The Durolle (formerly Dorole) is a 32-kilometer-long French river in the departments of Loire and Puy-de-Dôme, in the Auvergne-Rhône-Alpes region. A right-bank tributary of the Dore, which it joins downstream of Thiers, it is a sub-tributary of the Loire via the Allier.
The river rises in the Forez mountains, where rainfall is high throughout the year. After flowing past the town of Noirétable, the Durolle plunges into deep canyons (until it exits the Vallée des Rouets and the Vallée des Usines) renowned for their rich natural and industrial heritage. Known since the Middle Ages for its paper mills, the river owes its fame to its motive power, which enabled cutlery factories to sharpen knives. Today the river's industrial past is used as a tourist attraction.
Toponymy The river's name is thought to derive in part from the (presumed) Celtic root dour or dor, meaning "river" in French. The Dore (the river into which the Durolle flows) also takes its name from these "Celtic" roots. However, the authoritative Dictionnaire étymologique des noms de rivières et de montagnes de France by Albert Dauzat, Gaston Deslandes and Charles Rostaing (Paris, Klincksieck, 1978) explains Dore (and Durolle) by a pre-Celtic radical "found in the Douro of Spain, the two Dora of Piedmont, etc." (article DORE). Moreover, Xavier Delamarre's Dictionnaire de la langue gauloise (2nd edition, Paris, Errance, 2003) does not indicate any Celtic term dor or dour meaning river.
The Durolle, formerly "Dorole", means "little Dore". Its nickname, the Goutte noire (black drop), refers to its color in the 19th century when spinning wheels used the river's water, and is borne by a village crossed by the river in the commune of Chabreloche. The river's name is also used by two communes in the region: Celles-sur-Durolle and Saint-Rémy-sur-Durolle, and a place called Durolle in the commune of Noirétable.
It is called Duròla in Occitan, the regional language of Auvergne.
Geography
River course
Just over 32 km long, the Durolle begins its course at an altitude of around 815 m southeast of the Puy de la Chèvre in the commune of Noirétable in the Loire department. It skirts the town of Noirétable without crossing it, then passes through a number of villages overlooking it, before passing through towns such as Chabreloche and La Monnerie-le-Montel, and finally arriving at the largest town it flows through, Thiers, a town with a strong historical link to it, where it also flows into the Dore.
Upstream, the river follows part of the Forez mountains where it rises, until it enters the commune of La Monnerie-le-Montel, where it divides the Forez foothills. From here, until it leaves the Vallée des Usines in the Moutier district of Thiers, the river flows through a deep valley with small banks, where the cliffs and rocks of the Margerides plunge. The rugged, largely wooded terrain gives the river a sinuous course that follows the steep curves of the mountain. From the point where it passes near Moutier Abbey, the Durolle becomes calmer and the very flat terrain divides its bed into two branches, before these join the Dore at different geographical positions.
Hydrology The drainage basin of the river Durolle measures 172 km2. Its modulus, measured near the Saint-Roch bridge in Thiers, halfway between the source and the mouth, is 3 m3/s. Flow varies significantly throughout the year, and from one year to the next. In dry summer months, the river's flow may drop to 0.05 m3/s; but in winter or autumn, it can rise rapidly to 82 m3/s, as was the case during the flood of March 1988. The river's tributaries are generally small streams with low flows. The main ones are, from upstream to downstream, the Membrun stream, the Pigerolles stream, the Prade stream, the Aubusson stream, the Jalonne, the Semaine, the Dauge, the Martignat, the Bouchet, the Ris and the Boucheries stream.
The Membrun dam, in the commune of Thiers, lies on the course of the Durolle. It was impounded on 22 May 1985 to regulate the river's flow, particularly during periods of drought. Since the late 1980s, the dam has become a popular destination for hikers and walkers.
Communes and cantons crossed
In both the Loire and Puy-de-Dôme departments, the Durolle flows through the following seven communes, from upstream to downstream: Noirétable (source), Cervières, Les Salles, Chabreloche, Celles-sur-Durolle, La Monnerie-le-Montel, Thiers (confluence).
In terms of cantons, the Durolle rises in the canton of Boën-sur-Lignon, and flows into the canton of Thiers, all in the arrondissements of Montbrison and Thiers.
Toponyms The Durolle has given its hydronym to the two communes of Celles-sur-Durolle and Saint-Rémy-sur-Durolle, the latter crossed by a tributary of the Durolle, the Ris.
Drainage basin The Durolle crosses the three catchment areas K295, K296, K297, with a total surface area of 1,456 km. The drainage basin is made up of 58.37% "forests and semi-natural environments", 39.63% "agricultural land" and 2.01% "artificial land".
Geology The geological context of the Durolle has resulted in a river divided into two distinct geological territories, separated by a boundary represented by the Moutier abbey, which lies in the middle of the river. The geological history of the Thiernoise region is characterized by the presence of a major north-south trending fault affecting the regional geological basement: it delimits this basement into distinct blocks while serving as a guide to the tectonic collapse of the western block, while the eastern block remains more or less in place. To the west, the collapse of the block allows sedimentary rocks to fill in: this is the Limagne basin, over which the Durolle flows slowly. To the east, the part of the basement that has not collapsed corresponds to the Forez mountains and its foothills, made up of magmatic rocks over which the river flows torrentially.
