Case study — Warwickshire Wildlife Trust
At Riverfly HQ, we always love to hear about examples of how Riverfly data is being used by our hubs. The below case study was sent to us by Warwickshire Wildlife Trust, and it’s a great example of the value of Riverfly surveys in monitoring the outcome of river restoration projects.
Pickford Brook, a small tributary of the River Sherbourne, flows through Coventry's urban landscape before joining the River Sowe, a tributary of the Warwickshire Avon. A 100-meter section of the brook runs through the Jacobean Hotel grounds, where it was previously confined between hard-engineered banks made of gabion baskets and large quarried stones.
While marginal vegetation provided some habitat benefits, the area experiences a “flashy” flow regime, with rapid runoff from urban surfaces and very low flows during dry periods. To prevent the brook running dry, two low weirs had been installed help retain water, however this reduced fish passage and sediment transport. The SVP carried out restoration work on this stretch of the brook, removing the weirs and installing stone berms narrow the channel and increase flow diversity. These changes have improved fish passage along the brook, reduced siltation, and increased oxygen levels, resulting in cleaner gravels that support thriving habitats for invertebrates.
The effectiveness of these measures can be seen in the scores recorded on the riverfly data. Species variety and abundance have been measured to gauge the overall health of the site. The weirs were removed in May 2024, four months later, by September 2024 the data collected indicated increased species diversity within Pickford Brook, including Caddisfly which were absent in the May 2024 sample. The September sample had a large number of very small cased caddisfly which had never been found in such abundance at the site over the previous 3 years, as well as an increase in Baetidae and Blue Winged Olives (Ephemerellidae) moving the score from 2’s and 3’s previously up to 6 in 3 months.
We are excited to perform the first monitoring of 2025 and hope to see continuing improvement in the site.
Before river restoration – slow flow and silty, with much filamentous algae present:
After – teaspoon for scale on size of numerous cased caddis present in sample 3 months after work:
