Hi Steve

The main point was using geodesic lines and Google Earth as a reference for HASL if you know where one point actually confirms HASL. Colour coding and such aids in what you identify for the landscape, so any depressions indicating water courses leading somewhere cannot be disputed, as you're offering in your observations.

For some folk, being off by even a few centimeters is the basis for their whole disregard for what you are observing, no matter where water courses and ponds actually are, nor where constructions are that will be downhill from a water source. While some folk may point out that a certain point on the landscape is lower than another point by several feet, so could not possibly contribute to water flow, they may overlook shadufs, or choose to overlook such a thing. Same with a simple water wheel and buckets, or the Archimedes Screw.

It all comes down to the importance of water supply and what it was used for: drinking and food preparations, metal work, mortar if such was used...even floating blocks used in construction if that is what is being offered.

All the best to you