Of or pertaining to rivers or their surrounding environments.
Some fourteen years later the company obtained from Congress authority to reclaim a large area of riverain land on which to construct its terminus and yard, but it was not until July, 1912, that trains ran into its present Buenos Aires terminus, Retiro Station.1943 September and October, “Notes and News: B.A.P.R. Diamond Jubilee”, in Railway Magazine, page 307:
riverain
noun
Etymology Borrowed from French riverain.
1
A person who lives beside a river.
But, in the eyes of the riverains, the coup threatened not just Bashir—the North's historical domination of power and wealth in Sudan stood in the balance.2016, Philip Roessler, Ethnic Politics and State Power in Africa, page 169: