You should pick up some civil engineering books. I did 1 year before I realized I hated it, but they’re full of lovely equation that are like [Size of sand grains] x [percentage of empty space filled with water] x ([speed of water flow] + 14) x [Bill Factor]
(We add 14 to prevent the formula from breaking down)
(The Bill Factor was created by Bill Johnson and is 3.11 when it’s raining and 1.70 when it’s not. It is based on practical observations and has no theoretical basis)