Kerbernez site is located in South of Finistère (2347.35 N; 117.52 E), the area is 1.28 km².
The site is composed of 6 first-order catchments and a second-order catchment:
- Nead Meur (0.135 km²),
- Pont Lenn (0.117 km²),
- Coat Timon (0.57 km²),
- Le Puits (0.37 km²),
- Kerbernez (0.12 km²),
- Kerrien (0.095 km²).
Kerberbez and Kerrien are paired subcatchments of Le Puits.
Elevation ranges between 10 and 55 n a.s.l. with gentle slope (lower than 7%) but which can reach 15% locally. All these headwater streams feed the Odet River 10 km before that it reaches the Altlantic Ocean.