Rivers falling into the Arabian Sea: The Narmada and the Tapti rise near the eastern extremity of the Satpura hills, flow westward and fall into the Gulf of Cambay. These rivers do not form any deltas because the tides wash away all the alluvium that the rivers bring. During flood, these rivers are navigable. Their chief use is that railways have been built in their valleys. Rivers falling into the Bay of Bengal: The Mahanadi rises in the hills of Madhya Pradesh, while the Godavari, the Krishna and the Cauvery rise in the Western Ghats and flowing eastward fall into the Bay of Bengal. All these rivers are broken by rapids and hence are not useful for navigation. The deltas of these rivers are very fertile and are irrigated by the canals taken from these rivers.