This is not really a Fun FAct of the Day, but more of a Quiz:


I received one of my Alumni magazines, I won’t mention the University but I will say it’s across the Alabama line, the colors are Orange and Blue and they say “War Eagle’, and in the magazine, it has a take on the TV Show “Are You Smarter than a 5th Grader”.  The title of the section in the magazine is “Are you smarter than a freshman?”.  One of the questions was:


You are working for a humanitarian organization in a tropical, developing-world country.  Your task is to help a community develop a water storage structure to take advantage of seasonal rains through rainwater harvesting for storage and subsequent use in food production.

How will you estimate the flow rate of the small stream that will supply water to the planned storage reservoir?  You do not have any tools other than your watch, the ubiquitous machete and the natural resources around you.



First, select a section of flowing stream that is fairly uniform in depth and width.  Then, use your machete to cut some sticks and/or vines to use for measuring distances and depths.  Estimate the length of the sticks or the vines.  For the vines, you will need to tie a stone on one end.

Now, estimate both the depth and width of the water using sticks and vines.  Use these measurements to calculate the cross-sectional area of the flowing stream.

Once you have an estimate of the cross-sectional area, drop one or two floatable fruits such as orange or grapefruit into an upstream station ‘A’ of known distance to a downstream station ‘B’ (you can measure the distance with your vines or sticks). Using your watch (or by counting by 1000, 1001, 1002, etc.) determine the time it takes the float to travel downstream over the known distance between points A and B.  Then, calculate the velocity using the travel time and distance between points A and B.

Multiply the velocity by the previously determined average cross-sectional area in the general flow equation Q = V x A to determine the flow rate of the stream.

Now you know the approximate flow rate of water in the stream (at least at this point in time).  You can use this flow rate to help you plan for projected uses and ultimately the optimum size of the storage structure.