Modelling stormwater runoff, quality, and pollutant loads in a large urban catchment

Maharjan, Bharat; Pachel, Karin; Loigu, Enn

doi:10.3176/proc.2017.3.02

Cited by 16 publications

(13 citation statements)

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“…where K W is a washoff coefficient, q is the runoff rate over the subcatchment, and N W is a washoff exponent (U. S. Envrionmental Protection Agency 2016). Generic values for these empirically derived coefficients and exponential terms for modeling pollutant loads are available in the EPA SWMM Reference Manuals (U. S. Envrionmental Protection Agency 2016), although these parameters can be highly variable and controlled by localized factors, including landscape topography and land use (Di Modugno et al 2015;Maharjan, Pachel, and Loigu 2017;Muthusamy et al 2018).…”

Section: Modeling Cesium Washoffmentioning

confidence: 99%

“…The washoff parameter values we used in this case study were informed by published values from studies of TSS washoff featuring similar land use types (Temprano et al 2006;Hood, Reihan, and Loigu 2007;Maharjan, Pachel, and Loigu 2017). The range of values reported in these studies, along with site-specific knowledge of our study area and a simple assessment with a cumulative loss model, guided washoff coefficient and exponent selection for this case study (Table 2).…”

Section: Modeling Cesium Washoffmentioning

confidence: 99%

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Modeling radionuclide transport in urban overland flow: a case study

Shireman¹,

Ratliff

Mikelonis

2021

Urban Water Journal

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This paper presents a case study demonstrating the process used to develop an overland flow model of radionuclide transport following an aerosol deposition from a hypothetical radiological dispersal device explosion. The process included the integration of digital elevation, building, and land cover information with hydrologic information from a calibrated Stormwater Management Model (SWMM) model. The overland flow model was used to explore the impact of washoff parameter selection and different storm events on radionuclide transport in surface flow. The range of washoff parameters used in the literature resulted in over a 7 times difference in radionuclide washoff, from a small surface removal to nearly full removal. The overland flow model illuminated the primary pathways of contaminant transport, a potentially useful tool that informs emergency response, planning, and remediation activities.

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Section: Modeling Cesium Washoffmentioning

confidence: 99%

Section: Modeling Cesium Washoffmentioning

confidence: 99%

Modeling radionuclide transport in urban overland flow: a case study

Shireman¹,

Ratliff

Mikelonis

2021

Urban Water Journal

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“…Equations (13), (15) and (16) constitute the dual-time marching system of PipeAC that is applicable in a system with mixed open-channel and surcharged conduits. From any discrete time step n in real time we take pseudo-time steps m = {1, 2, 3...} until we reach a pseudo-time steady-state (∂/∂τ = 0), at which point we will have converged to the discrete real-time march equations for the unknown n + 1 step: momentum:…”

Section: Semi-discrete Governing Equationsmentioning

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].…”

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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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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“…The estimation of stormwater quantity has been a requirement in evaluating compliance of stormwater management regulations and in implementing effective control measures [ 13 ]. Many studies have used field measurements, experimental watersheds, and statistical modeling to evaluate the impact of urbanization on surface direct runoff [ 1 , 14 , 15 , 16 ].…”

Section: Introductionmentioning

confidence: 99%

Assessing the Impact of Urbanization on Direct Runoff Using Improved Composite CN Method in a Large Urban Area

Liu

et al. 2018

IJERPH

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Urbanization is one of the most widespread anthropogenic activities, which brings a range of physical and biochemical changes to hydrological system and processes. Increasing direct runoff caused by land use change has become a major challenge for urban ecological security. Reliable prediction of the quantity and rate of surface runoff is an inherently difficult and time-consuming task for large ungauged urban areas. In this study, we combined Geographic Information System and remote sensing technology with an improved Soil Conservation Service curve number model to evaluate the effects of land use change on direct runoff volume of the four-ring area in Shenyang, China, and analyzed trends of direct runoff at different scales. Through analyzing trends of direct runoff from 1984 to 2015 at different scales, we explored how urbanization and other potential factors affect direct runoff changes. Total direct runoff volume increased over time, and trends varied from the inner urban area to suburban area. Zones 1 and 2 had a tendency toward decreasing direct runoff volume and risks, while Zones 3 and 4 showed gradual increases at both regional and pixel scales. The most important influence on direct runoff change was urban surface change caused by urbanization. This study presents a framework for identifying hotspots of runoff increase, which can provide important guidance to urban managers in future green infrastructure planning, in the hopes of improving the security of urban water ecological patterns.

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Modelling stormwater runoff, quality, and pollutant loads in a large urban catchment

Cited by 16 publications

References 0 publications

Modeling radionuclide transport in urban overland flow: a case study

Modeling radionuclide transport in urban overland flow: a case study

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

Assessing the Impact of Urbanization on Direct Runoff Using Improved Composite CN Method in a Large Urban Area

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