This is the brook between the building plots B38 and B39 where the construction of a dam is planned.
First, the “temporary water outlet” is set. This is a concrete block with an opening in the middle, in which a pipe with a diameter of 20 centimeters is inserted. We are going to build it at home and take to the brook where it is going to be anchored slightly above the flowing water.
Two pipes with a total length of ten meters and a diameter of 20 centimeters are then connected to the “temporary water outlet”. The water will flow through this device during the construction of the dam. When the dam is finished, the outlet will be closed, so that the water rises behind the dam.
The brook bed is filled with soil and stones, while the water flows through the “temporary water outlet”. The best time to build a dam is the dry season from the beginning of January to the end of April, because otherwise a much bigger pipe would be needed or the construction would not be possible because of too much water.
Then, the filling will be compacted and a concrete slab with a length of ten meters, a width of three meters and a height of 30 centimeters is cast.
Outer walls are cast onto the concrete slab at a height of one meter. The width of the walls corresponds to the width of the dam. A cross-section for the water flow of ten meters width and one mete height (10 m²) appears to be large, but the bigger it is, the lower is the risk of undercutting in the event of heavy rainfall.
The spaces left and right to the concrete walls are being filled with soil and stones.
A bridge is being built. It must be strong enough that the backhoe with a deadweight of nine tons and a load of three tons can pass safely.
To make sure that fish can be farmed behind the dam, a lattice (yellow) has to be fixed. In this context it is understandable that the cross-section for the water flow of 10 m² is not too big. Thus, the danger of the lattice clogging is considerably reduced.
In the last step, the temporary water outlet is closed (red) so that the water accumulates behind the dam and finally runs over the concrete structure.