An Integrated Hydrological-CFD Model for Estimating Bacterial Levels in Stormwater Ponds

Farzam Allafchi,Caterina Valeo,Norman F Neumann,Jianxun He

doi:10.3390/w11051016

Farzam Allafchi, Caterina Valeo + Show 2 more

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https://doi.org/10.3390/w11051016

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Abstract

A hydrological model was integrated with a computational fluid dynamics (CFD) model to determine bacteria levels distributed throughout the Inverness stormwater pond in Calgary, Alberta. The Soil Conservation Service (SCS) curve number model was used as the basis of the hydrological model to generate flow rates from the watershed draining into the pond. These flow rates were then used as input for the CFD model simulations that solved the Reynolds-Averaged Navier-Stokes (RANS) equations with k-ɛ turbulence model. E. coli, the most commonly used fecal indicator bacteria for water quality research, was represented in the model by passive scalars with different decay rates for free bacteria and attached bacteria. Results show good agreement with measured data in each stage of the simulations. The middle of the west wing of the pond was found to be the best spot for extracting water for reuse because it had the lowest level of bacteria both during and after storm events. In addition, only one of the four sediment forebays was found efficient in trapping bacteria.

Highlights

In recent decades stormwater has been considered as an alternative water source for reuse, for applications that need less than pristine water quality
The curve number (CN) number for the subbasin draining to I5 was calculated to be 11% less than the initially
The CN number for the subbasin draining to I5 was calculated to be 11% less than the initially calculated CN value in the calibration of the 6 June 2007 event

Summary

Introduction

In recent decades stormwater has been considered as an alternative water source for reuse, for applications that need less than pristine water quality. Reusing stormwater is more critical in water-scarce regions and regions where rainfall patterns and rainfall frequencies are changing [1]. Stormwater ponds are built with the primary objective of reducing runoff quantities in order to protect urban areas against flooding, they improve the quality of stormwater as well [1]. Stormwater recycling with pond water often requires continuous or intermittent water quality monitoring of the pond water in order to remain compliant with local regulations. Distributed water quality sampling in stormwater ponds is often impractical due to the sizes of these ponds and the cost

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