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.
| Original language | English |
|---|---|
| Pages (from-to) | 805-818 |
| Number of pages | 14 |
| Journal | Journal of Hydrology |
| Volume | 571 |
| DOIs | |
| Publication status | Published - Apr 2019 |
Bibliographical note
Funding Information:The work described in this paper was part of an interdisciplinary project programme undertaken by the Blue-Green Cities ( www.bluegreencities.ac.uk ) and Urban Flood Resilience in an Uncertain Future ( www.urbanfloodresilience.ac.uk ) research consortia. The consortia is funded by the UK Engineering and Physical Sciences Research Council under grants of EP/K013661/1 and EP/P004318/1 , with additional contribution from the Environment Agency and Rivers Agency (Northern Ireland). The authors thank the Environment Agency and Newcastle City Council for providing rainfall, DTM, land-use data sets and design drawings of the Newcastle Great Park development which were incorporated in this study. The authors also thank three anonymous reviewers for their critical and constructive comments to improve the quality of the paper. Appendix A
Publisher Copyright:
© 2019
Keywords
- Flood resilience
- Hydro-morphodynamic modelling
- Long-term performance
- Sediment dynamics
- Stormwater pond
- Urbanisation
ASJC Scopus subject areas
- Water Science and Technology