Ternoise

The river Ternoise (Ternaas) is one of the small chalk streams that flow from the plateau of the southern Boulonnais and Picardy, via the Canche, into the English Channel. The basin of the Ternoise extends to 342 km2 and lies in the southern end of the département of Pas-de-Calais. It is one of the rivers of the Seven Valleys tourist area and gives its name to the Ternois area.

Geography
The 41.4 km long river rises at Ligny-Saint-Flochel and passes through Saint-Pol-sur-Ternoise to join the river Canche at Huby-Saint-Leu, near to the town of Hesdin.

Towns and villages along the course
The Ternoise flows through the following places (all within the Pas-de-Calais department):
 * Ligny-Saint-Flochel, Roëllecourt, Saint-Michel-sur-Ternoise, Saint-Pol-sur-Ternoise, Gauchin-Verloingt, Hernicourt, Wavrans-sur-Ternoise, Monchy-Cayeux, Anvin, Teneur, Érin, Tilly-Capelle, Blangy-sur-Ternoise, Blingel, Rollancourt, Auchy-lès-Hesdin, Le Parcq, Grigny and Huby-Saint-Leu.

Tributaries
The Faux and the Eps are the only principal watercourses joining the Ternoise.

Hydrological Information
The Ternoise is a very uniform river. Seasonal flow fluctuations are not very marked, similar to the Canche or the Somme, its neighbours. The higher water flows occur at the end of winter and in the spring. Average flows vary between 3.44 m³ per second in September to 5.36 m³ per second in March.