San Carlos River (Costa Rica)

The San Carlos River catchment is located in northeastern Costa Rica draining into the San Juan River at the Nicaraguan border. The complex catchment system has an area of 2,370 km² at the downstream gauging station Boca Tapada close to the confluence. The system drains from the Central Volcanic Cordillera at the continental divide at a maximum elevation of 2,326 m.a.s.l. (Platanar volcano) down into the Caribbean plains at around 30m.a.s.l. The two active volcanoes Arenal and Platanar exert a geothermal influence on surface and groundwater with a young geology dating back to the Pleistocene and Holocene. Further away from the active volcanoes, the age of the rocks increases up to 5-9 Mio years (tertiary). The lowlands are dominated by relatively recent fluvial deposits but eroded volcanic remnants along major fault lines can still be detected in the field. The climate is characterized by a Caribbean influence of the northeastern trade winds bringing constantly moist air and precipitation to the whole area. Mean annual catchment precipitation (MAP) with around 4,000 mm is high and the spatial variability from 3,000 to 5,500 mm of rainfall per year is caused by the varied topography. Closer to the continental divide the Pacific climate domain with a marked dry season from December to April exerts a stronger influence. Streamflow regimes reflect the climatic seasonality. Air temperature closely follows the environmental lapse rate with on average 26°C in the lowlands and below 20°C at elevations above 1,000 m.a.s.l.

Country:  Costa Rica
State/Region: Alajuela
Major Population Centers (people in 2017): —

River Length: 142 km
Watershed Area: 2,730 km2
Köppen Climate Classification: —

Source: Confluence of the Jabillos River and Peje River
Mean annual precipitation: —

Mouth: San Juan river
Mean annual precipitation: —
Mean annual discharge at mouth: —