There's more to it. For most of the year, the daily flow is determined by contract, and the hourly flow is determined by demand. This is why we experience "the tides" every day. From about 11 pm to 10 am, power demand is lower. Starting at 10 am, when the air conditioners start up in Las Vegas and Los Angeles, the flow quickly increases by about 4-5,000 cfs. All the way down the river, you will need to know whether you are on high tide or low tide--especially when you tie your rafts for the night. On some of the most challenging rapids, the tide makes a big difference in how you run them and how difficult they are.
For most of the summer season, the flow will fluctuate between 10,000 and 15,000 cfs (more or less). Then starting on Sept 1, the daily flow is cut, so that you fluctuate between 7,000 and 12,000 cfs. These are daily fluctuations. You will experience this every day. The morning rise tends to come pretty fast.
As you go downstream, you need to calculate when high and low tides will occur at your location. Figure the speed of the water at 5 mph. So if you're at Crystal Rapid, mile 97, your tidal shift is 19.5 hours. That is, the water you are in passed through Glen Canyon Dam 19.5 hours ago. That means that the transition from low tide to high tide starts at about 5:30 am (10:00 yesterday plus 19.5 hours).