A friend assures me that winter is the best time to work out how water flows on one’s patch: Snow melt will flow to a sink and freeze, and tramping the bounds, one would feel hard ice underfoot where water accumulates.

I just did that, and didn’t feel a thing, but then this property is either flat — no sinks except between raised beds — or sloping visibly downward, so the water would just flow away.

So my friend had a good thought anyhow!