As a general rule, twice as much water passes through the Pohono Gaging station as the Happy Isles station. Well maybe not a rule but a policy or a guideline. For example the Happy Isles station recorded just over 1300 cfs early this morning, and at Pohono the flow was a bit more than 2800 cfs. So between Happy Isles and Pohono Bridge the flow increased by about 1500 cfs. This additional water came primarily from Tenaya Creek, Yosemite Creek (Yosemite Falls), Sentinel Cr., Ribbon Cr., Bridalveil Cr.,and a few other minor streams. The Majority of this came from Tenaya, Yosemite, and Bridalveil Creeks. Since Yosemite and Bridalveil are downstream from Sentinel Bridge The flow would be Happy Isles plus Tenaya Cr. plus just a little more for water running off the fen at Happy Isles, Royal Arch Cascade, Staircase Falls, and Indian Creek.
Here's an educated guess of the streamflow at Sentinel Bridge.
Happy Isles 1300 cfs
Happy Isles Fen 50 cfs
Tenaya Cr. 600 cfs
Royal Arch Cascade 50 cfs
Staircase Falls 50 cfs
Indian Creek 70 cfs
Total at Sentinel Bridge 2120 cfs