Nera (Danube) basin and it is not navigable. After the filling of the artificial Lake Đerdap, as a result of the Iron Gate I Hydroelectric Power Station which was finished in 1972, the mouth of the river into the Danube was flooded. In order to allow the optimal electricity production, the water level of the Nera at the mouth should not go below , while it must not exceed it if the flooding of the banks is to be avoided. Since the mid-1990s, there are significant problems in fixing the river's level, as the process is costly and complicated. In 2018, representatives
Koshi River north, the Gandaki in the west and the Mahananda in the east. The river is joined by major tributaries in the Mahabharat Range approximately north of the Indo-Nepal border. Below the Siwaliks, the river has built up a megafan some in extent, breaking into more than twelve distinct channels, all with shifting courses due to flooding. Kamalā, Bāgmati (Kareh) and Budhi Gandak are major tributaries of Koshi in India, besides minor tributaries such as Bhutahi Balān. Its unstable nature has been attributed to the heavy silt it carries during the monsoon season and flooding in India has extreme effects. Fishing