Question: On which river is this city that has N'Dolo Airport situated?

Context paragraphs:
Filair: Filair is an airline based in the Democratic Republic of the Congo.  Its operates from N'Dolo Airport, in Kinshasa.  The airline is on the list of air carriers banned in the European Union, as are all airlines regulated by the authorities in the DRC.

Air Kasaï: Air Kasaï is an airline with its head office on the property of N'Dolo Airport in Barumbu, Kinshasa, Democratic Republic of the Congo.  It operates charter services within Africa.  Its main base is N'Dolo Airport, Kinshasa.

Malift Air: Malift Air was an airline based in Kinshasa, Democratic Republic of the Congo.  It operated domestic passenger and cargo services from 1995 until 2009.  Its main base was N'Dolo Airport, Kinshasa.

Business Aviation: Business Aviation (airline) was an airline based in Kinshasa in the Democratic Republic of the Congo.  It was established in 1998 and operated scheduled domestic and international services, as well as charter flights and wet-lease services.  Its main base was N'Dolo Airport, Kinshasa.  In 2007, the airline was shut down.

Kinshasa: Kinshasa ( ; ] ; formerly Léopoldville (French: "Léopoldville" or Dutch    )) is the capital and the largest city of the Democratic Republic of the Congo.  It is situated on the Congo River.

1996 Air Africa crash: The 1996 Air Africa crash occurred on 8 January when an overloaded Air Africa Antonov An-32B aircraft, wet leased from Moscow Airways and bound for Kahemba Airport, overshot the runway at N'Dolo Airport in Kinshasa, Democratic Republic of the Congo after failing to take off and ploughed into Kinshasa's Simbazikita street market.  Though four of the aircraft's six crew survived, 225 fatalities and around 253 serious injuries occurred on the ground.  This is the largest number of non-passenger ground fatalities caused by the accidental crash of an aircraft.

N'Dolo Airport: N'Dolo Airport (IATA: NLO, ICAO: FZAB) , also known as Ndolo Airport, is a secondary airport in the city of Kinshasa, Democratic Republic of the Congo, located in the commune of Barumbu near the city center.

Free Airlines: Free Airlines is an air operator out of N'Dolo Airport, Kinshasa, Democratic Republic of Congo.

Air Tropiques: Air Tropiques is an airline based in Kinshasa, Democratic Republic of the Congo.  It operates domestic, regional and charter flights.  Its main base is N'Dolo Airport, Kinshasa.

Dolo Airport: Dolo Airport is an airport serving Dolo in Ethiopia.

Supporting paragraphs: N'Dolo Airport Kinshasa
Answer: Congo River