Nagao Bridge Live Cam

Geographical and Geological Setting

The Nagao Bridge spans the clear, cascading waters of the Oguni River (小国川), coursing through the Nagasawa district of Funagata Town in Yamagata Prefecture. Nestled at approximately 200 meters above sea level, this section of the valley is defined by gently sloping terraces on either bank, the remnants of fluvial deposition over millennia. The Oguni River here has incised a shallow gorge into Pleistocene gravel terraces, with steep alluvial fans spreading into broader plains as the river descends toward its confluence with the Mogami River. Underlying bedrock in the immediate vicinity comprises late Miocene to early Pliocene sedimentary deposits—chiefly shale, sandstone, and conglomerate—tilted slightly to the northwest. Seasonal snowmelt from the surrounding peaks feeds the Oguni, giving rise to a variable flow regime: peak discharges in April and May, and low flows in late summer and midwinter when portions of the channel form ice cover.