Peter Coleman-Smith reports:
The walk took place this morning in the pouring rain and despite that it was great fun.
Yesterday pm the Met Office issued a Yellow warning for lightning this morning. I checked at 9am and the nearest lightning strikes were in the Netherlands. So, having let attendees know the risks we went ahead. At the end back at the car park I asked for feedback and everyone said they had really enjoyed it and learned a lot.
The very wet conditions undoubtedly affected turnout. Eleven of us set out and spent an hour and a half walking the river from Coombe Dingle up to where the Trym heads off to Cherry Orchards, from there along the Hazel Brook to the ponds in Blaise Castle Estate and back to Coombe Dingle.
We started by looking at some creatures I netted just before we met up. It wasn’t a great Riverfly sample. I hadn’t actually done a full 3 minutes sampling and the river was a bit high (the bugs had wisely buried themselves in the gravel). Even so I was able to point out a few freshwater shrimps (Gammarus pulex) and olive (Baetis sp) nymphs, plus 7 bullheads (Cottus gobio) of various sizes.
As we walked we talked about pollution, the good work by Wessex Water (in response to our reporting of overtopping manholes), problematic weirs, ‘flashy flow regimes’, natural river channels, the role of elephants and beavers, plus the birds/fish/otters being seen along the river. Lots of questions were raised by attendees about what local volunteers are doing (including river cleaning, balsam pulling and reporting pollution). I ended by handing out information on what a healthy river looks like, issues facing our rivers and what’s being done about them – plus what steps any of us can do to help.
I was going to take some photos – attendees said they were happy for me to – but it was so wet I didn’t take any as I didn’t want to wreck my phone.
A highlight of the walk occurred when, having explained that having so many car parks, roads and roofs in the catchment means the Trym can see flash flooding after heavy rain, we actually saw and heard this happen in front of us! It rose more than 15 cm in under a minute, changed colour (and smell) and the noise shifted like someone was twiddling a knob on a radio. Very impressive, the power of moving water. Respect is always needed.
Big thanks to everyone who came along. Do look out for other Bristol Festival of Nature events across the city over the next fortnight.