Dams construction is built to withstand the rate of water into the reservoir, lake or recreation areas. Often dams are also used to provide water to a hydroelectric plants. Most of the dam also has a section called the floodgates to dispose of unwanted water gradually or sustainable.
Figure 36. Weir
Dams and weir is actually a different structure. Weir is a low head dam structure (lowhead dam), which serves to raise the water level, usually found in the river. Increased surface river water will melimpas through peak / mercu weir (overflow). Can be used as a measure of the speed of water flow in the canal / river and could be a driving force in the traditional pengilingan European countries.
In countries with sizeable rivers and torrential flow, a series of dams can be operated to form a water transport system. In Indonesia, the dam can be used for irrigation when eg river water level is lower than the face of the land to be irrigated.
Figure 37. Building a weir on the river basin
Dodger building is the main building is actually built in the water. Dodger building is needed to enable dibelokannya river water into irrigation network by increasing the water level in the river or to widen the bottom of the river such decision on the type of weir filter paddy (rock bottom weir). Building dams is a threshold that is placed transversely above the riverbed so that the water level in the river becomes higher than the original water level.
But if the river water level is high enough, it can be considered free decision-making buildings that can take water in considerable amounts during the time of administration of irrigation water without the need for fixed water level in the river. To extend the life of the weir or what we often call the maintenance, we can perform several actions, among others:
– With the use of the tunnel, made with natural threshold so resistant to scour sediment and minimum water level is still guaranteed.
– By cleaning the building area of all the impurities that can interfere with the flow of water.
– By patching leaky building so as not to cause the canal.
For the operation of the dam required an operator in charge of operating the dam also set the amount of discharge flow channeled towards channeling appropriately, and also in charge of tending the dam and ancillary buildings. Basically setting the weir is setting the tapping door to drain the water gate kesaluran irrigation and dewatering door arrangement on whenever needed draining.