Water runs from the spring down to the river. Water takes only the steepest way down: from each square it runs to its lowest neighbour alone, and splits only when two or more tie for lowest. A lower square that isn't the lowest stays dry. In a hollow it pools, rising until it spills over the lowest point of the rim. A pool floods every square it touches whose ground is at or below its surface.
Drag soil from a square onto a neighbour, or tap a square and then the neighbour. Each shove moves one unit of soil, so digging a channel raises a bank beside it. The number on a square is its height, from 0 to 6.
Fields, houses and the spring can't be dug or built on. Undo takes a shove back; the shove still counts.
Par is the fewest shoves that solve the day, found by a search. On the odd day the search gives up and par is how many shoves scrambled the hillside, so you may beat it.