The site is part of the CZO BVET - Observatory for Research in Environment-Experimental Tropical Watersheds (http://bvet.obs-mip.fr), funded by the French Research Institute for the Development (IRD) and the INSU. The monitoring of the site is operated by personnels from the Yaoundé University and the CRH/IRGM, Yaoundé, Cameroun. The monitoring strategy is based on the acquisition of time series of climate, hydrology and geochemical data in tropical ecosystems from the Upper Nyong watershed. The integration of complementary spatial scales is privileged: (1) at the local scale, with Small Experimental Watershed (SEW) from 1 km2 devoted to process-based studies; (2) at the regional scale, from 1,000 to 10,000 km2, devoted to the quantification of fluxes of dissolved and particulate matters. A network of nested sub-basins within the Nyong River Basin (18,500 km2) in tropical humid forest mildly impacted by anthropogenic activities on the South Cameroun Plateau. The network is comprised of the Nsimi SEW (0.6 km2), and the sampling/gauging stations of Messam on the Awout River (206 km2), Pont So’o on the So’o River (3000 km2), and Mbalmayo (13,500 km2), Olama (18,500 km2) on the Nyong River.