This is an example of how the vector counters from yesterday could be used in a more complex way, to suggest movement of water across a landscape. Here it's a battlefield for a possible wargaming scenario, but it could make a roleplaying encounter too.
The main feature on the map is a dry riverbed, taking up about half. For the purposes of the scenario it's assumed to be flooding; the counters show the direction and strength of the flow. I've marked them with ranges, from D3 to D6+1, the randomness representing eddies, debris and so on. The D3 is for the shallows and the D6+1 the deepest channel.
In game, units which end a move within a certain distance of a counter are carried by the force of the water in the direction shown on the closest counter, and the given distance. Here I'm assuming a table of about four feet by four feet and measurement in inches.
The rectangular area is the deployment zone for the retreating units, and their aim is to escape across the flood and off the right-hand edge. The pursuers enter from the left, maybe with a delay, especially if the force is more mobile overall. For a simple measure of success compare the units which escape against those which don't. Any carried off the top edge are lost, maybe into the clutches of the pursuers, or over a pulp waterfall.
The arrangement of elements should make a challenge for both players and it should have good replay value. How much of a holding force? How far upstream to cross?
If you want to add to it, maybe assume the riverbed begins empty, with a shallow slope on the left, a steep on the right, and increase the strength of the flow gradually over time.
That shows the strength of the counters, the easy variability. Not only do you not need river terrain to play over a river, you don't ever have to play over the same river. Winds can rush over open spaces, maybe even tornadoes, black holes can pull in spacecraft, vast electromagnets can charge up to repel walkers, and magical forces wax and wane.
Well, actually that shows the fun of gaming - imagination, maybe a few useful objects._