Speed of a watercourse needs to be known to put mini-power plant on the small village or a camping. It is necessary also for calculation of durability of a ferry, and for definition of degree of safety of a recreation area. Current speed in different places of the same river can be not identical, and this method allows to define it in the concrete place. For the organization of the beach it is necessary to find the section of the river with the slowest current, and for power plant — with the most powerful.
It is required to you
- Stop watch
- Geodetic compasses
- Long rope
- The wooden stakes 1 m high pointed since one end
- Floating subject
Instruction
1. Choose the suitable site of the coast where the watercourse is rectilinear and it is possible to measure a measured piece. Hammer to the earth wooden a stake, and from it by means of geodetic compasses measure distance, equal 50 or 100 m. The measured piece has to be parallel to the coast (current) of the river and is rectilinear. It is the best of all to carry out control of straightforwardness, having pulled the rope fixed on the ends by wooden stakes along the measured line.
2. Tie a horizontal stick to each stake so that it was perpendicular to the measured line and it is directed towards the river. These sticks are called traverses and serve for "aiming" at measurements. Not less than three people have to participate in measurement.
3. Process of measurement of speed happens so. One of participants takes a floating subject and leaves from the beginning of the measured line upstream. The second participant is at a stake which notes the beginning of a measured piece. He observes a watercourse along the vising stick. The third participant is at a final stake, also observing a watercourse along a traverse. The stop watch is at the third participant.
4. The measurement begins with muster, and there begins it the third participant. He shouts: "Gotov!", behind him determination is declared by the second. The first declares start and throws a subject into the river. When the subject coincides with the first traverse, the second participant shouts: "Time!". On this signal the third participant includes a stop watch and switches off it at the time of crossing by a subject of its traverse.
5. Knowing distance between traverses and time of passing of this distance a subject, calculate the average speed of a watercourse on the measured site on a formula v=s/t where v is the speed of a current, s is length of the measured site, t is the spent time. For accuracy take measurements several times and find an arithmetic average value.