I played around by imposing an angled frame with a 4 1/2" square opening and a 5 1/2" exterior over each cloth-woven square ...
basted down the raw edges up to the inner frame dimensions ...
which is easier to see from the back ...
then cut away the excess ...
and started overlapping the pieces so they were effectively 5" to a side ...
After which I played around with different arrangements until I settled on one that represented some of the major features on the floodplain (dry creek bed channels, scoured bedrock, poverty weed patches, etc.) ...
Next up will be the greener, tree-covered part of the property, as depicted in these composite shots ...
(Seriously, I'll use any excuse to include grandkid pictures in my posts)