Wetland Feasibility Study Hydraulic Modelling, Ireland
- Alastair Sheppard
- Dec 3, 2024
- 3 min read
Updated: 11 hours ago
What our customers say:
“Flood Modeller allowed us to simulate a variety of hydrological regimes throughout Ireland, and consistently produces accurate and reliable quantitative results.”
Micheal O'Flatharta, Project Hydrologist, IE Consulting
Corke Valley Park, situated in the townland of Cork Great, County Dublin, Ireland, is a public park through which the Wilford Stream flows, eventually discharging into the Irish Sea to the east. IE Consulting were commissioned by Denyer Ecology, on behalf of Dún Laoghaire-Rathdown County Council, to conduct a hydrological characterisation of the Wilford Stream and its catchment area within Corke Valley Park.
This assessment supported a feasibility study aimed at creating an educational wetland in Corke Valley Park. The plan was to construct the wetland offline from the Wilford Stream, allowing a portion of the stream's flow to pass through the proposed wetland without disrupting the stream's maintenance flows.
To ensure the proposed wetland did not increase flood risk in other areas of Corke Valley Park or cause higher velocities within the Wilford Stream, a detailed hydraulic model was developed using Flood Modeller.
The wetland construction plan included building an embankment along the right-hand bank of the Wilford Stream, excavating the wetland's footprint, and constructing a viewing platform adjacent to the wetland for educational purposes.
To understand the current hydrological regime within the Wilford Stream, a hydraulic model was built using Flood Modeller. Initially, an integrated 1D-2D linked model was developed. However, due to the flat floodplain of the Wilford Stream, where water easily flows overbank even during small rainfall events, and the braiding of the channel within Corke Valley Park, the 1D component did not accurately represent the natural flow. Consequently, the model was redesigned as an entirely 2D model in Flood Modeller.
The Wilford Stream model was developed using high-quality topographic survey data procured specifically for this assessment. All drains, river channels, and hydraulic structures within Corke Valley Park were explicitly modelled, with Z-lines used to represent the invert levels of the Wilford Stream channel.
This approach in Flood Modeller allowed for the flow-constricting nature of the culverts to be accounted for while maintaining the complex 2D flow paths within the Wilford Stream floodplain.
The baseline scenario, representing the current hydrological regime within Corke Valley Park, was first run in the model. The results showed that the 2D peak velocities within the Wilford Stream catchment were highest within the channel and reduced in the floodplain.
For this assessment, the 2D flood extent, depth, and velocity outputs from Flood Modeller were invaluable. They enabled minor adjustments to the proposed wetland's position to minimise its impact on surrounding velocities and flood extents.
Key Facts
Feasibility study to create an educational wetland in Corke Valley Park, Co. Dublin.
IE Consulting was commissioned to prepare a hydrological characterisation of the Wilford Stream and its catchment.
Developed a 2D hydraulic model to assess the impact of the proposed wetland, embankment, and viewing area.
Utilised 2D outputs to design a wetland that minimally impacted the existing hydrological regime while ensuring a suitable design.
Modelled five culverts along the Wilford Stream using the embedded structures tool in Flood Modeller.
Once the baseline scenario was completed, the model was updated to include the proposed ground levels for the wetland area, the embankment along the right-hand side of the Wilford Stream, and the floor-level viewing area to the right of the wetland. The model was then re-run to assess the impact of these features on the surrounding hydrological regime.
The 2D velocity results in the proposed scenario indicated no significant increase in velocities within the Wilford Stream, nor did they result in unsuitably high velocities within the proposed wetland itself. The baseline flood extents were compared against the proposed flood extents, and no increase was noted in the vicinity of the proposed wetland or any other areas within Corke Valley Park.
Flood Modeller enabled the modelling of complex flow paths in the Wilford Stream while accurately representing the constriction from hydraulic structures. The detailed 2D results output by Flood Modeller greatly enhanced our understanding of the hydrological regime of Corke Valley Park. This allowed us to design a wetland that minimally impacted the existing hydrological regime while still delivering a suitable design.
