteriamentioning

confidence: 99%

Continuous Calibration

Shamsi

Koran

2017

JWMM

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Generally, event based rainfall-runoff model calibration and verification is a laborious and expensive activity. With the availability of long term continuous flow meter and rainfall data and faster computers and software, models can now be calibrated to a long term flow record spanning from few months to several years. The practice of model calibration for large and complex regional systems is evolving over the years away from the conventional event based two step calibration and verification process to a more efficient single step continuous calibration process. This paper describes and compares the event and continuous calibration methods. It also presents information and comparison of various statistical methods to objectively quantify the goodness-of-fit statistics for model calibration that can be used in continuous calibration. Examples are provided from the Metropolitan Sewer District of Greater Cincinnati (MSDGC) SWMM model which is one of the largest SWMM model in the world.

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Cincinnati’s SWMM Model: A Journey Through Time

Cited by 3 publications

References 3 publications

An Artificial Compressibility Method for 1D Simulation of Open-Channel and Pressurized-Pipe Flow

An Artificial Compressibility Method for 1D Simulation of Open-Channel and Pressurized-Pipe Flow

Green First Approach for Wet Weather Programs

Continuous Calibration

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