Dronne

The Dronne at the rapids of Saut du Chalard at Champs -Romain

The Dronne, Occitan Drona, is a river in south-west France, which runs in the Limousin, Poitou -Charentes and Aquitaine. It rises in the Périgord -Limousin Regional Natural Park, in the municipality of Bussière -Galant, drained generally in a southwesterly direction and opens after 201 kilometers in the municipality of Coutras as a right tributary to the Isle. On their way the Dronne crosses the Haute- Vienne, Dordogne, Charente, Charente -Maritime and Gironde.

Places on the river

• Bussière -Galant
• Saint- Pardoux- la -Rivière
• Champagnac -de -Belair
• Brantome
• Bourdeilles
• Lisle
• Tocane -Saint -Apre
• Riberac
• Saint- Aulaye
• La Roche -Chalais
• Aubeterre -sur -Dronne
• Saint- Aigulin
• Les Églisottes -et- Chalaures
• Les Peintures
• Coutras

Hydrology

Their average slope is 2.50 m / km. The following figure shows the annual distribution of the average monthly discharge Q in m3 / s, measured at Coutras (mean 38 years):

The annual average value of the Dronne, is located at 25.3 m3 / s The Dronne is strongly influenced by the seasons. In winter ( December to April), the monthly runoff is 34 to 51.9 m3 / s. Having peaks in January and especially in February In summer from July to September the drain goes sharply up to 4.83 m3 / s in August.

Geology

The Dronne rises in the Variscan basement of the Massif Central, its source lies in the extreme south of the granite massif of Nexon -Les Cars. It flows in a southerly direction only briefly by the paragneiss of the Upper Gneiss ceiling, then makes a turn towards the west southwest and passes through the rocks of the Lower Gneiss ceiling ( paragneiss and eyes gneisses ). Then strikes the mica mica slate of Parautochthonen unit, the structurally lowest unit in the Massif Central. After another change of direction after south-southwest and southwest it passes through a narrow valley and relatively notched with rapids to Saint- Saud- leucogranite and then the paragneiss of the Dronne group. Just above from Saint -Pardoux- la -Rivière she leaves the basement in direction southsouthwest, her valley widens and flows from now until its confluence with the flat-lying, Mesozoic sedimentary rocks of the Aquitaine basin ( Jurassic, Cretaceous and Paleogene ). Shortly before Brantome meets the Dronne on the Turonian and Coniacian more resistant, the valley narrows again and in numerous girt by steep walls loops, the river winds to the southwest. In Lisle Dronne met then the softer formations of Santoniums and Campanian, going through them in a wide Talniederung west tions Aubeterre. To the south of Chalais done a final turn towards the West with the Eocene and Oligocene sands as the last obstacle.

Alluvial terraces show that the river has lowered its course since the Lower Pleistocene by up to 100 meters. In the broad valleys even a former meander is received - hence, the river took him to the available free space to complete. The flow constriction behind Brantome he followed, however, since the beginning of the Pleistocene. In the steep walls here different stages can be seen in the reduction of the flow beautifully as a scour.

Ecology

The Dronnetal has very diverse habitats with a very rich flora and fauna. For this reason, 80 % of the river either Natura 2000 protected areas or Special Areas of Conservation.

The following Natura 2000 protected areas are designated:

• From the source to Saint- Pardoux- la -Rivière. The Dronne crosses in this section heathlands, wet meadows, fields and forests.

Several endangered species are found here: freshwater pearl mussel ( Margaritifera margaritifera ), yellow-bellied toad (Bombina variegata ), Helmet Azure Damselfly ( Coenagrion mercuriale ), Marsh Fritillary ( Euphydryas aurinia ), clawed crayfish ( Austropotamobius pallipes ), and several mammals such as the otter (Lutra lutra ) and three species of bats. Among the fish, the bullhead ( Cottus gobio ) and the brook lamprey ( Lampetra planeri ).

• To the south of Brantome to the mouth. At 110 km the Dronne here flows through water meadows, farmland and Bocage. This area is particularly important for the propagation of the sea lamprey ( Petromyzon marinus ). It houses five other endangered fish species, the white clawed crayfish and the European mink (Mustela lutreola ).
• The right-side slopes on the municipalities to Bourdeilles, Grand Brassac and Montagrier. They consist of prairie and heathland, an ideal location for many species of orchids and the Commons juniper (Juniperus communis).

Furthermore, there are another seven Special Areas of Conservation, which largely overlap with the protected areas listed above, including:

• A 25 km long and 541 hectares of comprehensive river section between Mialet and Saint- Pardoux- la -Rivière. Switch to wooded ravines Mediterranean and Atlantic flora depending on the location from each other.
• A 4 km long section of the river at Saint-Front- la -Rivière. Wetland flora and a very interesting, adapted to the limestone walls surrounding flora.
• Between Brantome and Lisle. At 18 kilometers durchschlängelt Dronne woodlands and wet meadows. Your running is bordered by limestone cliffs, but their south sides a Mediterranean flora, the northern sides have a mountain flora.

Photo Gallery

Bridge at Bourdeilles with lock

Mill Moulin du Pont in Montagrier

The Dronne at Coutras

The Dronne at Aubeterre -sur -Dronne

• Platel, J.-P., Célérier, G., Duchadeau - Kervazo, C., Chigot, D. and Charnet, F. ( 1989). Géologique Carte de la France A 1 / 50,000. Feuille Périgueux ( Ouest ). Éditions du BRGM.