The river Canche is one of the rivers that flow from the plateau of the southern Boulonnais and Picardy, into the English Channel. The Somme is the largest example. The basin of the Canche extends to 1,274 square kilometres and lies in the southern end of the departement of Pas-de-Calais. Forming an alluvial valley from 1 to 2 kilometers wide, the Canche is a verdant landscape of calm waters, marshes, meadows and small woods. The gentle gradient, averaging 1.5%, gives the river a meandering course.
The river rises at Gouy-en-Ternois and passes Frévent, Hesdin, Montreuil-sur-Mer before leaving the chalk to flow to the coast between Étaples and Le Touquet-Paris-Plage. Its principal tributaries are the Ternoise, the Planquette, the Créquoise, the Bras de Bronne, the Course, the Dordogne (not the Dordogne) and the Huitrepin which all join on its right bank, i.e. to the north of the Canche. The lie of the land means there’s no notable tributary from the south until the Grande Tringue, which flows from marshland into the small, dredged estuary.
The valley of the Canche has been occupied by man since ancient times because of the productive nature of the land. The unhealthy aspect of marshland means much has been done over the centuries to drain the land efficiently, which has brought about the partial destruction of its original character. The principal activities of the village communities occupying the valley and its surrounds have been (and still are) farming, fishing and reed harvesting. The extraction of peat from the marshes of the lower river was known in the 16th century; peat being the principal means of heating and also a multi-purpose fertilizer. The alder tree, which grew well in the local marshy soils, contributed to bind the ground, and of course, it furnishing timber for many purposes. It was realized that forestry also helped in drainage. Further developments in the 18th century saw permanent enclosures with animals being fenced-in, keeping them off the crops, and property boundaries by the planting of hedges and the digging of ditches, contributing to organized and cooperative farming methods. The 18th century also saw the emergence of new perceptions of marshland, long considered as unhealthy places to in which to live. Administrative authorities encouraged action to recover the peat marshes by drainage work and the planting of more trees. The reduction of marshland again allowed for even more areas of cultivation to feed the increasing population. During the 19th century, technical progress (for example, the replacement of windmills by steam engines) led to further improvements in drainage, contributing to the drying-up of the valley downstream as far as Hesdin). It wasn’t until the last quarter of the 20th century that authorities became aware of the importance of the marshes and started trying to preserve them, having earlier contributed to their disappearance. The Canche and its valley have been incorporated into a national natural reserve since 1987. ).
This article is derived from the French Wikipédia.