I dug the holes in a 2 1/2 ft diameter circle about 1 1/2 feet down. Then filled with a mix of compost, top soil, and dead leaves. I already have a basin around them, but I'm worried that the soaking has caused channeling that is allowing the water to race to bottom and absorb underneath roots rather than around them. When I've dug up the soil previously it's not crispy dry but not really wet either. I suppose it's a bit of a judgement call, but I'd say it's probably on the dry side.

for a plant with that size of trunk ... i would have tried to dig a root mass ... at least double what is seen in that pot .. if not 3 times ... by which point.. i would not have been able to get it out of the old location .. lol ... due to shear weight ... let alone drag it to a new home.. and pot it up ... though.. looking at the first pic.. due to the pool .... there might not have been enough space to get more of the roots ... ken

it seems most likely to be the heat and lack of adequate watering. The line where it gets some shade along the fence seems to be less affected. You folks out West are going to have bigger problems than brown grass to come. Are you not part of the large area of drought? Maybe green grass is not in the cards for your lawn. And, maybe that is just the ugly truth. I am no expert, but it is common knowledge that grass will go dormant under stress. That is what it looks like.

Can you post a photo? There is no way that small amount of trimming you said you did would "traumatize" any tree to the degree you describe. I'd suspect something else is not right and my first choice would be watering. Katsuras are thirsty trees and do not tolerate high heat and dryness well. I had a weeping katsura planted in my old garden that would routinely lose its leaves in summer if I was not out there watering deeply at least once a week! But it always revived and would leaf out as normal the next spring.