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658 bytes added, 09:48, 4 December 2017
Measuring the flow of the water energy source
The hydrological data may be essential for the design of the proposed small hydroelectric plant. A lack of flow, and thus shortage of water, will lead to disillusionment when the installation is working due to the large gap between the expected power output and true available power. There is no need to seek accurate hydrological data if the power output of the proposed installation is well below the maximum power usage of the site chosen for the project. Given that the turbine is to be placed near the river, it is highly desirable to know the variations of water level to avoid seeing water invading the facilities during floods.
====Measuring the flow of the water energy sourcerate and head for a stream====Depending on whether The slope of the stream runs horizontalchannel, or whether it comes from a hillis nearly horizontal or very steep, more determines the available "head" is available, which means that we can use different types of water wheels or hydroelectric turbines. Head is the difference in elevation between the point where you start capturing the water (beginning of stream or water diversion) and where you start the use it for energy conversion (where the hydroelectric system is set up). Different levels of head require different types of wheels. Systems requiring a high head include: Pelton and Turgo turbine, and backshot and overshot water wheels. Systems that require little head and a high flow are Crossflow turbines and breastshot water wheels. Finally, when there is no head available whatsoever (horizontal stream), a undershot water wheel can be used.<ref>Practical self-sufficiency by Dick and James Strawbridge</ref>
The water flow is the rate at which water is moving through the stream at any given moment. The water flow must be consistent throughout the length of the stream (assuming the river has a input of water). Since a hydropower system uses the force of the water (dependent on its mass) and its potential energy (dependent on its height) to generate power, the flow rate is necessary when calculating the energy output of a hydropower system. In order to asses assess the amount of flow and head available, it is necessairy necessary to measure itthem both. The height elevation can be measured using measuring tap or a height meter. The flow can be measured by building a temporary dam with a pipe. By then filling a container with a known volume of water while measuring the time required for to fill this volume with a stopwatch, we know can determine the flow. For example, if we hold a five gallon bucket directly in the flow of a stream and it takes 4 seconds to fill up, we can determine that the flow is five gallons per four seconds, or 75 gallons per minute.
== Mechanical power ==

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