Ganges Basin (112,490 km²), West Bengal (71,485 km²), Haryana (34,341 km²), Himachal Pradesh (4,317 km²) , Delhi, Arunachal pradesh(1,484 km²), the whole of Bangladesh, Nepal and Bhutan. Several tributaries rise inside Tibet before flowing south through Nepal. The basin has a population of more than 500 million, making it the most populated river basin in the world. The basin comprises semi-arid valleys in the rain shadow north of the Himalaya, densely forested mountains south of the highest ranges, the scrubby Shiwalik foothills and the fertile Gangetic Plains. Central highlands south of the Gangetic Plain have plateaus, hills and mountains intersected by valleys
Nutrient cycling in the Columbia River Basin to dissolved phase compounds. This process can introduce nutrients, most notably phosphorus, into the Columbia watershed. Both chemical and physical weathering occur, usually together, and this coupling tends to accelerate the other. Precipitation varies across the basin, influencing the amount of weathering and subsequent runoff that transports this material into the basin. Organic matter such as leaves may also naturally fall into the waterways through runoff. Over time, this material is respired, releasing assimilated nutrients into the environment. An important source of nutrients, such as nitrogen and phosphorus, for rivers in the Pacific Northwest is the spawning of salmon and