An internal drainage board, or IDB, is a formal group, organization, or authority in charge of preparing for and managing floodwater, generally in areas with a high risk of flooding. The term "internal drainage board" is used primarily to refer to such organizations in Wales and England, though similar groups exist elsewhere, such as "watershed districts" in the United States. In general, such groups are given special authority to conduct preventative and repair work within a given geographic region to ensure that water drains appropriately. Their responsibilities include flood prevention; infrastructure preservation; and when possible, ecological conservation. The main responsibility of an IDB is to take all necessary action to ensure proper water drainage from a given area and to prevent flooding, thereby protecting people and property from potentially dangerous floodwater.
There is a wide range of tasks involving routine maintenance and emergency response that an internal drainage board may address in order to guarantee proper water drainage and to prevent flooding. Water sources such as rivers and streams are quite important, as water levels can rise substantially with increased precipitation. An IDB may be called upon to maintain the integrity of such bodies of water, which include rivers, lakes, smaller streams, and others that could flood with increased precipitation. Maintenance of areas that are normally dry but which flood easily with high levels of rain are also very important, as the floodwater must generally flow to a certain place or in a certain direction to avoid damaging anything important.
In some cases, an internal drainage board might be called upon to protect specific important infrastructure components from floodwater. They may, for instance, need to ensure that a certain road, factory, or power station remains safe from floodwater. In some cases, this only involves advising those who are constructing such structures. In others, the IDB may need to take direct action to guarantee that floodwater drains in such a way as to not damage these infrastructure components.
At the most basic level, the primary job of an internal drainage board is controlling water levels within a given geographic area. On a day-to-day basis, this might involve modifying existing waterways, making new waterways, or otherwise modifying an area to better handle floodwater. These boards also commonly manipulate the distribution of plants, as some can help to maintain waterways or to improve floodwater handling. In emergencies, internal drainage boards can coordinate with emergency agencies to divert water from high-risk areas. They may also take charge of efforts to clear and repair an area after a flood situation.