Modelling the long-term suspended sedimentological effects on stormwater pond performance in an urban catchment

Sangaralingam Ahilan, Mingfu Guan, Nigel Wright, Andrew Sleigh, Deonie Allen, Scott Arthur, Heather Haynes, Vladimir Krivtsov

Research output: Contribution to journalArticle

Abstract

The influence of long-term suspended sediment dynamics on stormwater pond performance should not be ignored, but is often neglected in pond design and performance evaluation. This paper provides systematic simulated quantification of long-term suspended sedimentological effects on stormwater pond performance. Integrated hydrological and two-dimensional hydro-morphodynamic modelling and simulations were carried over a 32-year period (1984–2015) covering 3896 rainfall events with a wide range of rainfall volumes, durations and intensities. Three event-based hypothetical rainfall scenarios: non-flood condition (5-year), sewer design condition (30-year), and river flood condition (100-year) rainfall events with 1-h duration, were also simulated for comparison between the traditional event-based approach and the novel approach presented in this study. Simulation results show that the flood peak attenuation and delay are more pronounced for small (<5-year) and medium (<30-year) flood events. The long-term continuous simulation results indicate that the pond provides positive annual trap efficiencies varying from 2% to 69% for 31 of 32 years, providing long-term water quality benefits downstream. However, an extreme rainfall event in year 2012 flush out the accumulated sedimentation as a shock load to the downstream river, leading to a negative trap efficiency of −11%. The spatially averaged sediment deposition rate, as predicted by the model, varies with a mean (SD) of 2 (1.34) cm/year over the study period, which resulted in a 24% loss in the pond's volume over 32 years. The impact of the loss in storage on pond flood attenuation capacity are explored at regular time intervals over the study period. The results indicate that reduction in the pond's flood attenuation capacity is relatively more pronounced for medium (30-year) and extreme (100-year) flood events than the frequent small flood (5-year) events. The variation in annual sediment loading with rainfall quantities and patterns are also explored.

LanguageEnglish
Pages805-818
Number of pages14
JournalJournal of Hydrology
Volume571
Early online date13 Feb 2019
DOIs
Publication statusPublished - Apr 2019

Fingerprint

stormwater
pond
catchment
rainfall
modeling
simulation
morphodynamics
effect
river
suspended sediment
sediment
sedimentation
water quality

Keywords

  • Flood resilience
  • Hydro-morphodynamic modelling
  • Long-term performance
  • Sediment dynamics
  • Stormwater pond
  • Urbanisation

ASJC Scopus subject areas

  • Water Science and Technology

Cite this

Ahilan, Sangaralingam ; Guan, Mingfu ; Wright, Nigel ; Sleigh, Andrew ; Allen, Deonie ; Arthur, Scott ; Haynes, Heather ; Krivtsov, Vladimir. / Modelling the long-term suspended sedimentological effects on stormwater pond performance in an urban catchment. In: Journal of Hydrology. 2019 ; Vol. 571. pp. 805-818.
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abstract = "The influence of long-term suspended sediment dynamics on stormwater pond performance should not be ignored, but is often neglected in pond design and performance evaluation. This paper provides systematic simulated quantification of long-term suspended sedimentological effects on stormwater pond performance. Integrated hydrological and two-dimensional hydro-morphodynamic modelling and simulations were carried over a 32-year period (1984–2015) covering 3896 rainfall events with a wide range of rainfall volumes, durations and intensities. Three event-based hypothetical rainfall scenarios: non-flood condition (5-year), sewer design condition (30-year), and river flood condition (100-year) rainfall events with 1-h duration, were also simulated for comparison between the traditional event-based approach and the novel approach presented in this study. Simulation results show that the flood peak attenuation and delay are more pronounced for small (<5-year) and medium (<30-year) flood events. The long-term continuous simulation results indicate that the pond provides positive annual trap efficiencies varying from 2{\%} to 69{\%} for 31 of 32 years, providing long-term water quality benefits downstream. However, an extreme rainfall event in year 2012 flush out the accumulated sedimentation as a shock load to the downstream river, leading to a negative trap efficiency of −11{\%}. The spatially averaged sediment deposition rate, as predicted by the model, varies with a mean (SD) of 2 (1.34) cm/year over the study period, which resulted in a 24{\%} loss in the pond's volume over 32 years. The impact of the loss in storage on pond flood attenuation capacity are explored at regular time intervals over the study period. The results indicate that reduction in the pond's flood attenuation capacity is relatively more pronounced for medium (30-year) and extreme (100-year) flood events than the frequent small flood (5-year) events. The variation in annual sediment loading with rainfall quantities and patterns are also explored.",
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Modelling the long-term suspended sedimentological effects on stormwater pond performance in an urban catchment. / Ahilan, Sangaralingam; Guan, Mingfu; Wright, Nigel; Sleigh, Andrew; Allen, Deonie; Arthur, Scott; Haynes, Heather; Krivtsov, Vladimir.

In: Journal of Hydrology, Vol. 571, 04.2019, p. 805-818.

Research output: Contribution to journalArticle

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