I see triangles
To find fish on a rainfed river, Andrew Ralph looks for shapes in the surface
A simple way to read a river, suggested by Andrew Ralph
IT STARTED FOR ME A FEW YEARS ago when North Country guide Stuart Minnikin and I were fishing on Lancashire’s River Calder, near Burnley. We were chatting about technique and landed on the subjects of rivercraft, water types within a pool, and fish location. Stuart then mentioned something that has stuck with me ever since. He said: “It’s all about triangles.” What a revelation: Stuart’s triangles have helped me to read rivers and understand where trout lie and feed. Where are these triangles? You’ll find them in the fast-flowing parts of a rainfed river, areas of significant water volume and velocity, particularly at the pool head. Here the surface disturbance has a triangular appearance when viewed from the riverbank.
HOW A RAINFED RIVER FLOWS
There’s no need to understand the complex science of moving water but I think all anglers would benefit from some basic knowledge. On rainfed rivers, pools are, in the main, made of shallow water falling into a deep section and then lifting at the tail. This is repeated over and over, creating a distinctive run-and-pool sequence caused by water moving at pace over rock and gravel. Water moves in layers at different speeds: it’s fastest at the surface, slowest at the bottom. Water flowing down a river also has a fastest point, normally in the centre, but it can be to one side where bends, shallows, rocks or islands have an effect. So we have a fastest point, a main chute of flow, which starts to slow as it nears both banks – hence a natural triangle is formed. Fluid resistance is caused when water passing at pace through, over or around rock and gravel meets the surface, perhaps at a visible boulder, the bank, an unseen riverbed obstruction, or it could be a marginal shallow area. This contact causes friction and slows the flow. The continual flow and displacement of water is called turbulence by anglers. Another key point is that, the faster the flow, the greater the friction and the more pronounced and visible the turbulent area. It’s worth remembering that the river is a living thing, always changing, and with only an extra inch of water, a well-known pool can look completely different.
“We have a fastest point … which starts to slow as it nears both banks”