Power Output
To determine the power that can be produced at your site you need to know the flow and head. Flow (the rate at which the water moves in the stream) is measured in gallons per minute (gpm) or liters per second (lps). You can determine this by channeling water into a pipe and then into a container with a known volume and then noting the time it takes to fill the container. The head, which is the vertical distance the water travels, can be measured either by using a transit or by siting along a level. This can also be done by using a transparent hose and using it as a level or by utilizing a length of pipe filled with water with a pressure gauge attached to the end. Once the head and flow are known the appoximate power output can be calculated with the following formula: Head (feet) X Flow(gpm) / 10 = power output (watts)
(Note: the accuracy of the output calculation depends on the accuracy of your measurements.)