This word is acceptable for play in the US & UK dictionaries that are being used in the following games:

• Lexulous
• Wordscraper
• Wordosaur

adj. Relating to or resembling a river.

adj. Located on or inhabiting the banks of a river; riparian: "Members of a riverine tribe ... were wading in the swamp, whose water they had impounded in a series of dams” ( Alex Shoumatoff).

adj. Operating on or equipped to operate on rivers: riverine units of the Marine Corps.

adj. Of or pertaining to rivers, or located on or by a river

Of or pertaining to a river; resembling a river in any way.

"He served in Korea as an Air Force intelligence analyst and later served in a riverine unit in Vietnam."

fluvial   

counterguerrilla    andoppressive    self/other    high-impedance    counterinsurgency