Water & earthworks
The people who worked out where water wants to go on a piece of ground, and then moved enough earth to make it go somewhere useful.
Notes
Water is the first decision on a site and the most expensive one to get wrong, because every later choice — where the trees go, where the stock go, where the buildings go — is downstream of it in the literal sense.
The three records here approach it from different ends. Yeomans read the geometry of a valley and derived a whole plan from a single point on it. Lancaster works at the scale of a lot and a street kerb, and spent as much effort on the municipal code as on the shovel. Singh rebuilt a form of earthen structure that had existed in Rajasthan for centuries, one village at a time, until rivers that had stopped running started again.
What the three share is a preference for slowing water down and spreading it out over moving it away — the same instinct, at three scales and on three continents.