Explanation of Flow Rate Rate: ​ Rate problems are any measured amount over another variable (a ratio). An example would be distance over time like miles per hour. It could be unit price of an item or a production rate. Rate problems are very common in all standardized math tests. Examples: $3 Unit Rate­ $3 per gallon is 1 gallon 80 miles 60 minutes 80 miles in 90 minutes is 90 minutes x 1 hour =53.3mph Flow rate is an amount of fluid traveling over time. It is a key concept when working with any fluids from medical to hydraulics. Here we are primarily looking at water flow rates. Flow rate is the amount of water (volume) over time. The amount of water moving through the system can be measured in one of three different units. They are gpm (gallons per minute), mgd (millions of gallons per day), and cfs (cubic feet per second). Example: Convert cfs to gallons per minute: 90 cf 7.5 gallons 60 seconds 90 cubic feet per second is sec x 1 cf X 1 minute =40,500 gallons per minute Instructional video on how to calculate flow rate The conversions are listed below. 7.5 gallons = 1 cubic foot 5280 feet = 1 mile 640 acres = 1 square mile 43560 square feet = 1 acre mgd x 700 = gpm cfs x 449 = gpm Example: A pipeline has a carrying capacity of 3 cfs. How many gpm can it handle? 3 cubic ft. 7.5 gallons 60 seconds 1350 gallons Solution: 1 second x 1 cubic foot x 1 minute = : minute Example: If the dimensions of California are approximately 220 miles wide and 740 miles long, what is the surface area in square miles of our state? Solution: SA = 220 miles x 740 miles = 162,800 square miles Example: If we had a state average annual rainfall of 30 inches, how many acre feet of water would that be? 640 acres 1 ft. Solution: 162,800 sq. miles x 1sq mi. x 30in x : 12 inches = approx 260 million acre feet Example: How much water is that per person per year if there are 40 million people in California? Solution: 260 million acre feet / 40 million people = approx 6.5 acre feet/ person Example: Approximately, how much water is that per person per day in gallons? 6.5 acre feet 43560 cu. ft 7.5 gallons 1 year Solution: person x 1 acre x 1 cu. ft. x 365 days = approx 5800 gallons per person per day That is a lot of water, where does it all go? Read the short article: Water Use in California ​ Using the numbers from above: 1. Calculate approximately how much water the individual uses? 2. How much water does agriculture use? 3. How much goes back into the rivers and streams? .