It is hard to know why your Sycamore tree died without more information.  A tree that was well planted and healthy for 5 years should be able to withstand the portion of xeric turf pictured here.  Did the tree die suddenly or did it deteriorate over a few years?  Is there  any damage around the base of the tree from lawn care equipment? Is there any visible disease or insect damage? Are there girdling roots around the base of the tree?  How much water did the tree get during the winter? How much water does the "green" side get?  A tree that is drought stressed can be severely affected by wide temperature swings such as we had in early September 2020 or bitter cold such as we had in mid February this year. 

It is most likely that your tree died from a variety of stressors, and that your new watering practice was a contributing factor but not the only cause.