Up unto this point the rivers in the landscape have simply been colourised landscape.
The landscape material uses a shader that I created using the URP shader graph to achieve flat-shading appearance and colour the mesh vertices according to their Y value (elevation).
My terrain shader has a number of elevation bands that it lerps between and I had set everything below Y = 0.5m to be shaded blue.
This weekend I took it upon myself to add more believable looking water to the landscape by adding a large plane as wide and long as the whole terrain, to represent a fixed top water level, positioned slightly higher than the 0.5m elevation threshold. I decided upon 2m elevation because I wanted the possibility of the player being fully emersed below the water level and I don't think any of my valleys go below 0m..
The trick is then to create a shader graph for the water material used on this plane that can give the appearance of movement etc.
Here's how I got on with my first go at a water shader for the URP. I am pretty chuffed with the resulting outcome:
The resulting water effect using my first water shader for URP.
The next video is almost 15 mins and is a run down of my understanding of how the water shader graph works. The shader graph is not my work at all - I take no credit for it. I put it together by following this fantastic tutorial video https://www.youtube.com/watch?v=gRq-IdShxpU.