The oldest outcrops in the upper part of the river are Paleozoic in age, consisting of various granites sometimes overlain by grus and scree. In the lower reaches, the sedimentary fill is Cenozoic in age; this terrain is not visible, as it is covered by a thick mantle of recent alluvium, sandy and clayey, layered in terraces.
Fauna and flora Numerous plant species have been recorded on the banks of the Durolle. Among them, the most common plant species are ferns (with two species: eagle fern and male fern), plant mosses, European ivy, rubus fruticosus, nettles, clematis, ash and euphorbia. Several tree species are also present in the Durolle's major and minor stream bed, including oaks, broom and fir.
The Durolle canyons are home to several species of fauna, divided into several categories. Mammals include otters and European polecat, while birds range from peregrine falcons and yellowhammers to coal tit and western Bonelli's warbler. The trout is another fish species that lives in rivers with abundant currents and cool temperatures, such as the Durolle, where this species is widespread.
Tributaries The Durolle has thirteen referenced tributary sections, including:
la Jalonne (rd), 7.8 km in the commune of Celles-sur-Durolle alone; the Semaine or Fonghas stream (rg), 11.5 km on the three communes of Viscomtat, Noirétable and Celles-sur-Durolle, with four tributaries including one branch; the Dauge (rg), 3.8 km on the commune of Celles-sur-Durolle alone; the Martignat or Ruisseau de l'Allemand, 3.8 km in the commune of Celles-sur-Durolle alone; le Bouchet (rg), 3.6 km in the communes of Celles-sur-Durolle and La Monnerie-le-Montel; les Ris (rd), 5.2 km on the three communes of Palladuc, Saint-Rémy-sur-Durolle and La Monnerie-le-Montel.
So its Strahler number is three.
History
A long history of human occupation
Gateway to the Rhone corridor An early Gallic settlement (the future town of Thiers) was established at the mouth of the Durolle Gorge, not far from the site of the later Moutier Abbey. The name "Thigernum" used by Grégoire de Tours has a Celtic ring to it, reminding us that this topographical appellation dates from before the Gallic War. The first town seems to have been a road station crossed by a Roman road (the via Agrippa) linking the town of Mediolanum Santonum to Lugdunum via Augustonemetum (Saintes to Lyon via Clermont-Ferrand). But this route was not the only one to link the Allier and Loire valleys. Indeed, although the tortuous Durolle valley was difficult to navigate in its lower reaches, footpaths and bridleways followed the riverbed. The fortified town of Thiers fulfilled this role to the full, commanding the entrance to the Durolle Gorge.
Spinning wheels and factories
Middle Ages
The Durolle's hydraulic power was used in Thiers from the Middle Ages onwards to power flour mills, tanners' fulling machines, papermakers' mallets and, with the development of cutlery, smelters' hammers and grinders. In the 17th century, objects produced in the Durolle Gorge were exported to Spain, Italy, Germany, Turkey, and the Indies.
Industrial revolution From the mid-nineteenth century onwards, the cutlery industry was the only one to survive, thanks to the introduction of machines that heralded the advent of large-scale industry. At that time, the cutlery industry was particularly organized. The manpower needed to make a knife was scattered across the Thiers region; there was an extreme division of labor, with workers specializing in a trade, handed down from father to son, in which they acquired great skill. The steel bars received by the companies are first entrusted to the "martinaires", who thin them (so that they can be sharpened) using hammers powered by the river's hydraulic force. The blacksmiths then receive these bars, with which they forge the knife parts. These pieces are then sent to filers, drillers, grinders and polishers, who sharpen and polish the blades on grindstones driven by the Durolle. The manufacturer does the tempering himself, then, after the sealer has delivered the handles, all the parts are finally handed over to the assemblers, who live in the suburbs of Thiers. The organization of production is thus characterized by the widespread distribution of workplaces in the Thiers region, and more particularly in the Durolle canyons.
At the end of the 19th century, foreign competition prompted Thiers industries to modernize. This modernization involved electrification. A new type of factory was created, integrating all cutlery operations. Paper mills that refused to use these modern production techniques were forced to close; by 1860, there were only around twenty of them left.
The early 20th century
At the beginning of the 20th century, there were a growing number of problems concerning the waters of the Durolle. Firstly, the river's summer flow remained very low and irregular, leading to periods of unemployment. The factories that use the river's motive power can't operate without a sufficient flow of water. In winter, the phenomenon is reversed: the Durolle becomes a torrent in flood with considerable force. The towns in the Durolle canyons are among the most vulnerable to flooding in the Puy-de-Dôme département.
So as not to be dependent on the whims of the Durolle, the factories began using electric power in 1903. In 1920, the Durolle provided an average of 1,000 horsepower per day, compared with 1,500 horsepower for electric power.
Sailing boats and descending logs