The river is 1,143 km (710 mi) long and up to 700 m (2,300 ft) wide at its delta;[3] with a total area of 98,740 km2 (38,120 sq mi), the river basin covers more than 67% of West Kalimantan.[2][5] The discharge rate varies through the year, averaging around 6,000–7,000 m3/s (210,000–250,000 cu ft/s) at the delta and 2,000 m3/s (71,000 cu ft/s) upstream, at the confluence of the Tawang River. The discharge peaks during the rainy seasons in April and November, during which the water level may rise by 10–12 m (33–39 ft) overnight, overflowing river banks and flooding the nearby areas.[2][6][7]