The hydrographic slopes adjacent to the Flapjack River are:

• north side: Gouin Reservoir, Mattawa Bay, Hanotaux Bay, Plamondon Creek, Saraana Bay;
• east side: Arcand Lake, Bureau Lake (Gouin Reservoir) (South Bay), Oskélanéo River, Tessier Lake (Gouin Reservoir);
• south side: Clova River, Douville River, Tamarac River (Gatineau River);
• west side: Tamarac River (Gatineau River), Provancher Creek, Médora Lake, Mégiscane River, Suzie River, Bignell Creek, Chassaigne Lake.

The Flapjack River originates at the mouth of a Gut Lake (length: 0.8 kilometres (0.50 mi); altitude: 439 metres (1,440 ft)). The mouth of this head lake is located at:

• 5.5 kilometres (3.4 mi) south-west of the village center of Clova, Quebec;
• 2.9 kilometres (1.8 mi) east of the Tamarac River (Gatineau River);
• 28.9 kilometres (18.0 mi) south of the mouth of the Flapjack River (confluence with Mattawa Bay);
• 72.2 kilometres (44.9 mi) south-west of the village center of Obedjiwan, Quebec (located on a peninsula on the north shore of Gouin Reservoir);
• 103 kilometres (64 mi) south-west of the Gouin Dam erected at the mouth of the Gouin Reservoir (confluence with the Saint-Maurice River).^[2]

From the mouth of the head lake, the Flapjack River flows over 39.2 kilometres (24.4 mi) according to the following segments:

• 4.1 kilometres (2.5 mi) north across Elsie Lake (length: 1.2 kilometres (0.75 mi); altitude: 432 metres (1,417 ft)) on its full length, up to at the Canadian National Railway;
• 7.3 kilometres (4.5 mi) to the north crossing the Bull Lake (length: 6.7 kilometres (4.2 mi); altitude: 423 metres (1,388 ft)) on 5.5 kilometres (3.4 mi) to a bridge on a forest road;
• 3.7 kilometres (2.3 mi) to the Northwest, crossing Lake Tozer (length: 2.4 kilometres (1.5 mi); altitude: 422 metres (1,385 ft)) and the southern part Ada Lake (length: 1.9 kilometres (1.2 mi); altitude: 421 metres (1,381 ft)) to the southern limit of Provancher Township;
• 9.9 kilometres (6.2 mi) northeasterly in Provancher Township crossing the northern portion of Ada Lake and Stone Lake (length: 4.8 kilometres (3.0 mi); elevation: 420 metres (1,380 ft)) which is formed by a widening of the river, until the discharge of the "Lake at Foisy" and "Lake à la Pitoune";
• 13.1 kilometres (8.1 mi) north through a segment of 8.0 kilometres (5.0 mi) where the river widens to the southern limit of the township of Poisson;
• 1.1 kilometres (0.68 mi) north in the Township of Poisson to the mouth of the river.^[3]

The mouth of the Flapjack River is located at: South of the mouth of Mattawa Bay;

• 46.9 kilometres (29.1 mi) south-west of the village centre of Obedjiwan which is located on a peninsula on the north shore of Gouin Reservoir;
• 94.8 kilometres (58.9 mi) south-west of Gouin Dam;
• 129 kilometres (80 mi) west of the village centre of Wemotaci (north shore of the Saint-Maurice River);
• 217.7 kilometres (135.3 mi) north-west of downtown La Tuque.^[4]

The mouth of the Flapjack River meets with Mattawa Bay. From there, the current flows over 164.9 kilometres (102.5 mi) until Gouin dam, according to the following segments:

• 53.0 kilometres (32.9 mi) northeasterly, crossing Mattawa Bay, Du Mâle Lake and the western portion of Gouin Reservoir to the height of Obedjiwan Village;
• 81.9 kilometres (50.9 mi) to the East, crossing the Marmette Lake, then to the South-East crossing in particular the Brochu Lake then to the East crossing the Kikendatch Bay until Gouin Dam.

From this dam, the current flows along the Saint-Maurice River to Trois-Rivières.

• Saint-Maurice River
• Gouin Reservoir, a body of water
• Kikendatch Bay, a body of water
• Brochu Lake, a body of water
• Nevers Lake, a body of water
• McSweeney Lake, a body of water
• Marmette Lake, a body of water
• Du Mâle Lake, a body of water
• Mattawa Bay, a body of water
• La Tuque, a city
• List of rivers of Quebec