Ballygow Farm
Ballygow Farm, is a mixed use, farm located near Fethard on sea, Co. Wexford. It is a small stream draining approximately a 1km2 agricultural and forested catchment (Fig. 4). It drains into Sandeel Bay 1.5 km downstream.
The plan for NSB features
Diverter-swale-bund
A short (<230 m) 0.5 m wide and 10-20 cm deep swale upstream (see MAP – yellow arrow and top figure 6) was excavated. A structure (e.g., stream-top woody diverter) was located to ensure that enough flood water is drawn from the stream into the swale (MAP – red X).
The flood water flows parallel to the stream along a paleochannel depression on the floodplain. This decreases flow re-entry upstream of the bund (MAP – orange line and bottom Figure 6), the breached levee that currently runs on the left bank was repaired (MAP – yellow line). At the corner of the field, the flood water is retained behind the bund (temporarily) and slowly released back into the stream through a pipe in the bund at 30 cm height with a gradient to ensure water release (bottom of Figure 6). The new bund (MAP – orange line) is 1 m at its highest point and taper to both ends with a total length of 70 m. Soil was sourced from the floor of the bund and a residual soil mound close to the Farmhouse.
Before: construction of features in June 2020.
After: the same features recorded May 2023.
Construction of Bund
June 2020
After: the same features
recorded May 2023.
Construction of Bund
June 2020
After: the same features
recorded May 2023.
Construction of Bund
June 2020
After: the same features
recorded May 2023.
Monitoring Equipment
The monitoring program will demonstrate the efficacy of the NSB features. The following details the location and purpose of each of the Water level sensors (WLS), the rain gauge and the cameras:
Water level sensors (for location see Figs. 5)
- Located upstream (~10 m) of the NWRM network and intake ditch from the stream. This will inform on the upstream hydrograph for summer, winter, high and low flows.
- Located downflow of the “draw-off” structure from the main channel. We propose to install a leaky dam to divert water into the field. The water volume diverted can be quantified.
- Located on the bund floor. This will quantify the storage capacity and time for the return of stored water to the main channel/throughflow.
- Located downstream (~10 m) of the bund outlet pipe. This will quantify the flow volume and duration of the main channel and the offline stored water.
Rain Gauge:
One rain gauge (tipping gauge) will be installed to understand the “input” of precipitation and its impact on the stream discharge and flood peaks.
Cameras:
Installed February 2023 at ponding atea to record flooding events at 5/10 minute intervals. Aim: to capture flood events as they occur.
Storm Videos
See videos above of storm flooding and impact on NBS features.
The Fixes
See below the of revisions to the features onsite which include:
- Extend bund, re-inforce outlet area in corner of Bund and add additional stone outlet area.
- Remove Leaky Dam feature from within the stream and replace with installation of large tree trunk Logs.
The Results
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